What is the Security Tango?The Security Tango is my name for the dance you have to do every time you want to assure yourself that your computer is free of viruses, spyware, keystroke loggers, backdoors, trojans, and other forms of malware (click the Definitions button in the menu to see what all those things mean). It's something you need to do regularly and often - daily is not too often! The simple act of getting on the Internet and downloading email or going to a Web page can expose your computer to malicious crackers who would love to take over your machine for their own use.
To dance the Security Tango, click the Let's Dance link up above.
Two left feet? Don't worry - it's not as hard as you might think!
Which Operating System Do You Use?
Originally, the Security Tango was mostly for Windows-based computers. I'm sure that those of you running Linux or a Macintosh used to laugh yourselves sick at all the machinations that your Windows-using friends had to go through to keep themselves safe. But don't get too complacent - your time is here! As Linux and the Mac have become more popular, we've see more viruses for them. Yes, there are verified malware programs out there for both the Macintosh and for Linux. You need to protect yourself. Equally importantly, if you don't at least run an antivirus program, you run the risk of passing a virus on to your Windows friends (assuming any of them actually talk to you). And that's just not being a good net citizen!
So I've split the Tango into parts - Windows, Linux, the Macintosh, etc. I'll add more as changes in technology warrant. But you get to all of them by that same "Let's Dance!" button in the menu!
Latest Virus Alerts
Microsoft Windows operating systems
According to numerous open-source reports, a widespread ransomware campaign is affecting various organizations with reports of tens of thousands of infections in over 150 countries, including the United States, United Kingdom, Spain, Russia, Taiwan, France, and Japan. The software can run in as many as 27 different languages.
The latest version of this ransomware variant, known as WannaCry, WCry, or Wanna Decryptor, was discovered the morning of May 12, 2017, by an independent security researcher and has spread rapidly over several hours, with initial reports beginning around 4:00 AM EDT, May 12, 2017. Open-source reporting indicates a requested ransom of .1781 bitcoins, roughly $300 U.S.
This Alert is the result of efforts between the Department of Homeland Security (DHS) National Cybersecurity and Communications Integration Center (NCCIC) and the Federal Bureau of Investigation (FBI) to highlight known cyber threats. DHS and the FBI continue to pursue related information of threats to federal, state, and local government systems and as such, further releases of technical information may be forthcoming.
Initial reports indicate the hacker or hacking group behind the WannaCry campaign is gaining access to enterprise servers through the exploitation of a critical Windows SMB vulnerability. Microsoft released a security update for the MS17-010 vulnerability on March 14, 2017. Additionally, Microsoft released patches for Windows XP, Windows 8, and Windows Server 2003 operating systems on May 13, 2017.
According to open sources, one possible infection vector may be through phishing.
Indicators of Compromise (IOC)
See TA17-132A_stix.xml for IOCs developed after further analysis of the WannaCry malware.
Three files were submitted to US-CERT for analysis. All files are confirmed as components of a ransomware campaign identified as "WannaCry", a.k.a "WannaCrypt" or ".wnCry". The first file is a dropper, which contains and runs the ransomware, propagating via the MS17-010/EternalBlue SMBv1.0 exploit. The remaining two files are ransomware components containing encrypted plug-ins responsible for encrypting the victim users files. For a list of IOCs found during analysis, see the STIX file.
Displayed below are YARA signatures that can be used to detect the ransomware:
This artifact (5bef35496fcbdbe841c82f4d1ab8b7c2) is a malicious PE32 executable that has been identified as a WannaCry ransomware dropper. Upon execution, the dropper attempts to connect to the following hard-coded URI:
Displayed below is a sample request observed:
GET / HTTP/1.1
If a connection is established, the dropper will terminate execution. If the connection fails, the dropper will infect the system with ransomware.
When executed, the malware is designed to run as a service with the parameters “-m security”. During runtime, the malware determines the
number of arguments passed during execution. If the arguments passed are less than two, the dropper proceeds to install itself as the
ServiceName = "mssecsvc2.0"
DisplayName = "Microsoft Security Center (2.0) Service"
StartType = SERVICE_AUTO_START
BinaryPathName = "%current directory%5bef35496fcbdbe841c82f4d1ab8b7c2.exe -m security"
Once the malware starts as a service named mssecsvc2.0, the dropper attempts to create and scan a list of IP ranges on the local network
and attempts to connect using UDP ports 137, 138 and TCP ports 139, 445. If a connection to port 445 is successful, it creates an additional
thread to propagate by exploiting the SMBv1 vulnerability documented by Microsoft Security bulliten MS17-010. The malware then extracts &
installs a PE32 binary from it's resource section named "R". This binary has been identified as the ransomware component of WannaCrypt.
The dropper installs this binary into "C:\WINDOWS\tasksche.exe." The dropper executes tasksche.exe with the following command:
When this sample was initially discovered, the domain "iuqerfsodp9ifjaposdfjhgosurijfaewrwergwea[.]com" was not registered, allowing the
malware to run and propagate freely. However within a few days, researchers learned that by registering the domain and allowing the
malware to connect, it's ability to spread was greatly reduced. At this time, all traffic to "iuqerfsodp9ifjaposdfjhgosurijfaewrwergwea.com" is
re-directed to a monitored, non-malicious server, causing the malware to terminate if it is allowed to connect. For this reason, we recommend
that administrators and network security personnel not block traffic to this domain.
Ransomware not only targets home users; businesses can also become infected with ransomware, leading to negative consequences, including
- temporary or permanent loss of sensitive or proprietary information,
- disruption to regular operations,
- financial losses incurred to restore systems and files, and
- potential harm to an organization’s reputation.
Paying the ransom does not guarantee the encrypted files will be released; it only guarantees that the malicious actors receive the victim’s money, and in some cases, their banking information. In addition, decrypting files does not mean the malware infection itself has been removed.
Recommended Steps for Prevention
- Apply the Microsoft patch for the MS17-010 SMB vulnerability dated March 14, 2017.
- Enable strong spam filters to prevent phishing emails from reaching the end users and authenticate in-bound email using technologies like Sender Policy Framework (SPF), Domain Message Authentication Reporting and Conformance (DMARC), and DomainKeys Identified Mail (DKIM) to prevent email spoofing.
- Scan all incoming and outgoing emails to detect threats and filter executable files from reaching the end users.
- Ensure anti-virus and anti-malware solutions are set to automatically conduct regular scans.
- Manage the use of privileged accounts. Implement the principle of least privilege. No users should be assigned administrative access unless absolutely needed. Those with a need for administrator accounts should only use them when necessary.
- Configure access controls including file, directory, and network share permissions with least privilege in mind. If a user only needs to read specific files, they should not have write access to those files, directories, or shares.
- Disable macro scripts from Microsoft Office files transmitted via email. Consider using Office Viewer software to open Microsoft Office files transmitted via email instead of full Office suite applications.
- Develop, institute, and practice employee education programs for identifying scams, malicious links, and attempted social engineering.
- Run regular penetration tests against the network, no less than once a year. Ideally, run these as often as possible and practical.
- Test your backups to ensure they work correctly upon use.
Recommendations for Network Protection
Apply the patch (MS17-010). If the patch cannot be applied, consider:
- Disabling SMBv1 and
- blocking all versions of SMB at the network boundary by blocking TCP port 445 with related protocols on UDP ports 137-138 and TCP port 139, for all boundary devices.
Note: disabling or blocking SMB may create problems by obstructing access to shared files, data, or devices. The benefits of mitigation should be weighed against potential disruptions to users.
Review US-CERT’s Alert on The Increasing Threat to Network Infrastructure Devices and Recommended Mitigations and consider implementing the following best practices:
- Segregate networks and functions.
- Limit unnecessary lateral communications.
- Harden network devices.
- Secure access to infrastructure devices.
- Perform out-of-band network management.
- Validate integrity of hardware and software.
Recommended Steps for Remediation
- Contact law enforcement. We strongly encourage you to contact a local FBI field office upon discovery to report an intrusion and request assistance. Maintain and provide relevant logs.
- Implement your security incident response and business continuity plan. Ideally, organizations should ensure they have appropriate backups so their response is simply to restore the data from a known clean backup.
Defending Against Ransomware Generally
Precautionary measures to mitigate ransomware threats include:
- Ensure anti-virus software is up-to-date.
- Implement a data back-up and recovery plan to maintain copies of sensitive or proprietary data in a separate and secure location. Backup copies of sensitive data should not be readily accessible from local networks.
- Scrutinize links contained in emails, and do not open attachments included in unsolicited emails.
- Only download software—especially free software—from sites you know and trust.
- Enable automated patches for your operating system and Web browser.
DHS and FBI encourages recipients who identify the use of tool(s) or techniques discussed in this document to report information to DHS or law enforcement immediately. We encourage you to contact DHS’s National Cybersecurity and Communications Integration Center (NCCIC) (NCCICcustomerservice@hq.dhs.gov or 888-282-0870), or the FBI through a local field office or the FBI’s Cyber Division (CyWatch@ic.fbi.gov or 855-292-3937) to report an intrusion and to request incident response resources or technical assistance.
- Malwarebytes LABS: WanaCrypt0r ransomware hits it big just before the weekend
- Malwarebytes LABS: The worm that spreads WanaCrypt0r
- Microsoft: Microsoft Security Bulletin MS17-010
- Forbes: An NSA Cyber Weapon Might Be Behind A Massive Global Ransomware Outbreak
- Reuters: Factbox: Don't click - What is the 'ransomware' WannaCry worm?
- GitHubGist: WannaCry|WannaDecrypt0r NSA-Cyberweapon-Powered Ransomware Worm
- Microsoft: Microsoft Update Catalog: Patches for Windows XP, Windows 8, and Windows Server 2003, (KB4012598)
- Cisco: Player 3 Has Entered the Game: Say Hello to 'WannaCry'
- Washington Post: More than 150 countries affected by massive cyberattack, Europol says
- May 12, 2017: Initial post
- May 14, 2017: Corrected Syntax in the second Yara Rule
- May 14, 2017: Added Microsoft link to patches for Windows XP, Windows 8, and Windows Server 2003
- May 14, 2017: Corrected Syntax in the first Yara Rule
- May 16, 2017: Provided further analysis and new IOCs in STIX format
- May 18, 2017: Provided initial IOCs in a STIX format
The National Cybersecurity and Communications Integration Center (NCCIC) has become aware of an emerging sophisticated campaign, occurring since at least May 2016, that uses multiple malware implants. Initial victims have been identified in several sectors, including Information Technology, Energy, Healthcare and Public Health, Communications, and Critical Manufacturing.
According to preliminary analysis, threat actors appear to be leveraging stolen administrative credentials (local and domain) and certificates, along with placing sophisticated malware implants on critical systems. Some of the campaign victims have been IT service providers, where credential compromises could potentially be leveraged to access customer environments. Depending on the defensive mitigations in place, the threat actor could possibly gain full access to networks and data in a way that appears legitimate to existing monitoring tools.
Although this activity is still under investigation, NCCIC is sharing this information to provide organizations information for the detection of potential compromises within their organizations.
NCCIC will update this document as information becomes available.
For a downloadable copy of this report and listings of IOCs, see:
To report activity related to this Incident Report Alert, please contact NCCIC at NCCICCustomerService@hq.dhs.gov or 1-888-282-0870.
NCCIC Cyber Incident Scoring System (NCISS) Rating Priority Level (Color)
A medium priority incident may affect public health or safety, national security, economic security, foreign relations, civil liberties, or public confidence.
While NCCIC continues to work with a variety of victims across different sectors, the adversaries in this campaign continue to affect several IT service providers. To achieve operational efficiencies and effectiveness, many IT service providers often leverage common core infrastructure that should be logically isolated to support multiple clients.
Intrusions into these providers create opportunities for the adversary to leverage stolen credentials to access customer environments within the provider network.
Figure 1: Structure of a traditional business network and an IT service provider network
The threat actors in this campaign have been observed employing a variety of tactics, techniques, and procedures (TTPs). The actors use malware implants to acquire legitimate credentials then leverage those credentials to pivot throughout the local environment. NCCIC is aware of several compromises involving the exploitation of system administrators’ credentials to access trusted domains as well as the malicious use of certificates. Additionally, the adversary makes heavy use of PowerShell and the open source PowerSploit tool to enable assessment, reconnaissance, and lateral movement.
Command and Control (C2) primarily occurs using RC4 cipher communications over port 443 to domains that change IP addresses. Many of these domains spoof legitimate sites and content, with a particular focus on spoofing Windows update sites. Most of the known domains leverage dynamic DNS services, and this pattern adds to the complexity of tracking this activity. Listings of observed domains are found in this document’s associated STIX package and .xlsx file. The indicators should be used to observe potential malicious activity on your network.
User impersonation via compromised credentials is the primary mechanism used by the adversary. However, a secondary technique to maintain persistence and provide additional access into the victim network is the use of malware implants left behind on key relay and staging machines. In some instances, the malware has only been found within memory with no on-disk evidence available for examination. To date, the actors have deployed multiple malware families and variants, some of which are currently not detected by anti-virus signatures. The observed malware includes PLUGX/SOGU and REDLEAVES. Although the observed malware is based on existing malware code, the actors have modified it to improve effectiveness and avoid detection by existing signatures.
Both REDLEAVES and PLUGX have been observed being executed on systems via dynamic-link library (DLL) side-loading. The DLL side-loading technique utilized by these malware families typically involves three files: a non-malicious executable, a malicious DLL loader, and an encoded payload file. The malicious DLL is named as one of the DLLs that the executable would normally load and is responsible for decoding and executing the payload into memory.
The most unique implant observed in this campaign is the REDLEAVES malware. The REDLEAVES implant consists of three parts: an executable, a loader, and the implant shellcode. The REDLEAVES implant is a remote administration Trojan (RAT) that is built in Visual C++ and makes heavy use of thread generation during its execution. The implant contains a number of functions typical of RATs, including system enumeration and creating a remote shell back to the C2.
System Enumeration. The implant is capable of enumerating the following information about the victim system and passing it back to the C2:
- system name,
- system architecture (x86 or x64),
- operating system major and minor versions,
- amount of available memory,
- processor specifications,
- language of the user,
- privileges of the current process,
- group permissions of the current user,
- system uptime,
- IP address, and
- primary drive storage utilization.
Command Execution. The implant can execute a command directly inside a command shell using native Windows functionality by passing the command to run to cmd.exe with the “/c” option (“cmd.exe /c <command>”).
Command Window Generation. The implant can also execute commands via a remote shell that is generated and passed through a named pipe. A command window is piped back to the C2 over the network as a remote shell or alternatively to another process or thread that can communicate with that pipe. The implant uses the mutexRedLeavesCMDSimulatorMutex.
File System Enumeration. The implant has the ability to enumerate data within a specified directory, where it gathers filenames, last file write times, and file sizes.
Network Traffic Compression and Encryption. The implant uses a form of LZO compression to compress data that is sent to its C2. After compression, the data for this implant sample is then RC4-ciphered with the key 0x6A6F686E3132333400 (this corresponds to the string “john1234” with the null byte appended).
Network Communications REDLEAVES connects to the C2 over TCP port 443, but does not use the secure flag when calling the API function InternetOpenUrlW. The data is not encrypted and there is no SSL handshake as would normally occur with port 443 traffic, but rather the data is transmitted in the form that is generated by the RC4 cipher.
Current REDLEAVES samples that have been examined have a hard-coded C2. Inside the implant’s configuration block in memory were the strings in Table 1.
While the name of the initial mutex, QN4869MD in this sample, varies among REDLEAVES samples, the RedLeavesCMDSimulatorMutex mutex name appears to be consistent. Table 2 contains a sample of the implant communications to the domain windowsupdates.dnset[.]com over TCP port 443.
Table 2: REDLEAVES Sample Beacon
REDLEAVES network traffic has two 12-byte fixed-length headers in front of each RC4-encrypted compressed payload. The first header comes in its own packet, with the second header and the payload following in a separate packet within the same TCP stream. The last four bytes of the first header contain the number of the remaining bytes in little-endian format (0x88 in the sample beacon above).
The second header, starting at position 0x0C, is XOR’d with the first four bytes of the key that is used to encrypt the payload. In the case of this sample, those first four bytes would be “john” (or 0x6a6f686e using the ASCII hex codes). After the XOR operation, the bytes in positions 0x0C through 0x0F contain the length of the decrypted and decompressed payload. The bytes in positions 0x10 through 0x13 contain the length of the encrypted and compressed payload.
To demonstrate, in the sample beacon, the second header follows:
0000000C 14 6f 68 6e 16 6f 68 6e c4 a4 b1 d1
The length of the decrypted and decompressed payload is 0x7e000000 in little-endian format (0x146f686e XOR 0x6a6f686e). The length of the encrypted and compressed payload is 0x7c000000 in little-endian (0x166f686e XOR 0x6a6f686e). This is verified by referring back to the sample beacon which had the number of remaining bytes set to 0x88 and subtracting the length of the second header (0x88 – 0xC = 0x7c).
Note: Use caution when searching based on strings, as common strings may cause a large number of false positives.
Table 3: Strings Appearing in the Analyzed Sample of REDLEAVES
Malware Execution Analysis
File Name: VeetlePlayer.exe
File Size: 25704 bytes (25.1 KB)
Description: This is the executable that calls the exports located within libvlc.dll
File Name: libvlc.dll
File Size: 33792 bytes (33.0 KB)
Description: This is the loader and decoder for mtcReport.ktc, the combined shellcode and implant file.
File Name: mtcReport.ktc
File Size: 231076 bytes (225.7 KB)
Description: This is the encoded shellcode and implant file. When this file is decoded, the shellcode precedes the actual implant, which resides at offset 0x1292 from the beginning of the shellcode in memory. The implant has the MZ and PE flags replaced with the value 0xFF.
All three of these files must be present for execution of the malware to succeed.
When all files are present and the VeetlePlayer.exe file is executed, it will make calls to the following DLL exports within the libvlc.dll file:
- VLC_Version checks to see if its calling file is named “VeetlePlayer.exe”. If the calling file is named something else, execution will terminate and no shellcode will be loaded.
- VLC_Create reads in the contents of the file mtcReport.ktc.
- VLC_Init takes in the offset in which the encoded shellcode/implant file is located and deobfuscates it. After deobfuscation, this export executes the shellcode.
- VLC_Destroy does nothing other than perform a return 0.
- VLC_AddIntf and VLC_CleanUp simply call the export VLC_Destroy, which returns 0.
When the libvlc.dll decodes the shellcode/implant, it calls the shellcode at the beginning of the data blob in memory. The shellcode then activates a new instance of svchost.exe and suspends it. It then makes a call to WriteProcessMemory() and inserts the implant with the damaged MZ and PE headers into its memory space. It then resumes execution of svchost.exe, which runs the implant.
The resulting decoded shellcode with the implant file below it can have a variable MD5 based on how it is dumped from memory. The MD5 checksums of two instances of decoded shellcode are:
Table 4 contains the implant resulting from the original implant’s separation from the shellcode and the repair of its MZ and PE flags.
Table 4: Resulting Implant from Shellcode Separation
PLUGX is a sophisticated Remote Access Tool (RAT) operating since approximately 2012. Although there are now many variants of this RAT in existence today, there are still characteristics common to most variants.
Typically, PLUGX uses three components to install itself.
- A non-malicious executable
- A malicious DLL/installer
- An encoded payload – the PLUGX RAT.
A non-malicious executable with one or more imports is used to start the installation process. The executable will likely exist in a directory not normally associated with its use. In some cases, the actor may use an executable signed with a valid certificate, and rename the DLL and encoded payload with file names that suggest they are related to the trusted file. Importantly, the actor seems to vary the encoding scheme used to protect the encoded payload to stifle techniques used by AV vendors to develop patterns to detect it. The payload is either encoded with a single byte or encrypted and decompressed. Recently, NCCIC has observed a case where the encoded payload contains a decoding stub within itself, beginning at byte zero. The malware simply reads this payload and executes it starting at byte zero. The stub then decodes and executes the rest of itself in memory. Notably, this stub varies in its structure and algorithm, again stifling detection by signature based security software. The PLUGX malware is never stored on disk in an unencrypted or decoded format.
When the initial executable is launched, the imported library, usually a separate DLL, is replaced with a malicious version that in turn decodes and installs the third and final component, which is the PLUGX rat itself. Typically, the PLUGX component is obfuscated and contains no visible executable code until it is unpacked in memory, protecting it from AV/YARA scans while static. During the evolution of these PLUGX compromises, NCCIC noted an increasing implementation of protections of the actual decoded PLUGX in memory. For example, the most recent version we looked at implements a secure strings method, which hides the majority of the common commands used by PLUGX. This is an additional feature designed to thwart signature based security tools.
Once the PLUGX RAT is installed on the victim, the actors has complete C2 capabilities of the victim system, including the ability to take screenshots and download files from the compromised system. The communications between the RAT (installed on the victim system) and the PLUGX C2 server are encoded to secure the communication and stifle detection by signature based network signature tools.
The advanced capabilities of PLUGX are implemented via a plugin framework. Each plugin operates independently in its own unique thread within the service. The modules may vary based on variants. Table 5 lists the modules and capabilities contained within one sample recently analyzed by NCCIC.
Table 5: Modules and Capabilities of PLUGX
wide range of system-related capabilities including file / directory / drive enumeration, file / directory creation, create process, and obtain environment variables
logs keystrokes and saves data to log file
enumerates the host's network resources via the Windows multiple provider router DLL
set the state of a TCP connection or obtain the extended TCP or UDP tables (lists of network endpoints available to a process) of each active process on the host
provides the ability to initiate a system shutdown, adjust shutdown-related privileges for a given process, and lock the user's workstation
process enumeration, termination, and capability to obtain more in-depth information pertaining to each process (e.g. CompanyName, FileDescription, FileVersion of each module loaded by the process)
create, read, update & delete registry entries
capability to capture screenshots of the system
start, stop, remove, configure & query services
remote shell access
enumerate SQL databases and available drivers; execute SQL queries
provides a telnet interface
The PLUGX operator may dynamically add, remove, or update PLUGX plugins during runtime. This provides the ability to dynamically adjust C2 capabilities based on the requirements of the C2 operator.
Network activity is often seen as POST requests similar to that shown in table 6. Network defenders can look to detect non-SSL HTTP traffic on port 443, which can be indicative of malware traffic. The PLUGX malware is also seen using TCP ports 80, 8080, and 53.
Table 6: Sample PLUGX Beacon
Even though the beacon went to port 443, which is commonly used for encrypted HTTP communications, this traffic was plaintext HTTP, as is common for this variant of PLUGX.
For IT Service Providers
All organizations that provide IT services as a commodity for other organizations should evaluate their infrastructure to determine if related activity has taken place. Active monitoring of network traffic for the indicators of compromise (IOCs) provided in this report, as well as behavior analysis for similar activity, should be conducted to identify C2 traffic. In addition, frequency analysis should be conducted at the lowest level possible to determine any unusual fluctuation in bandwidth indicative of a potential data exfiltration. Both management and client systems should be evaluated for host indicators provided. If an intrusion is suspected, please reach out to the NCCIC at the contact information provided at the end of this report.
For Private Organizations and Government Agencies
All organizations should include the IOCs provided in their normal intrusion detection systems for continual analysis. Organizations that determine their risk to be elevated due to alignment to the sectors being targeted, unusual detected activity, or other factors, should conduct a dedicated investigation to identify any related activity. Organizations which leverage external IT service providers should validate with their providers that due diligence is being conducted to validate if there are security concerns with their specific provider. If an intrusion is suspected, please reach out to the NCCIC at the contact information provided at the end of this report.
NCCIC is providing a compilation of IOCs from a variety of sources to aid in the detection of this malware. The IOCs provided in the associated STIX package and .xlsx file were derived from various government, commercial, and publically available sources. The sources provided does not constitute an exhaustive list and the U.S. Government does not endorse or support any particular product or vendor’s information listed in this report. However, NCCIC includes this compilation here to ensure the distribution of the most comprehensive information. This alert will be updated as additional details become available.
Table 7: Sources Referenced
“menuPass Returns with New Malware and New Attacks Against Japanese Academics and Organizations”
“APT10 (Menupass Team) Renews Operations Focused on Nordic Private Industry; operations Extend to Global Partners”. February 23, 2017 10:14:00 AM,17-00001858, Version: 2
“The Deception Project: A New Japanese-Centric Threat”
“Operation Cloud Hopper: Exposing a systematic hacking operation with an
unprecedented web of global victims: April 2017”
“RedLeaves-Malware Based on Open Source Rat”
National Cyber Security Centre
“Infrastructure Update Version 1.0” Reference: March 17, 2017
“BUGJUICE Malware Profile”. April 05, 2017 11:45:00 AM, 17-00003261, Version: 1
“ChChes- Malware that Communicates with C&C Servers Using Cookie Headers”
NCCIC recommends monitoring activity to the following domains and IP addresses, and scanning for evidence of the file hashes as potential indicators of infection. Some of the IOCs provided may be associated with legitimate traffic. Nevertheless, closer evaluation is warranted if the IOCs are observed. If these IOCs are found, NCCIC can provide additional assistance in further investigations. A comprehensive listing of IOCs can be found in the associated STIX package and .xlsx file.
Table 8: REDLEAVES Network Signatures
Table 9: REDLEAVES YARA Signatures
Table 10: PLUGX Network Signatures
Table 11: PLUGX and REDLEAVES YARA Signatures
Other Detection Methods
Examine Port/Protocol Mismatches: Examine network traffic where the network port and protocol do not match, such as plaintext HTTP over port 443.
Administrative Share Mapping: When a malicious actor tries to move laterally on a network, one of the techniques is to mount administrative shares to perform operations like uploading and downloading resources or executing commands. In addition, tools like System Internals PSEXEC will mount the shares automatically for the user. Since administrators may map administrative shares legitimately while managing components of the network, this must be taken into account.
- Filter network traffic for SMB mapping events and group the events by source IP, destination IP, the mounted path (providing a count of total mounts to that path), the first map time, and the last map time
- Collect Windows Event Logs – Event ID 5140 (network share object was accessed) can be used to track C$ and ADMIN$ mounts by searching the Share Name field
VPN User authentication mismatch: A VPN user authentication match occurs when a user account authenticates to an IP address but once connected the internal IP address requests authentication tokens for other users. This may create false positives for legitimate network administrators but if this is detected, organizations should verify that the administrative accounts were legitimately used.
VPN activity from VPS providers: While this may also produce false positives, VPN logins from Virtual Private Server (VPS) providers may be an indicator of VPN users attempting to hide their source IP and should be investigated.
A successful network intrusion can have severe impacts, particularly if the compromise becomes public and sensitive information is exposed. Possible impacts include:
- temporary or permanent loss of sensitive or proprietary information,
- disruption to regular operations,
- financial losses incurred to restore systems and files, and
- potential harm to an organization’s reputation.
Properly implemented defensive techniques and programs make it more difficult for an adversary to gain access to a network and remain persistent yet undetected. When an effective defensive program is in place, actors should encounter complex defensive barriers. Actor activity should also trigger detection and prevention mechanisms that enable organizations to contain and respond to the intrusion more rapidly. There is no single or set of defensive techniques or programs that will completely avert all malicious activities. Multiple defensive techniques and programs should be adopted and implemented in a layered approach to provide a complex barrier to entry, increase the likelihood of detection, and decrease the likelihood of a successful compromise. This layered mitigation approach is known as defense-in-depth.
NCCIC mitigations and recommendations are based on observations made during the hunt, analysis, and network monitoring for threat actor activity, combined with client interaction.
- Enable application directory whitelisting through Microsoft Software Restriction Policy (SRP) or AppLocker;
- Use directory whitelisting rather than trying to list every possible permutation of applications in an environment. Safe defaults allow applications to run from PROGRAMFILES, PROGRAMFILES(X86), and SYSTEM32. All other locations should be disallowed unless an exception is granted.
- Prevent the execution of unauthorized software by using application whitelisting as part of the security hardening of operating systems insulating.
- Enable application directory whitelisting via the Microsoft SRP or AppLocker.
- Decrease a threat actor’s ability to access key network resources by implementing the principle of least privilege.
- Limit the ability of a local administrator account to login from a local interactive session (e.g., “Deny access to this computer from the network”) and prevent access via a Remote Desktop Protocol session.
- Remove unnecessary accounts, groups, and restrict root access.
- Control and limit local administration.
- Make use of the Protected Users Active Directory group in Windows Domains to further secure privileged user accounts against pass-the-hash compromises.
- Create a secure system baseline image and deploy to all workstations.
- Mitigate potential exploitation by threat actors by following a normal patching cycle for all operating systems, applications, software, and all third-party software.
- Apply asset and patch management processes.
- Reduce the number of cached credentials to one if a laptop, or zero if a desktop or fixed asset.
Host-Based Intrusion Detection
- Configure and monitor system logs through host-based intrusion detection system (HIDS) and firewall.
- Deploy an anti-malware solution to prevent spyware, adware, and malware as part of the operating system security baseline.
- Monitor antivirus scan results on a regular basis.
- Create a secure system baseline image, and deploy to all servers.
- Upgrade or decommission end-of-life non Windows servers.
- Upgrade or decommission servers running Windows Server 2003 and older versions.
- Implement asset and patch management processes.
- Audit for and disable unnecessary services.
Server Configuration and Logging
- Establish remote server logging and retention.
- Reduce the number of cached credentials to zero.
- Configure and monitor system logs via a centralized security information and event management (SIEM) appliance.
- Add an explicit DENY for “%USERPROFILE%”.
- Restrict egress web traffic from servers.
- In Windows environments, utilize Restricted Admin mode or remote credential guard to further secure remote desktop sessions against pass-the-hash compromises.
- Restrict anonymous shares.
- Limit remote access by only using jump servers for such access.
- Create a change control process for all implemented changes.
- An Intrusion Detection System (IDS) should:
- Implement continuous monitoring.
- Send alerts to a SIEM tool.
- Monitor internal activity (this tool may use the same tap points as the netflow generation tools).
- Netflow Capture should:
- Set a minimum retention period of 180 days.
- Capture netflow on all ingress and egress points of network segments, not just at the Managed Trusted Internet Protocol Services (MTIPS) or Trusted Internet Connections (TIC) locations.
- Network Packet Capture (PCAP):
- Retain PCAP data for a minimum of 24 hours.
- Capture traffic on all ingress and egress points of the network.
- Use a virtual private network (VPN):
- Maintain site-to-site VPN with customers.
- Authenticate users utilizing site-to-site VPNs through adaptive security appliance (ASA).
- Use authentication, authorization, and accounting (AAA) for controlling network access.
- Require Personal Identity Verification (PIV) authentication to an HTTPS page on the ASA in order to control access. Authentication should also require explicit rostering of PIV distinguished names (DNs) that are permitted to enhance the security posture on both networks participating in the site-to-site VPN.
- Establish appropriate secure tunneling protocol and encryption.
- Strengthen router configuration (e.g., avoid enabling remote management over the Internet and using default IP ranges; automatically logout after configuring routers; use encryption).
- Turn off Wi-Fi protected setup (WPS), enforce the use of strong passwords, keep router firmware up-to-date; and
- Improve firewall security (e.g., enable auto updates, revise firewall rules as appropriate, implement whitelists, establish packet filtering, enforce the use of strong passwords, and encrypt networks).
- Conduct regular vulnerability scans of the internal and external networks and hosted content to identify and mitigate vulnerabilities.
- Define areas within the network that should be segmented to increase visibility of lateral movement by an adversary and increase the defense in-depth posture.
- Develop a process to block traffic to IP addresses and domain names that have been identified as being used to aid previous malicious activities.
Network Infrastructure Recommendations
- Ensure you are following National Security Agency (NSA) network device integrity (NDI) best practices.
- Ensure your networking equipment has the latest available operating system and patches.
- Implement policies to block workstations-to-workstation remote desktop protocol (RDP) connections through group policy object (GPO) on Windows, or a similar mechanism.
- Store system logs of mission critical systems for at least one year within a SIEM.
- Review the configuration of application logs to verify fields being recorded will contribute to an incident response investigation.
- Immediately set the password policy to require complex passwords for all users (minimum of 15 characters); this new requirement should be enforced as user passwords expire.
- Reduce the number of domain and enterprise administrator accounts.
- Create non-privileged accounts for privileged users and ensure they use the non-privileged account for all non-privileged access (e.g., web browsing, email access);
- If possible, use technical methods to detect or prevent browsing by privileged accounts (authentication to web proxies would enable blocking of domain administrators).
- Use two-factor authentication (e.g., security tokens for remote access and to any sensitive data repositories);
- If soft tokens are used, they should not exist on the same device that is requesting remote access (laptop), and instead should be on a telephone or other out-of-band device.
- Create privileged role tracking;
- Create a change control process to all privilege escalations and role changes on user accounts;
- Enable alerts on privilege escalations and role changes; and
- Log privileged user changes in the environment and alert on unusual events.
- Establish least privilege controls; and
- Implement a security-awareness training program.
- Implement a vulnerability assessment and remediation program.
- Encrypt all sensitive data in transit and at rest.
- Create an insider threat program.
- Assign additional personnel to review logging and alerting data.
- Complete independent security (not compliance) audit.
- Create an information sharing program.
- Complete and maintain network and system documentation to aid in timely incident response, including:
- network diagrams,
- asset owners,
- type of asset, and
- an up-to-date incident response plan.
- PaloAltoNetworks: “menuPass Returns with New Malware and New Attacks Against Japanese Academics and Organizations”
- FireEye: “APT10 (Menupass Team) Renews Operations Focused on Nordic Private Industry; operations Extend to Global Partners”. Feb
- CyLance: “The Deception Project: A New Japanese-Centric Threat”
- PwC/BAE Systems: “Operation Cloud Hopper: Exposing a systematic hacking operation with an unprecedented web of global victims: A
- JPCERT/CC: “RedLeaves-Malware Based on Open Source Rat”
- NCC Group: “RedLeaves Implant-Overview”
- National Cyber Security Centre: “Infrastructure Update Version 1.0" Reference: March 17, 2017”
- FireEye: “BUGJUICE Malware Profile”. April 05, 2017 11:45:00 AM, 17-00003261, Version: 1
- JPCERT/CC: “ChChes- Malware that Communicates with C&C Servers Using Cookie Headers”
- April 27, 2017: Initial post
- April 28, 2017: Updated guidance under the sub-section: Network Infrastructure Recommendations
- May 2, 2017: In table 11, fixed trailing quote on date
- May 11, 2017: STIX and XLSX package was updated
All systems behind a hypertext transfer protocol secure (HTTPS) interception product are potentially affected.
Many organizations use HTTPS interception products for several purposes, including detecting malware that uses HTTPS connections to malicious servers. The CERT Coordination Center (CERT/CC) explored the tradeoffs of using HTTPS interception in a blog post called The Risks of SSL Inspection .
Organizations that have performed a risk assessment and determined that HTTPS inspection is a requirement should ensure their HTTPS inspection products are performing correct transport layer security (TLS) certificate validation. Products that do not properly ensure secure TLS communications and do not convey error messages to the user may further weaken the end-to-end protections that HTTPS aims to provide.
TLS and its predecessor, Secure Sockets Layer (SSL), are important Internet protocols that encrypt communications over the Internet between the client and server. These protocols (and protocols that make use of TLS and SSL, such as HTTPS) use certificates to establish an identity chain showing that the connection is with a legitimate server verified by a trusted third-party certificate authority.
HTTPS inspection works by intercepting the HTTPS network traffic and performing a man-in-the-middle (MiTM) attack on the connection. In MiTM attacks, sensitive client data can be transmitted to a malicious party spoofing the intended server. In order to perform HTTPS inspection without presenting client warnings, administrators must install trusted certificates on client devices. Browsers and other client applications use this certificate to validate encrypted connections created by the HTTPS inspection product. In addition to the problem of not being able to verify a web server’s certificate, the protocols and ciphers that an HTTPS inspection product negotiates with web servers may also be invisible to a client. The problem with this architecture is that the client systems have no way of independently validating the HTTPS connection. The client can only verify the connection between itself and the HTTPS interception product. Clients must rely on the HTTPS validation performed by the HTTPS interception product.
A recent report, The Security Impact of HTTPS Interception , highlighted several security concerns with HTTPS inspection products and outlined survey results of these issues. Many HTTPS inspection products do not properly verify the certificate chain of the server before re-encrypting and forwarding client data, allowing the possibility of a MiTM attack. Furthermore, certificate-chain verification errors are infrequently forwarded to the client, leading a client to believe that operations were performed as intended with the correct server. This report provided a method to allow servers to detect clients that are having their traffic manipulated by HTTPS inspection products. The website badssl.com  is a resource where clients can verify whether their HTTPS inspection products are properly verifying certificate chains. Clients can also use this site to verify whether their HTTPS inspection products are enabling connections to websites that a browser or other client would otherwise reject. For example, an HTTPS inspection product may allow deprecated protocol versions or weak ciphers to be used between itself and a web server. Because client systems may connect to the HTTPS inspection product using strong cryptography, the user will be unaware of any weakness on the other side of the HTTPS inspection.
Because the HTTPS inspection product manages the protocols, ciphers, and certificate chain, the product must perform the necessary HTTPS validations. Failure to perform proper validation or adequately convey the validation status increases the probability that the client will fall victim to MiTM attacks by malicious third parties.
Organizations using an HTTPS inspection product should verify that their product properly validates certificate chains and passes any warnings or errors to the client. A partial list of products that may be affected is available at The Risks of SSL Inspection . Organizations may use badssl.com  as a method of determining if their preferred HTTPS inspection product properly validates certificates and prevents connections to sites using weak cryptography. At a minimum, if any of the tests in the Certificate section of badssl.com prevent a client with direct Internet access from connecting, those same clients should also refuse the connection when connected to the Internet by way of an HTTPS inspection product.
In general, organizations considering the use of HTTPS inspection should carefully consider the pros and cons of such products before implementing . Organizations should also take other steps to secure end-to-end communications, as presented in US-CERT Alert TA15-120A .
Note: The U.S. Government does not endorse or support any particular product or vendor.
- The Risks of SSL Inspection
- The Security Impact of HTTPS Interception
- Securing End-to-End Communications
- March 16, 2017: intial post
“Avalanche” refers to a large global network hosting infrastructure used by cyber criminals to conduct phishing and malware distribution campaigns and money mule schemes. The United States Department of Homeland Security (DHS), in collaboration with the Federal Bureau of Investigation (FBI), is releasing this Technical Alert to provide further information about Avalanche.
Cyber criminals utilized Avalanche botnet infrastructure to host and distribute a variety of malware variants to victims, including the targeting of over 40 major financial institutions. Victims may have had their sensitive personal information stolen (e.g., user account credentials). Victims’ compromised systems may also have been used to conduct other malicious activity, such as launching denial-of-service (DoS) attacks or distributing malware variants to other victims’ computers.
In addition, Avalanche infrastructure was used to run money mule schemes where criminals recruited people to commit fraud involving transporting and laundering stolen money or merchandise.
Avalanche used fast-flux DNS, a technique to hide the criminal servers, behind a constantly changing network of compromised systems acting as proxies.
The following malware families were hosted on the infrastructure:
- Windows-encryption Trojan horse (WVT) (aka Matsnu, Injector,Rannoh,Ransomlock.P)
- URLzone (aka Bebloh)
- VM-ZeuS (aka KINS)
- Bugat (aka Feodo, Geodo, Cridex, Dridex, Emotet)
- newGOZ (aka GameOverZeuS)
- Tinba (aka TinyBanker)
- Vawtrak (aka Neverquest)
- Smart App
- iBanking Trusteer App Trojan
Avalanche was also used as a fast flux botnet which provides communication infrastructure for other botnets, including the following:
- QakBot (aka Qbot, PinkSlip Bot)
A system infected with Avalanche-associated malware may be subject to malicious activity including the theft of user credentials and other sensitive data, such as banking and credit card information. Some of the malware had the capability to encrypt user files and demand a ransom be paid by the victim to regain access to those files. In addition, the malware may have allowed criminals unauthorized remote access to the infected computer. Infected systems could have been used to conduct distributed denial-of-service (DDoS) attacks.
Users are advised to take the following actions to remediate malware infections associated with Avalanche:
- Use and maintain anti-virus software – Anti-virus software recognizes and protects your computer against most known viruses. Even though parts of Avalanche are designed to evade detection, security companies are continuously updating their software to counter these advanced threats. Therefore, it is important to keep your anti-virus software up-to-date. If you suspect you may be a victim of an Avalanche malware, update your anti-virus software definitions and run a full-system scan. (See Understanding Anti-Virus Software for more information.)
- Avoid clicking links in email – Attackers have become very skilled at making phishing emails look legitimate. Users should ensure the link is legitimate by typing the link into a new browser (see Avoiding Social Engineering and Phishing Attacks for more information).
- Change your passwords – Your original passwords may have been compromised during the infection, so you should change them. (See Choosing and Protecting Passwords for more information.)
- Keep your operating system and application software up-to-date – Install software patches so that attackers cannot take advantage of known problems or vulnerabilities. You should enable automatic updates of the operating system if this option is available. (See Understanding Patches for more information.)
- Use anti-malware tools – Using a legitimate program that identifies and removes malware can help eliminate an infection. Users can consider employing a remediation tool. A non-exhaustive list of examples is provided below. The U.S. Government does not endorse or support any particular product or vendor.
ESET Online Scanner
Microsoft Safety Scanner
Norton Power Eraser
Trend Micro HouseCall
- December 1, 2016: Initial release
- December 2, 2016: Added TrendMicro Scanner
Internet of Things (IoT)—an emerging network of devices (e.g., printers, routers, video cameras, smart TVs) that connect to one another via the Internet, often automatically sending and receiving data
Recently, IoT devices have been used to create large-scale botnets—networks of devices infected with self-propagating malware—that can execute crippling distributed denial-of-service (DDoS) attacks. IoT devices are particularly susceptible to malware, so protecting these devices and connected hardware is critical to protect systems and networks.
On September 20, 2016, Brian Krebs’ security blog (krebsonsecurity.com) was targeted by a massive DDoS attack, one of the largest on record, exceeding 620 gigabits per second (Gbps).[1 (link is external)] An IoT botnet powered by Mirai malware created the DDoS attack. The Mirai malware continuously scans the Internet for vulnerable IoT devices, which are then infected and used in botnet attacks. The Mirai bot uses a short list of 62 common default usernames and passwords to scan for vulnerable devices. Because many IoT devices are unsecured or weakly secured, this short dictionary allows the bot to access hundreds of thousands of devices.[2 (link is external)] The purported Mirai author claimed that over 380,000 IoT devices were enslaved by the Mirai malware in the attack on Krebs’ website.[3 (link is external)]
In late September, a separate Mirai attack on French webhost OVH broke the record for largest recorded DDoS attack. That DDoS was at least 1.1 terabits per second (Tbps), and may have been as large as 1.5 Tbps.[4 (link is external)]
The IoT devices affected in the latest Mirai incidents were primarily home routers, network-enabled cameras, and digital video recorders.[5 (link is external)] Mirai malware source code was published online at the end of September, opening the door to more widespread use of the code to create other DDoS attacks.
In early October, Krebs on Security reported on a separate malware family responsible for other IoT botnet attacks.[6 (link is external)] This other malware, whose source code is not yet public, is named Bashlite. This malware also infects systems through default usernames and passwords. Level 3 Communications, a security firm, indicated that the Bashlite botnet may have about one million enslaved IoT devices.[7 (link is external)]
With the release of the Mirai source code on the Internet, there are increased risks of more botnets being generated. Both Mirai and Bashlite can exploit the numerous IoT devices that still use default passwords and are easily compromised. Such botnet attacks could severely disrupt an organization’s communications or cause significant financial harm.
Software that is not designed to be secure contains vulnerabilities that can be exploited. Software-connected devices collect data and credentials that could then be sent to an adversary’s collection point in a back-end application.
In late November 2016, a new Mirai-derived malware attack actively scanned TCP port 7547 on broadband routers susceptible to a Simple Object Access Protocol (SOAP) vulnerability. [8 (link is external)] Affected routers use protocols that leave port 7547 open, which allows for exploitation of the router. These devices can then be remotely used in DDoS attacks. [9, 10 (links are external)]
Cybersecurity professionals should harden networks against the possibility of a DDoS attack. For more information on DDoS attacks, please refer to US-CERT Security Publication DDoS Quick Guide and the US-CERT Alert on UDP-Based Amplification Attacks.
In order to remove the Mirai malware from an infected IoT device, users and administrators should take the following actions:
- Disconnect device from the network.
- While disconnected from the network and Internet, perform a reboot. Because Mirai malware exists in dynamic memory, rebooting the device clears the malware [11 (link is external)].
- Ensure that the password for accessing the device has been changed from the default password to a strong password. See US-CERT Tip Choosing and Protecting Passwords for more information.
- You should reconnect to the network only after rebooting and changing the password. If you reconnect before changing the password, the device could be quickly reinfected with the Mirai malware.
In order to prevent a malware infection on an IoT device, users and administrators should take following precautions:
- Ensure all default passwords are changed to strong passwords. Default usernames and passwords for most devices can easily be found on the Internet, making devices with default passwords extremely vulnerable.
- Update IoT devices with security patches as soon as patches become available.
- Disable Universal Plug and Play (UPnP) on routers unless absolutely necessary.[12 (link is external)]
- Purchase IoT devices from companies with a reputation for providing secure devices.
- Consumers should be aware of the capabilities of the devices and appliances installed in their homes and businesses. If a device comes with a default password or an open Wi-Fi connection, consumers should change the password and only allow it to operate on a home network with a secured Wi-Fi router.
- Understand the capabilities of any medical devices intended for at-home use. If the device transmits data or can be operated remotely, it has the potential to be infected.
- Monitor Internet Protocol (IP) port 2323/TCP and port 23/TCP for attempts to gain unauthorized control over IoT devices using the network terminal (Telnet) protocol.[13 (link is external)]
- Look for suspicious traffic on port 48101. Infected devices often attempt to spread malware by using port 48101 to send results to the threat actor.
-  KrebsOnSecurity: KrebsOnSecurity Hit With Record DDoS
-  Sophos: Mirai “internet of things” malware from Krebs DDoS attack goes open source
-  PCWorld: Smart device malware behind record DDoS attack is now available to all hackers
-  ArsTechnica: Record-breaking DDoS reportedly delivered by >145k hacked cameras
-  InformationWeek DarkReading: IoT DDoS Attack Code Released
-  KrebsOnSecurity: Source Code for IoT Botnet "Mirai" Released
-  Level 3 Threat Research Labs: Attack of Things!
-  SANS ISC InfoSec Forums: Port 7547 SOAP Remote Code Execution Attack Against DSL Modems
-  ArsTechnica: Newly Discovered Router Flaw Being Hammered by In-The-Wild Attacks
-  Network Security Research Lab: A Few Observations of The New Mirai Variant on Port 7547
-  ICS-CERT: Sierra Wireless Mitigations Against Mirai Malware
-  Federal Bureau of Investigation Public Service Announcement: Internet of Things Poses Opportunities for Cyber Crime
-  SANS ISC InfoSec Forums: What is happening on 2323/TCP?
- October 14, 2016: Initial release
- October 17, 2016: Added ICS-CERT reference 
- November 30, 2016: Added SOAP vulnerability references , , 
Network Infrastructure Devices
The advancing capabilities of organized hacker groups and cyber adversaries create an increasing global threat to information systems. The rising threat levels place more demands on security personnel and network administrators to protect information systems. Protecting the network infrastructure is critical to preserve the confidentiality, integrity, and availability of communication and services across an enterprise.
To address threats to network infrastructure devices, this Alert provides information on recent vectors of attack that advanced persistent threat (APT) actors are targeting, along with prevention and mitigation recommendations.
Network infrastructure consists of interconnected devices designed to transport communications needed for data, applications, services, and multi-media. Routers and firewalls are the focus of this alert; however, many other devices exist in the network, such as switches, load-balancers, intrusion detection systems, etc. Perimeter devices, such as firewalls and intrusion detection systems, have been the traditional technologies used to secure the network, but as threats change, so must security strategies. Organizations can no longer rely on perimeter devices to protect the network from cyber intrusions; organizations must also be able to contain the impact/losses within the internal network and infrastructure.
For several years now, vulnerable network devices have been the attack-vector of choice and one of the most effective techniques for sophisticated hackers and advanced threat actors. In this environment, there has never been a greater need to improve network infrastructure security. Unlike hosts that receive significant administrative security attention and for which security tools such as anti-malware exist, network devices are often working in the background with little oversight—until network connectivity is broken or diminished. Malicious cyber actors take advantage of this fact and often target network devices. Once on the device, they can remain there undetected for long periods. After an incident, where administrators and security professionals perform forensic analysis and recover control, a malicious cyber actor with persistent access on network devices can reattack the recently cleaned hosts. For this reason, administrators need to ensure proper configuration and control of network devices.
Proliferation of Threats to Information Systems
In September 2015, an attack known as SYNful Knock was disclosed. SYNful Knock silently changes a router’s operating system image, thus allowing attackers to gain a foothold on a victim’s network. The malware can be customized and updated once embedded. When the modified malicious image is uploaded, it provides a backdoor into the victim’s network. Using a crafted TCP SYN packet, a communication channel is established between the compromised device and the malicious command and control (C2) server. The impact of this infection to a network or device is severe and most likely indicates that there may be additional backdoors or compromised devices on the network. This foothold gives an attacker the ability to maneuver and infect other hosts and access sensitive data.
The initial infection vector does not leverage a zero-day vulnerability. Attackers either use the default credentials to log into the device or obtain weak credentials from other insecure devices or communications. The implant resides within a modified IOS image and, when loaded, maintains its persistence in the environment, even after a system reboot. Any further modules loaded by the attacker will only exist in the router’s volatile memory and will not be available for use after the device reboots. However, these devices are rarely or never rebooted.
To prevent the size of the image from changing, the malware overwrites several legitimate IOS functions with its own executable code. The attacker examines the functionality of the router and determines functions that can be overwritten without causing issues on the router. Thus, the overwritten functions will vary upon deployment.
The attacker can utilize the secret backdoor password in three different authentication scenarios. In these scenarios the implant first checks to see if the user input is the backdoor password. If so, access is granted. Otherwise, the implanted code will forward the credentials for normal verification of potentially valid credentials. This generally raises the least amount of suspicion. Cisco has provided an alert on this attack vector. For more information, see the Cisco SYNful Knock Security Advisory.
Other attacks against network infrastructure devices have also been reported, including more complicated persistent malware that silently changes the firmware on the device that is used to load the operating system so that the malware can inject code into the running operating system. For more information, please see Cisco's description of the evolution of attacks on Cisco IOS devices.
Cisco Adaptive Security Appliance (ASA)
A Cisco ASA device is a network device that provides firewall and Virtual Private Network (VPN) functionality. These devices are often deployed at the edge of a network to protect a site’s network infrastructure, and to give remote users access to protected local resources.
In June 2016, NCCIC received several reports of compromised Cisco ASA devices that were modified in an unauthorized way. The ASA devices directed users to a location where malicious actors tried to socially engineer the users into divulging their credentials.
It is suspected that malicious actors leveraged CVE-2014-3393 to inject malicious code into the affected devices. The malicious actor would then be able to modify the contents of the Random Access Memory Filing System (RAMFS) cache file system and inject the malicious code into the appliance’s configuration. Refer to the Cisco Security Advisory Multiple Vulnerabilities in Cisco ASA Software for more information and for remediation details.
In August 2016, a group known as “Shadow Brokers” publicly released a large number of files, including exploitation tools for both old and newly exposed vulnerabilities. Cisco ASA devices were found to be vulnerable to the released exploit code. In response, Cisco released an update to address a newly disclosed Cisco ASA Simple Network Management Protocol (SNMP) remote code execution vulnerability (CVE-2016-6366). In addition, one exploit tool targeted a previously patched Cisco vulnerability (CVE-2016-6367). Although Cisco provided patches to fix this Cisco ASA command-line interface (CLI) remote code execution vulnerability in 2011, devices that remain unpatched are still vulnerable to the described attack. Attackers may target vulnerabilities for months or even years after patches become available.
If the network infrastructure is compromised, malicious hackers or adversaries can gain full control of the network infrastructure enabling further compromise of other types of devices and data and allowing traffic to be redirected, changed, or denied. Possibilities of manipulation include denial-of-service, data theft, or unauthorized changes to the data.
Intruders with infrastructure privilege and access can impede productivity and severely hinder re-establishing network connectivity. Even if other compromised devices are detected, tracking back to a compromised infrastructure device is often difficult.
Malicious actors with persistent access to network devices can reattack and move laterally after they have been ejected from previously exploited hosts.
1. Segregate Networks and Functions
Proper network segmentation is a very effective security mechanism to prevent an intruder from propagating exploits or laterally moving around an internal network. On a poorly segmented network, intruders are able to extend their impact to control critical devices or gain access to sensitive data and intellectual property. Security architects must consider the overall infrastructure layout, segmentation, and segregation. Segregation separates network segments based on role and functionality. A securely segregated network can contain malicious occurrences, reducing the impact from intruders, in the event that they have gained a foothold somewhere inside the network.
Physical Separation of Sensitive Information
Local Area Network (LAN) segments are separated by traditional network devices such as routers. Routers are placed between networks to create boundaries, increase the number of broadcast domains, and effectively filter users’ broadcast traffic. These boundaries can be used to contain security breaches by restricting traffic to separate segments and can even shut down segments of the network during an intrusion, restricting adversary access.
- Implement Principles of Least Privilege and need-to-know when designing network segments.
- Separate sensitive information and security requirements into network segments.
- Apply security recommendations and secure configurations to all network segments and network layers.
Virtual Separation of Sensitive Information
As technologies change, new strategies are developed to improve IT efficiencies and network security controls. Virtual separation is the logical isolation of networks on the same physical network. The same physical segmentation design principles apply to virtual segmentation but no additional hardware is required. Existing technologies can be used to prevent an intruder from breaching other internal network segments.
- Use Private Virtual LANs to isolate a user from the rest of the broadcast domains.
- Use Virtual Routing and Forwarding (VRF) technology to segment network traffic over multiple routing tables simultaneously on a single router.
- Use VPNs to securely extend a host/network by tunneling through public or private networks.
2. Limit Unnecessary Lateral Communications
Allowing unfiltered workstation-to-workstation communications (as well as other peer-to-peer communications) creates serious vulnerabilities, and can allow a network intruder to easily spread to multiple systems. An intruder can establish an effective “beach head” within the network, and then spread to create backdoors into the network to maintain persistence and make it difficult for defenders to contain and eradicate.
- Restrict communications using host-based firewall rules to deny the flow of packets from other hosts in the network. The firewall rules can be created to filter on a host device, user, program, or IP address to limit access from services and systems.
- Implement a VLAN Access Control List (VACL), a filter that controls access to/from VLANs. VACL filters should be created to deny packets the ability to flow to other VLANs.
- Logically segregate the network using physical or virtual separation allowing network administrators to isolate critical devices onto network segments.
3. Harden Network Devices
A fundamental way to enhance network infrastructure security is to safeguard networking devices with secure configurations. Government agencies, organizations, and vendors supply a wide range of resources to administrators on how to harden network devices. These resources include benchmarks and best practices. These recommendations should be implemented in conjunction with laws, regulations, site security policies, standards, and industry best practices. These guides provide a baseline security configuration for the enterprise that protects the integrity of network infrastructure devices. This guidance supplements the network security best practices supplied by vendors.
- Disable unencrypted remote admin protocols used to manage network infrastructure (e.g., Telnet, FTP).
- Disable unnecessary services (e.g. discovery protocols, source routing, HTTP, SNMP, BOOTP).
- Use SNMPv3 (or subsequent version) but do not use SNMP community strings.
- Secure access to the console, auxiliary, and VTY lines.
- Implement robust password policies and use the strongest password encryption available.
- Protect router/switch by controlling access lists for remote administration.
- Restrict physical access to routers/switches.
- Backup configurations and store offline. Use the latest version of the network device operating system and update with all patches.
- Periodically test security configurations against security requirements.
- Protect configuration files with encryption and/or access controls when sending them electronically and when they are stored and backed up.
4. Secure Access to Infrastructure Devices
Administrative privileges on infrastructure devices allow access to resources that are normally unavailable to most users and permit the execution of actions that would otherwise be restricted. When administrator privileges are improperly authorized, granted widely, and/or not closely audited, intruders can exploit them. These compromised privileges can enable adversaries to traverse a network, expanding access and potentially allowing full control of the infrastructure backbone. Unauthorized infrastructure access can be mitigated by properly implementing secure access policies and procedures.
- Implement Multi-Factor Authentication – Authentication is a process to validate a user’s identity. Weak authentication processes are commonly exploited by attackers. Multi-factor authentication uses at least two identity components to authenticate a user’s identity. Identity components include something the user knows (e.g., password); an object the user has possession of (e.g., token); and a trait unique to the specific person (e.g., biometric).
- Manage Privileged Access – Use an authorization server to store access information for network device management. This type of server will enable network administrators to assign different privilege levels to users based on the principle of least privilege. When a user tries to execute an unauthorized command, it will be rejected. To increase the strength and robustness of user authentication, implement a hard token authentication server in addition to the AAA server, if possible. Multi-factor authentication increases the difficulty for intruders to steal and reuse credentials to gain access to network devices.
- Manage Administrative Credentials – Although multi-factor authentication is highly recommended and a best practice, systems that cannot meet this requirement can at least improve their security level by changing default passwords and enforcing complex password policies. Network accounts must contain complex passwords of at least 14 characters from multiple character domains including lowercase, uppercase, numbers, and special characters. Enforce password expiration and reuse policies. If passwords are stored for emergency access, keep these in a protected off-network location, such as a safe.
5. Perform Out-of-Band Management
Out-of-Band (OoB) management uses alternate communication paths to remotely manage network infrastructure devices. These dedicated paths can vary in configuration to include anything from virtual tunneling to physical separation. Using OoB access to manage the network infrastructure will strengthen security by limiting access and separating user traffic from network management traffic. OoB management provides security monitoring and can implement corrective actions without allowing the adversary who may have already compromised a portion of the network to observe these changes.
OoB management can be implemented physically or virtually, or through a hybrid of the two. Building additional physical network infrastructure is the most secure option for the network managers, although it can be very expensive to implement and maintain. Virtual implementation is less costly, but still requires significant configuration changes and administration. In some situations, such as access to remote locations, virtual encrypted tunnels may be the only viable option.
- Segregate standard network traffic from management traffic.
- Enforce that management traffic on devices only comes from the OoB.
- Apply encryption to all management channels.
- Encrypt all remote access to infrastructure devices such as terminal or dial-in servers.
- Manage all administrative functions from a dedicated host (fully patched) over a secure channel, preferably on the OoB.
- Harden network management devices by testing patches, turning off unnecessary services on routers and switches, and enforcing strong password policies. Monitor the network and review logs Implement access controls that only permit required administrative or management services (SNMP, NTP SSH, FTP, TFTP).
6. Validate Integrity of Hardware and Software
Products purchased through unauthorized channels are often known as “counterfeit,” “secondary,” or “grey market” devices. There have been numerous reports in the press regarding grey market hardware and software being introduced into the marketplace. Grey market products have not been thoroughly tested to meet quality standards and can introduce risks to the network. Lack of awareness or validation of the legitimacy of hardware and software presents a serious risk to users’ information and the overall integrity of the network environment. Products purchased from the secondary market run the risk of having the supply chain breached, which can result in the introduction of counterfeit, stolen, or second-hand devices. This could affect network performance and compromise the confidentiality, integrity, or availability of network assets. Furthermore, breaches in the supply chain provide an opportunity for malicious software or hardware to be installed on the equipment. In addition, unauthorized or malicious software can be loaded onto a device after it is in operational use, so integrity checking of software should be done on a regular basis.
- Maintain strict control of the supply chain; purchase only from authorized resellers.
- Require resellers to implement a supply chain integrity check to validate hardware and software authenticity.
- Inspect the device for signs of tampering.
- Validate serial numbers from multiple sources.
- Download software, updates, patches, and upgrades from validated sources.
- Perform hash verification and compare values against the vendor’s database to detect unauthorized modification to the firmware.
- Monitor and log devices, verifying network configurations of devices on a regular schedule.
- Train network owners, administrators, and procurement personnel to increase awareness of grey market devices.
|Fortinet||CVE-2016-6909||EGREGIOUSBLUNDER||Authentication cookie overflow|
|WatchGuard||CVE-2016-7089||ESCALATEPLOWMAN||Command line injection via ipconfig|
|Cisco||CVE-2016-6366||EXTRABACON||SNMP remote code execution|
|Cisco||CVE-2016-6367||EPICBANANA||Command line injection remote code execution|
|TOPSEC||N/A||ELIGIBLEBACHELOR||Attack vector unknown, but has an XML-like payload|
beginning with <?tos length="001e.%8.8x"?
|TOPSEC||N/A||ELIGIBLEBOMBSHELL||HTTP cookie command injection|
|TOPSEC||N/A||ELIGIBLECANDIDATE||HTTP cookie command injection|
|TOPSEC||N/A||ELIGIBLECONTESTANT||HTTP POST parameter injection|
- Cisco SYNful Knock Security Advisory
- Cisco Security Advisory Multiple Vulnerabilities in Cisco ASA Software
- Cisco Evolution of Attacks on Cisco IOS Devices
- Cisco IOS Software Integrity Assurance
- Information Assurance Advisory NO. IAA U/OO/802097-16 Mitigate Unauthorized Cisco ROMMON
- Information Assurance Advisory NO. IAA U/OO/802488-16 Vulnerabilities in Cisco Adaptive Security Appliances
- Information Assurance Directorate Network Mitigations Package – Infrastructure
- Cisco Guide to Securing Cisco NX-OS Software Devices
- Cisco Guide to Harden Cisco IOS XR Devices
- Cisco Guide to Harden Cisco IOS Devices
- Cisco: A Framework to Protect Data Through Segmentation
- September 6, 2016: Initial release
- September 13, 2016: Added additional references
All Symantec and Norton branded antivirus products
Symantec and Norton branded antivirus products contain multiple vulnerabilities. Some of these products are in widespread use throughout government and industry. Exploitation of these vulnerabilities could allow a remote attacker to take control of an affected system.
The vulnerabilities are listed below:
Symantec Antivirus multiple remote memory corruption unpacking RAR 
- Symantec antivirus products use common unpackers to extract malware binaries when scanning a system. A heap overflow vulnerability in the ASPack unpacker could allow an unauthenticated remote attacker to gain root privileges on Linux or OSX platforms. The vulnerability can be triggered remotely using a malicious file (via email or link) with no user interaction. 
- Symantec: PowerPoint misaligned stream-cache remote stack buffer overflow 
- Symantec: Remote Stack Buffer Overflow in dec2lha library 
- Symantec: Symantec Antivirus multiple remote memory corruption unpacking MSPACK Archives 
- Symantec: Heap overflow modifying MIME messages 
- Symantec: Integer Overflow in TNEF decoder 
- Symantec: missing bounds checks in dec2zip ALPkOldFormatDecompressor::UnShrink 
The large number of products affected (24 products), across multiple platforms (OSX, Windows, and Linux), and the severity of these vulnerabilities (remote code execution at root or SYSTEM privilege) make this a very serious event. A remote, unauthenticated attacker may be able to run arbitrary code at root or SYSTEM privileges by taking advantage of these vulnerabilities. Some of the vulnerabilities require no user interaction and are network-aware, which could result in a wormable-event.
US-CERT encourages users and network administrators to patch Symantec or Norton antivirus products immediately. While there has been no evidence of exploitation, the ease of attack, widespread nature of the products, and severity of the exploit may make this vulnerability a popular target.
-  Symantec Antivirus multiple remote memory corruption unpacking RAR
-  How to Compromise the Enterprise Endpoint
-  Symantec: PowerPoint misaligned stream-cache remote stack buffer overflow
-  Symantec: Remote Stack Buffer Overflow in dec2lha library
-  Symantec: Symantec Antivirus multiple remote memory corruption unpacking MSPACK Archives
-  Symantec: Heap overflow modifying MIME messages
-  Symantec: Integer Overflow in TNEF decoder
-  Symantec: missing bounds checks in dec2zip ALPkOldFormatDecompressor::UnShrink
-  Symantec SYM16-008 security advisory
-  Symantec SYM16-010 security advisory
- July 5, 2016: Initial Release
- Windows, OS X, Linux systems, and web browsers with WPAD enabled
- Networks using unregistered or unreserved TLDs
Web Proxy Auto-Discovery (WPAD) Domain Name System (DNS) queries that are intended for resolution on private or enterprise DNS servers have been observed reaching public DNS servers . In combination with the new generic top level domain (gTLD) program’s incorporation of previously undelegated gTLDs for public registration, leaked WPAD queries could result in domain name collisions with internal network naming schemes  . Opportunistic domain registrants could abuse these collisions by configuring external proxies for network traffic and enabling man-in-the-middle (MitM) attacks across the Internet.
WPAD is a protocol used to ensure all systems in an organization use the same web proxy configuration. Instead of individually modifying configurations on each device connected to a network, WPAD locates a proxy configuration file and applies the configuration automatically.
The use of WPAD is enabled by default on all Microsoft Windows operating systems and Internet Explorer browsers. WPAD is supported but not enabled by default on Mac OS X and Linux-based operating systems, as well as Safari, Chrome, and Firefox browsers.
With the New gTLD program, previously undelegated gTLD strings are now being delegated for public domain name registration . These strings may be used by private or enterprise networks, and in certain circumstances, such as when a work computer is connected from a home or external network, WPAD DNS queries may be made in error to public DNS servers. Attackers may exploit such leaked WPAD queries by registering the leaked domain and setting up MitM proxy configuration files on the Internet.
Other services (e.g., mail and internal web sites) may also perform DNS queries and attempt to automatically connect to supposedly internal DNS names .
Leaked WPAD queries could result in domain name collisions with internal network naming schemes. If an attacker registers a domain to answer leaked WPAD queries and configures a valid proxy, there is potential to conduct man-in-the-middle (MitM) attacks across the Internet.
The WPAD vulnerability is significant to corporate assets such as laptops. In some cases, these assets are vulnerable even while at work, but observations indicate that most assets become vulnerable when used outside an internal network (e.g., home networks, public Wi-Fi networks).
The impact of other types of leaked DNS queries and connection attempts varies depending on the type of service and its configuration.
US-CERT encourages users and network administrators to implement the following recommendations to provide a more secure and efficient network infrastructure:
- Consider disabling automatic proxy discovery/configuration in browsers and operating systems unless those systems will only be used on internal networks.
- Consider using a registered and fully qualified domain name (FQDN) from global DNS as the root for enterprise and other internal namespace.
- Consider using an internal TLD that is under your control and restricted from registration with the new gTLD program. Note that there is no assurance that the current list of “Reserved Names” from the new gTLD Applicant Guidebook (AGB) will remain reserved with subsequent rounds of new gTLDs .
- Configure internal DNS servers to respond authoritatively to internal TLD queries.
- Configure firewalls and proxies to log and block outbound requests for wpad.dat files.
- Identify expected WPAD network traffic and monitor the public namespace or consider registering domains defensively to avoid future name collisions.
- File a report with ICANN if your system is suffering demonstrable severe harm due to name collision by visiting https://forms.icann.org/en/help/name-collision/report-problems.
-  Verisign – MitM Attack by Name Collision: Cause Analysis and Vulnerability Assessment in the New gTLD Era
-  ICANN – Name Collision Resources & Information
-  ICANN – New gTLDs
-  US-CERT – Controlling Outbound DNS Access
-  ICANN – gTLD Applicant Guidebook
- May 23, 2016: Initial Release
- June 1, 2016: Added information on using TLDs restricted from registration with the gTLD program
Outdated or misconfigured SAP systems
At least 36 organizations worldwide are affected by an SAP vulnerability . Security researchers from Onapsis discovered indicators of exploitation against these organizations’ SAP business applications.
The observed indicators relate to the abuse of the Invoker Servlet, a built-in functionality in SAP NetWeaver Application Server Java systems (SAP Java platforms). The Invoker Servlet contains a vulnerability that was patched by SAP in 2010. However, the vulnerability continues to affect outdated and misconfigured SAP systems.
SAP systems running outdated or misconfigured software are exposed to increased risks of malicious attacks.
The Invoker Servlet vulnerability affects business applications running on SAP Java platforms.
SAP Java platforms are the base technology stack for many SAP business applications and technical components, including:
- SAP Enterprise Resource Planning (ERP),
- SAP Product Lifecycle Management (PLM),
- SAP Customer Relationship Management (CRM),
- SAP Supply Chain Management (SCM),
- SAP Supplier Relationship Management (SRM),
- SAP NetWeaver Business Warehouse (BW),
- SAP Business Intelligence (BI),
- SAP NetWeaver Mobile Infrastructure (MI),
- SAP Enterprise Portal (EP),
- SAP Process Integration (PI),
- SAP Exchange Infrastructure (XI),
- SAP Solution Manager (SolMan),
- SAP NetWeaver Development Infrastructure (NWDI),
- SAP Central Process Scheduling (CPS),
- SAP NetWeaver Composition Environment (CE),
- SAP NetWeaver Enterprise Search,
- SAP NetWeaver Identity Management (IdM), and
- SAP Governance, Risk & Control 5.x (GRC).
The vulnerability resides on the SAP application layer, so it is independent of the operating system and database application that support the SAP system.
Exploitation of the Invoker Servlet vulnerability gives unauthenticated remote attackers full access to affected SAP platforms, providing complete control of the business information and processes on these systems, as well as potential access to other systems.
In order to mitigate this vulnerability, US-CERT recommends users and administrators implement SAP Security Note 1445998 and disable the Invoker Servlet. For more mitigation details, please review the Onapsis threat report .
In addition, US-CERT encourages that users and administrators:
- Scan systems for all known vulnerabilities, such as missing security patches and dangerous system configurations.
- Identify and analyze the security settings of SAP interfaces between systems and applications to understand risks posed by these trust relationships.
- Analyze systems for malicious or excessive user authorizations.
- Monitor systems for indicators of compromise resulting from the exploitation of vulnerabilities.
- Monitor systems for suspicious user behavior, including both privileged and non-privileged users.
- Apply threat intelligence on new vulnerabilities to improve the security posture against advanced targeted attacks.
- Define comprehensive security baselines for systems and continuously monitor for compliance violations and remediate detected deviations.
These recommendations apply to SAP systems in public, private, and hybrid cloud environments.
Note: The U.S. Government does not endorse or support any particular product or vendor.
-  Onapsis Threat Report: Wild Exploitation & Cyber-Attacks on SAP Business Applications
-  SAP: Invoker Servlet
- May 11, 2016: Initial Release
Microsoft Windows with Apple QuickTime installed
According to Trend Micro, Apple will no longer be providing security updates for QuickTime for Windows, leaving this software vulnerable to exploitation. 
All software products have a lifecycle. Apple will no longer be providing security updates for QuickTime for Windows. 
Computer systems running unsupported software are exposed to elevated cybersecurity dangers, such as increased risks of malicious attacks or electronic data loss. Exploitation of QuickTime for Windows vulnerabilities could allow remote attackers to take control of affected systems.
Computers running QuickTime for Windows will continue to work after support ends. However, using unsupported software may increase the risks from viruses and other security threats. Potential negative consequences include loss of confidentiality, integrity, or availability of data, as well as damage to system resources or business assets. The only mitigation available is to uninstall QuickTime for Windows. Users can find instructions for uninstalling QuickTime for Windows on the Apple Uninstall QuickTime page. 
-  Trend Micro - Urgent Call to Action: Uninstall QuickTime for Windows Today
-  Zero Day Initiative Advisory ZDI 16-241: (0Day) Apple QuickTime moov Atom Heap Corruption Remote Code Execution Vulnerabilit
-  Zero Day Initiative Advisory ZDI 16-242: (0Day) Apple QuickTime Atom Processing Heap Corruption Remote Code Execution Vulner
-  Apple - Uninstall QuickTime 7 for Windows
- April 14, 2016: Initial Release
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