Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
17 detections
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Detects the execution of PowerShell scripts that utilize a multi-stage deobfuscation and loading technique. The script decrypts a staged payload using AesManaged (with specific hardcoded byte constants), decompresses the result via GZipStream, and uses [System.Reflection.Assembly]::Load to reflectively execute the resulting .NET assembly in memory. This pattern is characteristic of advanced malware loader chains, such as those used by the 'LausivLoader'.
Detects emails containing a RAR attachment combined with a shortened URL. This combination is a common technique used in phishing campaigns to deliver malicious payloads while attempting to evade security filters.
This rule detects suspicious activity involving a high volume of file compression using common archiving tools like 7-Zip and WinRAR. Adversaries often compress data before exfiltration or for staging purposes to reduce size and potentially evade detection. A high count of compression events within a short timeframe (1 hour) by a single account could indicate malicious activity.
Detects potential exploitation of 7-Zip RAR5 vulnerabilities where the Mark-of-the-Web (MOTW) Zone.Identifier is not propagated during extraction, enabling files to execute without SmartScreen warnings. The rule monitors for the creation of executable file types in common user-writable directories by 7-Zip processes and the subsequent execution of files from those locations by explorer.exe.
Detects the use of 7za to extract archives into the Avast Software directory, a behavior observed in Pay2Key ransomware campaigns to perform DLL hijacking for execution, persistence, or privilege escalation.
This rule detects the execution of self-extracting archives (SFX) that are commonly used by malware to launch a visible decoy and a hidden executable from a temporary directory. It specifically looks for process launch events where the command line contains keywords associated with SFX archives (e.g., '7-zip', 'sfx', '-y', '-o') and the principal process's file path contains terms like '7z', 'sfx', 'setup', or 'installer'. The rule aims to identify the initial stage of an attack where an SFX archive is used to drop and execute malicious payloads.
This rule detects suspicious activity involving a high volume of file compression using common archiving tools like 7-Zip and WinRAR. Adversaries often compress data before exfiltration or for staging purposes to reduce size and potentially evade detection. A high count of compression events within a short timeframe (1 hour) by a single account could indicate malicious activity.
This rule detects the execution of self-extracting (SFX) archives that launch both a visible decoy and a hidden second executable from the temporary directory. It specifically looks for process command lines containing patterns indicative of 7-zip or generic SFX archive execution, combined with an actor process image name suggesting an archive utility or installer. The rule aims to identify malicious SFX archives used in multi-stage attacks, providing causality fields for investigation.
This rule detects the execution of self-extracting archives (SFX) that are commonly used by malware to launch a visible decoy and a hidden executable from a temporary directory. It specifically looks for process launch events where the command line contains keywords associated with SFX archives (e.g., '7-zip', 'sfx', '-y', '-o') and the principal process's file path contains terms like '7z', 'sfx', 'setup', or 'installer'. The rule aims to identify the initial stage of an attack where an SFX archive is used to drop and execute malicious payloads.
This rule detects the download of a compressed executable payload over HTTP. It specifically looks for HTTP traffic flowing to the client that contains both the GZIP magic number (1F 8B) and the Windows executable magic number (MZ) within the file data. This combination suggests a compressed executable file being delivered, which is a common technique used by malware to evade detection.
Detects command line executions using the 7z compression utility to extract archives with a specific hardcoded password (-pppp). This behavior is an established staging artifact observed in ClickFix campaigns (such as the QuickBooks and Booking.com clusters) to deploy payloads like the NetSupport RAT.
Detects a web server process spawning tools commonly used for data staging and exfiltration, such as rar.exe, certutil.exe, and type.exe. This behavior is characteristic of the CL-UNK-1068 actor's exfiltration TTP, often performed via a web shell.
KQL Query
One common technique leveraged by attackers is using archiving applications to package up files for exfiltration. In many cases, these archives are usually protected with a password to make analysis more difficult. This query identifies applications which leverage a command line pattern which matches the 7zip and WinRAR command line executables to create or update an archive when a password is specified. By detecting based on the command line we can avert attempts to dodge detection by renaming the application.
Happy hunting!
Happy hunting!
These queries was originally published in the threat analytics report, Attacks on gov't, think tanks, NGOs.
As described further in Analysis of cyberattack on U.S. think tanks, non-profits, public sector by unidentified attackers, there was a very large spear-phishing campaign launched in November 2019.
The attackers would gain access to a target by having the user click on a link to a compromised website and download a .zip archive.
Once established on a target's device, the attackers used a malicious DLL named cyzfc.dat to execute additional payloads. They would call a function in the malicious DLL via the legitimate Windows process, rundll32.exe, to connect directly to their command-and-control (C2) servers.
The following queries detect activity associated with the malicious DLL, cyzfc.dat., used in this campaign.
Reference - https://docs.microsoft.com/windows-server/administration/windows-commands/rundll32
As described further in Analysis of cyberattack on U.S. think tanks, non-profits, public sector by unidentified attackers, there was a very large spear-phishing campaign launched in November 2019.
The attackers would gain access to a target by having the user click on a link to a compromised website and download a .zip archive.
Once established on a target's device, the attackers used a malicious DLL named cyzfc.dat to execute additional payloads. They would call a function in the malicious DLL via the legitimate Windows process, rundll32.exe, to connect directly to their command-and-control (C2) servers.
The following queries detect activity associated with the malicious DLL, cyzfc.dat., used in this campaign.
Reference - https://docs.microsoft.com/windows-server/administration/windows-commands/rundll32
This rule detects the execution of common archiving utilities (zip, gzip, tar) on Linux systems. Adversaries often compress data prior to exfiltration to reduce its size and make it easier to transfer. This rule specifically looks for the 'execve' system call with 'zip', 'gzip -k', or 'tar -c' as the primary command and arguments.
Detects attempts of decoding a base64 Gzip archive via PowerShell. This technique is often used as a method to load malicious content into memory afterward. The detection relies on the presence of 'FromBase64String' for decoding, 'MemoryStream' for in-memory operations, and 'H4sI' which is a common magic string for Gzip compressed data.