The detection rule identifies potential malicious activity associated with a specific MD5 hash, indicating possible exploitation of a known or unknown threat. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage threats that may evade traditional detection methods.
YARA Rule
rule md5_2c37d90dd2c9c743c273cb955dd83ef6 {
strings: $ = "@$_($_REQUEST['"
condition: any of them
}
This YARA rule can be deployed in the following contexts:
Scenario: A system administrator is using PowerShell to generate a hash for a known good file as part of a compliance check.
Filter/Exclusion: Exclude processes where the command line contains Get-FileHash or certutil -hashfile.
Scenario: A scheduled backup job is running and temporarily creates a file with the same MD5 hash due to a temporary file or log file.
Filter/Exclusion: Exclude processes associated with backup tools like Veeam, Commvault, or Veritas NetBackup.
Scenario: A software update is being deployed using Chocolatey or WSUS, and the update package temporarily matches the MD5 hash.
Filter/Exclusion: Exclude processes related to package managers like choco.exe or wsusutil.exe.
Scenario: A system integrity check is being performed using Sysinternals tools like Process Explorer or Autoruns, which may generate temporary files with matching hashes.
Filter/Exclusion: Exclude processes from the Sysinternals suite or known system diagnostic tools.
Scenario: A log file is being rotated or archived by Logstash or ELK stack, and the file temporarily matches the MD5 hash due to naming conventions.
Filter/Exclusion: Exclude processes related to log management tools like logstash.exe, kibana, or filebeat.