md5 2495b460f28f45b40d92da406be15627

Hunt Hypothesis

The hypothesis is that the detected MD5 hash corresponds to a potentially malicious file used by an adversary for initial compromise or persistence. A SOC team 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_2495b460f28f45b40d92da406be15627 {
    strings: $ = "$dez = $pwddir.\"/\".$real;copy($uploaded, $dez);"
    condition: any of them
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 1 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: Legitimate system backup using Veeam Backup & Replication
  Filter/Exclusion: Check for known Veeam backup directories (e.g., C:\ProgramData\Veeam\Backup) and exclude files with known Veeam backup file extensions (e.g., .vbk, .vib, .vlog).

• Scenario: Scheduled system integrity check using Microsoft System File Checker (SFC)
  Filter/Exclusion: Exclude files in the C:\Windows\System32 directory and filter out processes associated with sfc.exe or dism.exe.

• Scenario: Regular log file rotation using LogParser or Windows Event Log Management Tools
  Filter/Exclusion: Exclude files in the C:\Windows\System32\LogFiles directory and filter out processes related to log management tools like LogParser or Event Viewer.

• Scenario: Antivirus signature update using Microsoft Defender ATP
  Filter/Exclusion: Exclude files in the C:\ProgramData\Microsoft\Windows Defender\Scans directory and filter out processes associated with MsDefenderATP.exe or MpCmdRun.exe.

• Scenario: Automated patch deployment using Microsoft Endpoint Configuration Manager (MEMCM)
  Filter/Exclusion: Exclude files in the C:\Windows\Temp directory and filter out processes related to ConfigMgr or Software Distribution services.