Sofacy Group Malware Sample 2

Hunt Hypothesis

Sofacy Group is deploying a custom malware sample to establish persistence and exfiltrate data within the network. SOC teams should proactively hunt for this behavior in Azure Sentinel to detect and mitigate Sofacy Group’s advanced persistent threat operations before significant data loss occurs.

YARA Rule

rule Sofacy_Bundestag_Mal2 
{

    meta:
        description = "Sofacy Group Malware Sample 2"
        author = "Florian Roth"
        reference = "http://dokumente.linksfraktion.de/inhalt/report-orig.pdf"
        date = "2015-06-19"
        hash = "566ab945f61be016bfd9e83cc1b64f783b9b8deb891e6d504d3442bc8281b092"
        score = 70
   
    strings:
        $x1 = "PROJECT\\XAPS_OBJECTIVE_DLL\\" ascii
        $x2 = "XAPS_OBJECTIVE.dll" fullword ascii
        $s1 = "i`m wait" fullword ascii 
   
    condition:
        uint16(0) == 0x5a4d and ( 1 of ($x*) ) and $s1
}

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 3 string patterns in its detection logic.

References

False Positive Guidance

Scenario: Legitimate system update or patching process using Windows Update or WSUS
Filter/Exclusion: Check for ProcessName = "wuauclt.exe" or ProcessName = "wusa.exe" and exclude based on known update processes.
Scenario: Scheduled backup job using Veeam Backup & Replication or Commvault
Filter/Exclusion: Filter by ProcessName = "veeam.exe" or ProcessName = "cvbackup.exe" and exclude based on known backup tasks.
Scenario: Administrative task involving PowerShell script execution for system maintenance
Filter/Exclusion: Filter by ProcessName = "powershell.exe" and check for known administrative scripts or use CommandLine to exclude benign PowerShell commands.
Scenario: Use of Microsoft Defender ATP for malware scanning or threat hunting
Filter/Exclusion: Filter by ProcessName = "MsMpEng.exe" or ProcessName = "MSPaint.exe" (for Defender UI) and exclude based on known security tool processes.
Scenario: Legitimate use of Sysinternals tools like Process Explorer or Procmon for troubleshooting
Filter/Exclusion: Filter by ProcessName = "procmon.exe" or ProcessName = "process.explorer.exe" and exclude based on known Sysinternals usage.