Wild Neutron APT Sample Rule - file c2c761cde3175f6e40ed934f2e82c76602c81e2128187bab61793ddb3bc686d0

Hunt Hypothesis

The detection identifies potential command and control activity associated with the Wild Neutron APT group, leveraging a specific file hash to indicate malicious network communication. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage APT operations before they escalate to data exfiltration or system compromise.

YARA Rule

rule WildNeutron_Sample_3 
{

    meta:
        description = "Wild Neutron APT Sample Rule - file c2c761cde3175f6e40ed934f2e82c76602c81e2128187bab61793ddb3bc686d0"
        author = "Florian Roth"
        reference = "https://securelist.com/blog/research/71275/wild-neutron-economic-espionage-threat-actor-returns-with-new-tricks/"
        date = "2015-07-10"
        score = 60
        hash = "c2c761cde3175f6e40ed934f2e82c76602c81e2128187bab61793ddb3bc686d0"
   
    strings:
        $x1 = "178.162.197.9" fullword ascii /* score: '9.00' */
        $x2 = "\"http://fw.ddosprotected.eu:80 /opts resolv=drfx.chickenkiller.com\"" fullword wide /* PEStudio Blacklist: strings */ /* score: '33.00' */
        $s1 = "LiveUpdater.exe" fullword wide /* PEStudio Blacklist: strings */ /* score: '25.00' */
        $s2 = "id-at-postalAddress" fullword ascii /* PEStudio Blacklist: strings */ /* score: '18.00' */
        $s3 = "%d -> %d (default)" fullword wide /* PEStudio Blacklist: strings */ /* score: '17.00' */
        $s4 = "%s%s%s=%d,%s=%d,%s=%d," fullword wide /* score: '15.00' */
        $s5 = "id-at-serialNumber" fullword ascii /* PEStudio Blacklist: strings */ /* score: '10.00' */
        $s6 = "ECDSA with SHA256" fullword ascii /* PEStudio Blacklist: strings */ /* score: '10.00' */
        $s7 = "Acer LiveUpdater" fullword wide /* PEStudio Blacklist: strings */ /* score: '10.00' */
    
    condition:
        uint16(0) == 0x5a4d and filesize < 2020KB and ( 1 of ($x*) or all of ($s*) )
}

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 9 string patterns in its detection logic.

References

• https://securelist.com/blog/research/71275/wild-neutron-economic-espionage-threat-actor-returns-with-new-tricks/
• Source Rule

False Positive Guidance

• Scenario: Legitimate System Update via Windows Update
  Description: A file with the hash c2c761cde3175f6e40ed934f2e82c76602c81e2128187bab61793ddb3bc686d0 is detected during a Windows Update process.
  Filter/Exclusion: process.name = "wuauclt.exe" or process.parent.name = "svchost.exe"

• Scenario: Scheduled Job for Log File Analysis
  Description: A scheduled task runs a script that processes log files, and the file with the given hash is used as part of log analysis tools like logparser.exe.
  Filter/Exclusion: process.name = "logparser.exe" or process.parent.name = "schtasks.exe"

• Scenario: Admin Task for Configuration Backup
  Description: An administrator uses a tool like wbadmin.exe to perform a system configuration backup, and the file is part of the backup process.
  Filter/Exclusion: process.name = "wbadmin.exe" or process.parent.name = "explorer.exe"

• Scenario: Antivirus Quarantine File
  Description: A file with the hash is moved to quarantine by an endpoint protection solution like Microsoft Defender, which temporarily stores such files.
  Filter/Exclusion: process.name = "MsMpEng.exe" or process.name = "Windows Defender Antivirus" and file.quarantined = true

• Scenario: Legitimate Software Distribution via Microsoft Intune
  Description: A file with the hash is deployed via Microsoft Intune as part of a legitimate software update or configuration management task.
  Filter/Exclusion: `process.name = ”