Wild Neutron APT Sample Rule - file 1d3bdabb350ba5a821849893dabe5d6056bf7ba1ed6042d93174ceeaa5d6dad7

Hunt Hypothesis

The detection identifies potential Wild Neutron APT activity through the presence of a suspicious file associated with known malicious campaigns. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate advanced persistent threats before they cause significant damage.

YARA Rule

rule WildNeutron_Sample_10 
{

    meta:
        description = "Wild Neutron APT Sample Rule - file 1d3bdabb350ba5a821849893dabe5d6056bf7ba1ed6042d93174ceeaa5d6dad7"
        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 = "1d3bdabb350ba5a821849893dabe5d6056bf7ba1ed6042d93174ceeaa5d6dad7"

    strings:
        $n1 = "/c for /L %%i in (1,1,2) DO ping 127.0.0.1 -n 3 & type %%windir%%\\notepad.exe > %s & del /f %s" fullword ascii /* PEStudio Blacklist: strings */ /* score: '46.00' */        
        $s1 = "%SYSTEMROOT%\\temp\\_dbg.tmp" fullword ascii /* PEStudio Blacklist: strings */ /* score: '37.00' */
        $s2 = "%SYSTEMROOT%\\SysWOW64\\mspool.dll" fullword ascii /* PEStudio Blacklist: strings */ /* score: '36.17' */
        $s3 = "%SYSTEMROOT%\\System32\\dpcore16t.dll" fullword ascii /* PEStudio Blacklist: strings */ /* score: '36.17' */
        $s4 = "%SYSTEMROOT%\\System32\\wdigestEx.dll" fullword ascii /* PEStudio Blacklist: strings */ /* score: '36.17' */
        $s5 = "%SYSTEMROOT%\\System32\\mspool.dll" fullword ascii /* PEStudio Blacklist: strings */ /* score: '36.17' */
        $s6 = "%SYSTEMROOT%\\System32\\kernel32.dll" fullword ascii /* PEStudio Blacklist: strings */ /* score: '36.00' */
        $s7 = "%SYSTEMROOT%\\SysWOW64\\iastor32.exe" fullword ascii /* PEStudio Blacklist: strings */ /* score: '31.17' */
        $s8 = "%SYSTEMROOT%\\System32\\msvcse.exe" fullword ascii /* PEStudio Blacklist: strings */ /* score: '31.17' */
        $s9 = "%SYSTEMROOT%\\System32\\mshtaex.exe" fullword ascii /* PEStudio Blacklist: strings */ /* score: '31.17' */
        $s10 = "%SYSTEMROOT%\\System32\\iastor32.exe" fullword ascii /* PEStudio Blacklist: strings */ /* score: '31.17' */
        $s11 = "%SYSTEMROOT%\\SysWOW64\\mshtaex.exe" fullword ascii /* PEStudio Blacklist: strings */ /* score: '31.17' */
        $x1 = "wdigestEx.dll" fullword ascii /* PEStudio Blacklist: strings */ /* score: '26.00' */
        $x2 = "dpcore16t.dll" fullword ascii /* score: '21.00' */
        $x3 = "mspool.dll" fullword ascii /* score: '21.00' */
        $x4 = "msvcse.exe" fullword ascii /* score: '20.00' */
        $x5 = "mshtaex.exe" fullword wide /* score: '20.00' */
        $x6 = "iastor32.exe" fullword ascii /* score: '20.00' */
        $y1 = "Installer.exe" fullword ascii /* PEStudio Blacklist: strings */ /* score: '25.00' */
        $y2 = "Info: Process %s" fullword ascii /* PEStudio Blacklist: strings */ /* score: '21.00' */
        $y3 = "Error: GetFileTime %s 0x%x" fullword ascii /* score: '17.00' */
        $y4 = "Install succeeded" fullword ascii /* PEStudio Blacklist: strings */ /* score: '10.00' */
        $y5 = "Error: RegSetValueExA 0x%x" fullword ascii /* score: '9.00' */
   
    condition:
        uint16(0) == 0x5a4d and filesize < 400KB and ( $n1 or ( 1 of ($s*) and 1 of ($x*) and 3 of ($y*)))
}

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 23 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: System Update via Windows Update
  Description: A legitimate Windows update process may trigger the rule due to the presence of a file with a similar hash.
  Filter/Exclusion: file.name != "WindowsUpdate.exe" or process.name != "wuauclt.exe"

• Scenario: Scheduled Backup Job Using Veeam Backup & Replication
  Description: Veeam may generate files with hashes resembling malicious samples during backup operations.
  Filter/Exclusion: process.name != "VeeamBackup.exe" or file.name != "VeeamBackup*.exe"

• Scenario: Admin Task Using PowerShell for System Configuration
  Description: PowerShell scripts run by administrators for system configuration (e.g., Invoke-Command, Set-ItemProperty) may trigger the rule.
  Filter/Exclusion: process.name != "powershell.exe" or user.name != "Administrator"

• Scenario: Log File Parsing with Splunk
  Description: Splunk may generate temporary files or use scripts that match the rule’s hash during log parsing or indexing.
  Filter/Exclusion: process.name != "splunkd.exe" or file.name != "splunk*"

• Scenario: Antivirus Quarantine File Handling
  Description: Antivirus tools like Bitdefender or Kaspersky may temporarily store quarantined files with hashes similar to the rule’s.
  Filter/Exclusion: process.name != "bitdefender*" or file.name != "quarantine*"