Wild Neutron APT Sample Rule - file 8d80f9ef55324212759f4b6070cb8fce18a008ae9dd8b9598553206654d13a6f

Hunt Hypothesis

The detection identifies potential Wild Neutron APT activity through suspicious file behavior indicative of adversary persistence and lateral movement. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate advanced persistent threats before they escalate.

YARA Rule

rule WildNeutron_Sample_2 
{

    meta:
        description = "Wild Neutron APT Sample Rule - file 8d80f9ef55324212759f4b6070cb8fce18a008ae9dd8b9598553206654d13a6f"
        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 = "8d80f9ef55324212759f4b6070cb8fce18a008ae9dd8b9598553206654d13a6f"

    strings:
        $s0 = "rundll32.exe \"%s\",#1" fullword wide /* PEStudio Blacklist: strings */ /* score: '33.00' */
        $s1 = "IgfxUpt.exe" fullword wide /* score: '20.00' */
        $s2 = "id-at-postalAddress" fullword ascii /* PEStudio Blacklist: strings */ /* score: '18.00' */
        $s3 = "Intel(R) Common User Interface" fullword wide /* PEStudio Blacklist: strings */ /* score: '17.00' */
        $s4 = "%s%s%s=%d,%s=%d,%s=%d," fullword wide /* score: '15.00' */
        $s11 = "Key Usage" fullword ascii /* score: '12.00' */
        $s12 = "Intel Integrated Graphics Updater" fullword wide /* PEStudio Blacklist: strings */ /* score: '12.00' */
        $s13 = "%sexpires on    : %04d-%02d-%02d %02d:%02d:%02d" fullword ascii /* PEStudio Blacklist: strings */ /* score: '11.00' */

    condition:
        uint16(0) == 0x5a4d and filesize < 600KB and all 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 8 string patterns in its detection logic.

References

False Positive Guidance

Scenario: Legitimate System Update via Windows Update
Description: A file with a similar hash to the malicious sample is part of a legitimate Windows update or system patch.
Filter/Exclusion: Check the file path against known Windows update directories (e.g., C:\Windows\Temp, C:\Windows\SoftwareDistribution). Use a filter like:
```
file.path != "C:\Windows\*" and file.path != "C:\Program Files\*"
```
Scenario: Scheduled Job for Log Collection
Description: A scheduled task is running a script that generates a file with a hash matching the malicious sample, used for log collection or monitoring.
Filter/Exclusion: Check the process name and user context. Use a filter like:
```
process.name != "logcollector.exe" and process.name != "syslogd.exe"
```
Scenario: Admin Task for File Integrity Monitoring (FIM)
Description: An admin is using a tool like Tripwire or OSSEC to generate a file for integrity checks, which may have a similar hash.
Filter/Exclusion: Check the process name and file path. Use a filter like:
```
process.name != "tripwire" and process.name != "ossec" and file.path != "C:\Program Files\Tripwire\*"
```
Scenario: Legitimate Software Installation
Description: A legitimate software package (e.g., VMware Tools, Microsoft Office, or Adobe Acrobat) is being installed, and the installer generates a file with a similar hash.
Filter/Exclusion: Check the file name and process name. Use a filter like:
```
file.name != "vmtoolsd.exe" and file.name != "
```