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APT malware used to drop PcClient RAT

yara LOW Yara-Rules
aptbackdoorcommunity
This rule was pulled from an open-source repository and enriched with AI. Validate in a test environment before deploying to production.
View original rule at Yara-Rules →
Retrieved: 2026-05-19T23:00:00Z · Confidence: medium

Hunt Hypothesis

The detection identifies potential APT malware activity where an adversary may be dropping the PcClient RAT to establish persistent remote access. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify early-stage compromise and prevent lateral movement and data exfiltration.

YARA Rule

rule apt_c16_win64_dropper
{

    meta:
        author = "@dragonthreatlab"
        date = "2015/01/11"
        description = "APT malware used to drop PcClient RAT"
        reference = "http://blog.dragonthreatlabs.com/2015/01/dtl-12012015-01-hong-kong-swc-attack.html"

    strings:
        $mz = { 4D 5A }
        $str1 = "clbcaiq.dll" ascii
        $str2 = "profapi_104" ascii
        $str3 = "\\Microsoft\\wuauclt\\wuauclt.dat" ascii
        $str4 = { 0F B6 0A 48 FF C2 80 E9 03 80 F1 03 49 FF C8 88 4A FF 75 EC }

    condition:
        $mz at 0 and all of ($str*)
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

This rule contains 5 string patterns in its detection logic.

References

False Positive Guidance

Original source: https://github.com/Yara-Rules/rules/blob/main/malware/APT_C16.yar