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OrcaRAT

yara LOW Yara-Rules
backdoorcommunity
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: 2026-06-26T11:00:00Z · Confidence: medium

Hunt Hypothesis

The OrcaRAT detection rule identifies potential command and control communication associated with the OrcaRAT malware, which may indicate an adversary establishing persistent remote access. SOC teams should proactively hunt for this behavior in Azure Sentinel to detect and respond to early-stage compromise attempts by advanced persistent threats.

YARA Rule

rule OrcaRAT
{
    meta:
        Author      = "PwC Cyber Threat Operations"
        Date        = "2014/10/20" 
        Description = "Strings inside"
        Reference   = "http://pwc.blogs.com/cyber_security_updates/2014/10/orcarat-a-whale-of-a-tale.html"

    strings:
        $MZ = "MZ"
        $apptype1 = "application/x-ms-application"
        $apptype2 = "application/x-ms-xbap"
        $apptype3 = "application/vnd.ms-xpsdocument"
        $apptype4 = "application/xaml+xml"
        $apptype5 = "application/x-shockwave-flash"
        $apptype6 = "image/pjpeg"
        $err1 = "Set return time error =   %d!"
        $err2 = "Set return time   success!"
        $err3 = "Quit success!"

    condition:
        $MZ at 0 and filesize < 500KB and (all of ($apptype*) and 1 of ($err*))
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

This rule contains 10 string patterns in its detection logic.

False Positive Guidance

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