This detection rule identifies the execution of the Ponmocup Installer, a legitimate software component that adversaries may leverage to establish persistence or mask malicious activity within Azure Sentinel environments. Proactively hunting for this behavior is essential because its low severity classification often leads to alert fatigue, allowing threat actors to exploit it as a trusted foothold before initiating more aggressive attack phases.
rule Trj_Ponmocup {
meta:
author = "Centro Criptológico Nacional (CCN)"
ref ="https://www.ccn-cert.cni.es/informes/informes-ccn-cert-publicos.html"
description = "Ponmocup Installer"
strings:
$mz = { 4d 5a }
$pac = { 48 8F BB 54 5F 3E 4F 4E }
$unp = { 8B B8 7C 1F 46 00 33 C8 }
condition:
($mz at 0) and ($pac at 0x61F7C) and ($unp at 0x29F0)
}
This YARA rule can be deployed in the following contexts:
This rule contains 3 string patterns in its detection logic.
Here are 5 specific false positive scenarios for the Ponmocup Installer detection rule in an enterprise environment, along with suggested filters or exclusions:
Scheduled Patch Management Deployment
Parent_Process_Name matches known deployment agents (e.g., ccmexec.exe, jamfagentd) and the execution time falls within the defined maintenance window (e.g., 02:00–04:00 UTC).Onboarding Automation Script Execution
New-UserSetup.ps) running under the SYSTEM or Domain Admin account to provision new laptops. As part of the standard image build, this script invokes the Ponmocup Installer to deploy essential security and productivity suites before handing the device to the end-user.svc-onboarding) or where the User_Name is a known administrative identity, specifically when the command line arguments contain flags like /silent, /norestart, or /deploy.Third-Party Endpoint Protection Integration