Used to detect MalumPOS memory dumper

Hunt Hypothesis

This hypothesis posits that adversaries are deploying MalumPOS memory dumpers to extract sensitive credentials and cryptographic keys from volatile system memory in Azure environments. The SOC team should proactively hunt for this behavior because early detection of these specific dumper activities can prevent lateral movement and data exfiltration before the malware establishes persistence or escalates privileges.

YARA Rule

rule PoS_Malware_MalumPOS
{
    meta:
        author = "Trend Micro, Inc."
        date = "2015-05-25"
        description = "Used to detect MalumPOS memory dumper"
        sample_filtype = "exe"
    strings:
        $string1 = "SOFTWARE\\Borland\\Delphi\\RTL"
        $string2 = "B)[0-9]{13,19}\\"
        $string3 = "[A-Za-z\\s]{0,30}\\/[A-Za-z\\s]{0,30}\\"
        $string4 = "TRegExpr(exec): ExecNext Without Exec[Pos]"
        $string5 = /Y:\\PROGRAMS\\.{20,300}\.pas/ 
    condition:
        all of ($string*)
}

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 5 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the MalumPOS Memory Dumper detection rule, along with suggested filters or exclusions:

• Automated Endpoint Backup via Veeam Agent

  • Scenario: The Veeam Agent service (running as veeamagent.exe) initiates a scheduled backup job that includes memory state snapshots of critical POS terminals. This process involves reading large contiguous blocks of memory, mimicking the behavior of a memory dumper tool.
  • Filter/Exclusion: Exclude processes with the executable path containing \Veeam\EndpointBackup\ and the parent process svchost.exe or services.exe. Additionally, filter out events where the command line arguments contain -snapshot or -memory flags during standard business hours (08:00–17:00).

• Microsoft Windows Update Troubleshooting Diagnostics

  • Scenario: During a major OS update cycle, the WindowsUpdateTray.exe or DismHost.exe triggers a diagnostic routine to capture memory dumps for failed installation components. This is often triggered by the “Problem Reports and Solutions” scheduled task (Microsoft\Windows\Diagnosis).
  • Filter/Exclusion: Create an exclusion rule for processes owned by the NT AUTHORITY\SYSTEM account where the executable name matches DismHost.exe, WerFault.exe, or MsMpEng.exe. Specifically, filter events originating from the scheduled task path \Microsoft\Windows\Diagnosis with a duration under 15 minutes.

• Salesforce POS Terminal Health Check (SAP/Oracle Integration)

  • Scenario: Enterprise POS terminals running SAP or Oracle middleware execute a nightly health check script (pos_health_check.ps1) that invokes dumpbin.exe to analyze the memory footprint of the transaction engine before closing the day’s ledger