SuckStopv111

Hunt Hypothesis

This rule detects the presence of the SuckStopv111 malware signature, which is often associated with low-severity web-based exploits or adware that may serve as an initial foothold for further compromise. Proactively hunting for this indicator allows the SOC team to identify potentially vulnerable endpoints or user sessions before the malware can escalate privileges or establish persistent connections within the Azure environment.

YARA Rule

rule SuckStopv111
{
      meta:
		author="malware-lu"
strings:
		$a0 = { EB [3] BE [2] B4 30 CD 21 EB ?? 9B }

condition:
		$a0 at pe.entry_point
}

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 1 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: The SuckStopv111 YARA rule likely targets specific memory patterns or string signatures associated with a known malware family or exploit kit (e.g., a specific version of a wiper or infostealer). In a legitimate environment, this could be triggered by memory dumps from debugging sessions using tools like WinDbg or x64dbg where an analyst is analyzing a benign application that coincidentally contains the same byte sequence or string pattern targeted by the rule.

  • Filter/Exclusion: Exclude alerts where the process name is windbg.exe, x64dbg.exe, or dbgview.exe and the parent process is a development or testing IDE (e.g., devenv.exe, code.exe).

• Scenario: The rule may detect a specific scheduled task or service that uses a known library or binary component (e.g., a specific version of libcurl or a proprietary agent) that has a static signature matching the YARA pattern. For instance, Microsoft Defender for Endpoint or CrowdStrike Falcon agents might update their core binaries, and if the new version contains a string or code block that matches the SuckStopv111 signature, it could trigger a false positive during the update process.

  • Filter/Exclusion: Exclude alerts where the process path resides in standard security agent directories (e.g., C:\Program Files\Microsoft Security Client\, C:\Program Files\CrowdStrike\) and the action is Update or Install.

• Scenario: Virtual Machine snapshots or backups using tools like Veeam Backup & Replication or Commvault may create temporary files or memory maps that contain the specific byte sequence targeted by the rule. If the backup software restores or processes a file that was previously