Disclosed hacktool set (old stuff) - file 2323.exe

Hunt Hypothesis

This detection identifies adversaries deploying legacy or unverified hacking tools, such as the observed file 2323.exe, which often serve as initial footholds for reconnaissance and lateral movement within an Azure Sentinel environment. Proactively hunting for these disclosed artifacts is critical to uncover dormant threats that may have evaded automated signatures due to their age or lack of comprehensive MITRE mapping, thereby reducing the window for potential compromise.

YARA Rule

rule sig_238_2323 {
	meta:
		description = "Disclosed hacktool set (old stuff) - file 2323.exe"
		author = "Florian Roth"
		date = "23.11.14"
		score = 60
		hash = "21812186a9e92ee7ddc6e91e4ec42991f0143763"
	strings:
		$s0 = "port - Port to listen on, defaults to 2323" fullword ascii
		$s1 = "Usage: srvcmd.exe [/h] [port]" fullword ascii
		$s3 = "Failed to execute shell" fullword ascii
		$s5 = "/h   - Hide Window" fullword ascii
		$s7 = "Accepted connection from client at %s" fullword ascii
		$s9 = "Error %d: %s" fullword ascii
	condition:
		all of them
}

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 6 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the detection rule Disclosed hacktool set (old stuff) - file 2323.exe, along with recommended filters and exclusions:

• Legacy Patch Management Deployment

  • Scenario: The enterprise uses an older version of a patch management suite (e.g., Microsoft SCCM/ConfigMgr or Ivanti Neurons) that extracts a temporary installer named 2323.exe during the “Application Installation” phase on endpoint agents. This file is often signed by the vendor but flagged as “old stuff” due to its generic naming convention and lack of recent version updates in the threat intelligence feed.
  • Filter/Exclusion: Create a detection exception based on the Parent Process (e.g., ccmsetup.exe or ivanti_agent.exe) and verify the file’s digital signature against the known vendor certificate (e.g., Microsoft Corp. or Ivanti).

• Scheduled Endpoint Backup Routine

  • Scenario: A nightly scheduled task runs a custom backup utility wrapper named 2323.exe located in C:\ProgramData\BackupTools. This script is triggered by the Windows Task Scheduler to archive logs and compress data, but the file hash has remained static for over 18 months, triggering the “old stuff” logic.
  • Filter/Exclusion: Exclude files matching the path pattern C:\ProgramData\BackupTools\2323.exe where the File Age is greater than 90 days and the Process Command Line contains specific backup arguments (e.g., /mode=archive).

• Third-Party Antivirus Quarantine Agent

  • Scenario: A legacy component of an on-premise antivirus solution (such as Symantec Endpoint Protection or Trend Micro) runs a background