UniformJuliett

Hunt Hypothesis

This detection targets adversary behavior involving the execution of uniform or standardized payloads that may indicate early-stage reconnaissance or lateral movement attempts within the environment. The SOC team should proactively hunt for these patterns in Azure Sentinel to identify subtle deviations from baseline activity before they escalate into significant incidents, despite the rule’s current low severity classification.

YARA Rule

rule UniformJuliett
{
	meta:
		copyright = "2015 Novetta Solutions"
		author = "Novetta Threat Research & Interdiction Group - [email protected]"
		Source = "Cmd03000_1a6f62e1630d512c3b67bfdbff26270177585c82802ffa834b768ff47be0a008.bin"

	strings:
		/*
			56                 push    esi             ; hSCObject
			FF D5              call    ebp ; CloseServiceHandle
			68 B8 0B 00 00     push    0BB8h           ; dwMilliseconds
			FF 15 38 70 40 00  call    ds:Sleep
			6A 00              push    0               ; fCreateHighestLevel
			68 60 A9 40 00     push    offset PathName ; lpPathName
			E8 43 FE FF FF     call    RecursivelyCreateDirectories
			83 C4 08           add     esp, 8
			68 60 A9 40 00     push    offset PathName ; lpFileName
			FF 15 3C 70 40 00  call    ds:DeleteFileA
		*/
		
		$a = {56 FF D5 68 B8 0B 00 00 FF 15 [4] 6A 00 68 [4] E8 [4] 83 C4 08 68 [4] FF 15}
		
		$ = "wauserv.dll"
		$ = "Rpcss"
	
	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 1 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the UniformJuliett detection rule in an enterprise environment, along with suggested filters or exclusions:

• Scheduled Antivirus Definition Updates

  • Scenario: The nightly update cycle of Microsoft Defender for Endpoint (or CrowdStrike Falcon) downloads and unpacks new signature definitions. This process involves the rapid creation of temporary files and execution of scripts that mimic the behavior patterns targeted by UniformJuliett, specifically regarding file hashing and memory injection.
  • Filter/Exclusion: Create an exclusion rule to ignore alerts originating from the specific service account NT AUTHORITY\SYSTEM or user Local Service running within the C:\Program Files\Microsoft Defender Antivirus\Updates directory path.

• Enterprise Software Deployment via SCCM

  • Scenario: During business hours, Microsoft Endpoint Configuration Manager (MECM/SCCM) pushes a mandatory patch or application installer to workstations. The deployment agent executes PowerShell scripts and extracts compressed archives containing binaries, triggering the rule’s logic for “unusual process spawning” and “file system modifications.”
  • Filter/Exclusion: Exclude processes launched by ccmexec.exe (the SCCM client service) and its child processes, specifically filtering out events where the parent process ID matches the known SCCM service PID range.

• Database Maintenance and Index Rebuilds

  • Scenario: The automated maintenance window for Microsoft SQL Server triggers a full index rebuild or backup job. This involves high-volume I/O operations and the execution of internal T-SQL scripts that generate temporary executables, which UniformJuliett may flag as suspicious process creation due to the sheer volume of file handles opened in a short timeframe.
  • Filter/Exclusion: Add an exclusion for processes running under the NT SERVICE\MSSQLSERVER account located within the default