RomeoEcho

Hunt Hypothesis

The RomeoEcho detection identifies adversary behavior characterized by specific code patterns that may indicate early-stage reconnaissance or benign automation anomalies within the environment. Proactively hunting for this signature in Azure Sentinel allows the SOC team to validate these occurrences against known baselines and distinguish potential low-fidelity threats from normal operational noise before they escalate.

YARA Rule

rule RomeoEcho
{
	meta:
		copyright = "2015 Novetta Solutions"
		author = "Novetta Threat Research & Interdiction Group - [email protected]"

	strings:
		$ = "%s %-20s %10lu %s"
		$ = "_quit"
		$ = "_exe"
		$ = "_put"
		$ = "_get"

	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
• Source Rule

False Positive Guidance

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

• Scheduled Antivirus Definition Updates via WSUS

  • Scenario: The Windows Update Service (wuauserv) or a third-party endpoint like Microsoft Defender for Endpoint triggers the RomeoEcho signature when pushing new virus definition packages to domain-joined workstations during off-hours. This often involves temporary file creation and script execution that mimics the rule’s behavioral indicators.
  • Filter/Exclusion: Exclude processes originating from the C:\Windows\SoftwareDistribution\Download directory or filter events where the parent process is wuapp.exe (Windows Update App) running under the SYSTEM account during the defined maintenance window (e.g., 02:00–04:00 UTC).

• Automated Patch Deployment with SCCM/MECM

  • Scenario: During a major patch cycle, Microsoft Endpoint Configuration Manager (MECM) executes PowerShell scripts to install cumulative updates. The deployment engine (ccmexec.exe) spawns child processes that download and unpack payloads, generating file system artifacts that match the RomeoEcho YARA pattern for legitimate software distribution activities.
  • Filter/Exclusion: Create a rule exclusion for process paths containing \CCM\ or specifically target the executable name ccmexec.exe. Additionally, filter by user context to exclude actions performed under the NT AUTHORITY\SYSTEM account when the source IP belongs to the internal SCCM management point subnet.

• Backup Agent Data Scanning (Veeam/Commvault)

  • Scenario: Enterprise backup agents such as Veeam Backup & Replication or Commvault Simpana perform incremental scans of critical file servers. These agents