Ruleset to detect SpyNetV2 samples.

Hunt Hypothesis

Adversaries may use SpyNetV2 samples to establish covert command and control channels, leveraging Azure environments for persistence and data exfiltration. Proactively hunting for these indicators in Azure Sentinel helps identify potential long-term espionage activities before they lead to data breaches or system compromise.

YARA Rule

rule SpyNet : malware
{
	meta:
		description = "Ruleset to detect SpyNetV2 samples. "
		sample = "e6ef34577a75fc0dc0a1f473304de1fc3a0d7d330bf58448db5f3108ed92741b"

	strings:
	$a = "odNotice.txt"
	$b = "camera This device has camera!"
	$c = "camera This device has Nooo camera!"
	$d = "send|1sBdBBbbBBF|K|"
	$e = "send|372|ScreamSMS|senssd"
	$f = "send|5ms5gs5annc"
	$g = "send|45CLCLCa01"
	$h = "send|999SAnd|TimeStart"
	$i = "!s!c!r!e!a!m!"
	condition:
		4 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 9 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: Scheduled System Maintenance Task
  Description: A legitimate scheduled task runs a script that includes base64 encoded data as part of a system update or patching process.
  Filter/Exclusion: Exclude processes associated with Task Scheduler or tasks with names containing Update, Patch, or Maintenance.

• Scenario: Admin Performing Base64 Decoding for Debugging
  Description: A system administrator uses a tool like base64 (Linux) or certutil -decode (Windows) to decode data for troubleshooting purposes.
  Filter/Exclusion: Exclude processes initiated by users with administrative privileges or those using command-line tools for decoding.

• Scenario: Log File Parsing with Base64 Encoded Data
  Description: A log management tool like Splunk, ELK Stack, or Graylog processes log files that include base64 encoded data for transmission or storage.
  Filter/Exclusion: Exclude processes related to log parsing tools or those accessing log files from known log directories.

• Scenario: PowerShell Script for Configuration Management
  Description: A PowerShell script used for configuration management (e.g., PSConfig, Pester, or Chef) includes base64 encoded strings for secure credential storage.
  Filter/Exclusion: Exclude processes initiated by PowerShell scripts with known configuration management tool signatures or running under a service account.

• Scenario: Antivirus Quarantine File Processing
  Description: An antivirus tool like Windows Defender, Kaspersky, or Bitdefender processes quarantined files that contain base64 encoded data as part of its analysis.
  Filter/Exclusion: Exclude processes associated with antivirus tools or those running in quarantine processing contexts.