fake whatsapp

Hunt Hypothesis

The detection rule identifies potential fake WhatsApp applications that may be used to distribute malware or steal user credentials by mimicking legitimate WhatsApp behavior. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage adversarial activity that could lead to credential theft or data exfiltration.

YARA Rule

rule fake_whatsapp: fake android
{
  meta:
		  author = "https://twitter.com/Diviei"
		  reference = "https://koodous.com/"
	condition:
		androguard.app_name("WhatsApp") and
		not androguard.certificate.sha1("38A0F7D505FE18FEC64FBF343ECAAAF310DBD799")
}

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

References

• https://koodous.com/
• Source Rule

False Positive Guidance

• Scenario: Legitimate WhatsApp Backup Restore
  Description: An admin is restoring a WhatsApp backup from a user’s device to a server for data recovery.
  Filter/Exclusion: process.name != "whatsapp" AND process.name != "adb" AND process.name != "rsync"

• Scenario: Scheduled Job for WhatsApp Data Migration
  Description: A scheduled task is running to migrate WhatsApp chat data between devices using a third-party tool like WhatsApp Backup Extractor.
  Filter/Exclusion: process.name != "whatsapp_backup_extractor" AND process.name != "migration_tool_v2.1"

• Scenario: System Admin Using WhatsApp for Internal Communication
  Description: A system administrator uses WhatsApp for internal team communication during a shift.
  Filter/Exclusion: process.name != "whatsapp" AND user.name != "admin" AND user.name != "security_team"

• Scenario: Malware Analysis with WhatsApp Emulator
  Description: A security analyst is using a WhatsApp emulator (like WhatsApp for Android Emulator) to analyze malicious payloads.
  Filter/Exclusion: process.name != "whatsapp_emulator" AND process.name != "malware_analysis_tool"

• Scenario: Automated WhatsApp Web Integration for Customer Support
  Description: A customer support team uses an automated WhatsApp Web integration tool (like Chatfuel or ManyChat) to handle customer inquiries.
  Filter/Exclusion: process.name != "chatfuel" AND process.name != "manychat" AND process.name != "whatsapp_web"