BlackEnergy / Voodoo Bear Implant by APT28

Hunt Hypothesis

The hypothesis is that the detection identifies potential BlackEnergy/Voodoo Bear implant activity by APT28, characterized by suspicious file execution and network communication patterns indicative of command and control. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate advanced persistent threats before they cause significant damage.

YARA Rule

rule IMPLANT_4_v12 {
   meta:
      description = "BlackEnergy / Voodoo Bear Implant by APT28"
      author = "US CERT"
      reference = "https://www.us-cert.gov/ncas/current-activity/2017/02/10/Enhanced-Analysis-GRIZZLY-STEPPE"
      date = "2017-02-10"
      score = 85
   strings:
      $CMP1 = {81 ?? 4D 5A 00 00 }
      $SUB1 = {81 ?? 00 10 00 00}
      $CMP2 = {66 81 38 4D 5A}
      $SUB2 = {2D 00 10 00 00}
      $HAL = "HAL.dll"
      $OUT = {E6 64 E9 ?? ?? FF FF}
   condition:
   (uint16(0) == 0x5A4D or uint16(0) == 0xCFD0 or uint16(0) == 0xC3D4 or
   uint32(0) == 0x46445025 or uint32(1) == 0x6674725C) and ($CMP1 or $CMP2)
   and ($SUB1 or $SUB2) and $OUT and $HAL
}

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.

References

False Positive Guidance

Scenario: Scheduled System Maintenance Task
Description: A legitimate system maintenance task, such as a scheduled disk cleanup or log rotation, may trigger the rule due to similar file creation or execution patterns.
Filter/Exclusion: Check for file.name containing “clean”, “logrotate”, or “maintenance” and exclude processes with process.parent.name equal to “Task Scheduler” or “schtasks.exe”.
Scenario: Admin User Running PowerShell Scripts for Configuration
Description: An admin user may run PowerShell scripts to configure system settings, which could resemble the behavior of the BlackEnergy/Voodoo Bear implant.
Filter/Exclusion: Filter by user.name being a known admin account (e.g., “Administrator”) and check for process.name being “powershell.exe” with a script path containing “config”, “setup”, or “deploy”.
Scenario: Antivirus or Endpoint Protection Scan
Description: Antivirus or endpoint protection tools may execute scripts or binaries that match the detection logic for the BlackEnergy/Voodoo Bear implant.
Filter/Exclusion: Exclude processes with process.name containing “avast”, “bitdefender”, “mcafee”, or “windows defender” and check for process.parent.name being “svchost.exe” or “taskeng.exe”.
Scenario: Legitimate Software Deployment via SCCM
Description: Software deployment tools like SCCM (System Center Configuration Manager) may execute payloads that resemble malicious implants.
Filter/Exclusion: Filter by process.name containing “ccmexec” or “sccm” and check for file.name containing “setup”, “install”, or “deploy” in the command line arguments.
Scenario: User-Initiated File Upload or Download
Description: Users may upload or download files that have similar names