The hypothesis is that the detection rule 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 detect and mitigate advanced persistent threats before they cause significant damage.
YARA Rule
rule IMPLANT_4_v1 {
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:
$STR1 = {55 8B EC 81 EC 54 01 00 00 83 65 D4 00 C6 45 D8 61 C6 45 D9 64
C6 45 DA 76 C6 45 DB 61 C6 45 DC 70 C6 45 DD 69 C6 45 DE 33 C6 45 DF
32 C6 45 E0 2EE9 ?? ?? ?? ??} $STR2 = {C7 45 EC 5A 00 00 00 C7 45 E0
46 00 00 00 C7 45 E8 5A 00 00 00 C7 45 E4 46 00 00 00}
condition:
(uint16(0)== 0x5A4D or uint16(0) == 0xCFD0 or uint16(0)== 0xC3D4 or
uint32(0) == 0x46445025 or uint32(1) == 0x6674725C) and 1 of them
}This YARA rule can be deployed in the following contexts:
This rule contains 2 string patterns in its detection logic.
Scenario: Scheduled System Maintenance Task
Description: A legitimate scheduled task runs a script that uses cmd.exe with /c to execute a maintenance script, which may resemble command-line activity seen in the implant.
Filter/Exclusion: Exclude processes associated with Task Scheduler or processes with CommandLine containing known maintenance scripts (e.g., schtasks.exe or maintenance.bat).
Scenario: Admin Performing Remote PowerShell Execution
Description: An administrator uses PowerShell remoting (Invoke-Command) to execute scripts on remote systems, which may trigger the rule due to similar command-line patterns.
Filter/Exclusion: Exclude processes with ProcessName powershell.exe and CommandLine containing Invoke-Command or RemoteHost matching known admin systems.
Scenario: Antivirus or EDR Tool Scanning for Malware
Description: A security tool like Kaspersky or CrowdStrike runs a scan that uses cmd.exe to execute a scan script, which may trigger the rule due to command-line similarities.
Filter/Exclusion: Exclude processes with ProcessName kavsvc.exe, crowdstrike.exe, or ProcessName matching known EDR tools.
Scenario: Database Backup Job Using SQLCMD
Description: A database backup job uses sqlcmd.exe to execute a backup script, which may be flagged due to command-line structure similar to the implant.
Filter/Exclusion: Exclude processes with ProcessName sqlcmd.exe and CommandLine containing BACKUP DATABASE or sqlbackup.exe.
Scenario: Software Update Deployment via SCCM
Description: A System Center Configuration Manager (SCCM) update deployment uses cmd.exe to execute an update script, which may be mistaken for