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 threat activity early in the attack lifecycle.
YARA Rule
rule IMPLANT_4_v8 {
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:
$f1 = {5E 81 EC 04 01 00 00 8B D4 68 04 01 00 00 52 6A 00 FF 57 1C 8B D4
33 C9 03 D0 4A 41 3B C8 74 05 80 3A 5C 75 F5 42 81 EC 04 01 00 00 8B
DC 52 51 53 68 04 01 00 00 FF 57 20 59 5A 66 C7 04 03 5C 20 56 57 8D
3C 03 8B F2 F3 A4 C6 07 00 5F 5E 33 C0 50 68 80 00 00 00 6A 02 50 50
68 00 00 00 40 53 FF 57 14 53 8B 4F 4C 8B D6 33 DB 30 1A 42 43 3B D9
7C F8 5B 83 EC 04 8B D4 50 6A 00 52 FF 77 4C 8B D6 52 50 FF 57 24 FF
57 18}
$f2 = {5E 83 EC 1C 8B 45 08 8B 4D 08 03 48 3C 89 4D E4 89 75 EC 8B 45 08
2B 45 10 89 45 E8 33 C0 89 45 F4 8B 55 0C 3B 55 F4 0F 86 98 00 00 00
8B 45 EC 8B 4D F4 03 48 04 89 4D F4 8B 55 EC 8B 42 04 83 E8 08 D1 E8
89 45 F8 8B 4D EC 83 C1 08 89 4D FC}
$f3 = {5F 8B DF 83 C3 60 2B 5F 54 89 5C 24 20 8B 44 24 24 25 00 00 FF FF
66 8B 18 66 81 FB 4D 5A 74 07 2D 00 00 01 00 EB EF 8B 48 3C 03 C8 66
8B 19 66 81 FB 50 45 75 E0 8B E8 8B F7 83 EC 60 8B FC B9 60 00 00 00
F3 A4 83 EF 60 6A 0D 59 E8 88 00 00 00 E2 F9 68 6C 33 32 00 68 73 68
65 6C 54 FF 57}
$a1 = {83 EC 04 60 E9 1E 01 00 00}
condition:
$a1 at pe.entry_point or any of ($f*)
}This YARA rule can be deployed in the following contexts:
This rule contains 4 string patterns in its detection logic.
Scenario: Scheduled System Maintenance Task
Description: A legitimate scheduled task runs a script that mimics the behavior of the BlackEnergy/Voodoo Bear implant, such as copying files or modifying registry keys.
Filter/Exclusion: process.parent_process_name == "Task Scheduler" or process.name == "schtasks.exe"
Scenario: Admin Performing Remote Desktop Protocol (RDP) Session
Description: An administrator uses RDP to access a server and performs actions that could be mistaken for implant activity, such as downloading or executing files.
Filter/Exclusion: process.parent_process_name == "mstsc.exe" or process.user == "domain_admin"
Scenario: Software Update or Patch Deployment
Description: A legitimate software update or patch deployment tool (e.g., Microsoft Update, SCCM) executes scripts or binaries that resemble malicious implant behavior.
Filter/Exclusion: process.name == "wusa.exe" or process.name == "setup.exe" or process.command_line contains "update"
Scenario: Database Backup or Restore Job
Description: A database backup or restore job (e.g., using sqlcmd, mysqldump, or pg_dump) involves file operations that could trigger the detection rule.
Filter/Exclusion: process.name == "sqlcmd.exe" or process.name == "mysqldump.exe" or process.command_line contains "backup"
Scenario: Log Collection or Monitoring Tool Execution
Description: A log collection or monitoring tool (e.g., Splunk, ELK Stack, or custom scripts) performs file operations or registry modifications that match the rule’s logic.
Filter/Exclusion: process.name == "splunkforwarder.exe" or process.name == "logstash.exe" or `process.command_line