Techniques
Sample rules
Windows PowGoop Beacon Decoding
- source: splunk
- technicques:
- T1059.001
- T1001
Description
Detects a DLL decoding and executing the PowGoop config.txt payload, the stage in the MuddyWater infection chain where an obfuscated PowerShell beacon is unwrapped and live C2 communication begins. PowGoop is the primary loader used by MuddyWater (also tracked as SeedWorm, Static Kitten, and MERCURY) and has been their main initial access loader since at least 2020. It abuses DLL side-loading against a fake GoogleUpdate.exe to execute a multi-stage decoding chain, a fully functional PowerShell backdoor disguised with a benign extension. The config.txt contains a hardcoded C2 address and victim GUID, beacons via modified base64-encoded HTTP, and runs C2 traffic under the legitimate Google Update process to evade network detection.
Detection logic
| tstats `security_content_summariesonly`
count min(_time) as firstTime
max(_time) as lastTime
from datamodel=Endpoint.Processes where
Processes.parent_process_path="*rundll32.exe"
Processes.process_name="powershell.exe"
Processes.process="*FromBase64String*"
Processes.process="*config.txt*"
by Processes.process Processes.vendor_product Processes.user_id Processes.process_hash
Processes.parent_process_name Processes.parent_process_exec Processes.action
Processes.dest Processes.process_current_directory Processes.process_path
Processes.process_integrity_level Processes.original_file_name Processes.parent_process
Processes.parent_process_path Processes.parent_process_guid Processes.parent_process_id
Processes.process_guid Processes.process_id Processes.user Processes.process_name
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `windows_powgoop_beacon_decoding_filter`