Suspicious StrelaStealer Base64 Payload Decode via Certutil (via process_creation)

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1140Deobfuscate/Decode Files or Information
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects certutil being used with the decode and force flags to convert a Base64 encoded file into an executable payload, the deobfuscation step in the StrelaStealer infection chain. Because certutil decode is a living off the land technique for staging hidden binaries, this usage warrants review as likely payload unpacking.

Reporting behind it

Related detections9 linkedT1140 — drag to rearrange

Suspicious File Download via certutil URLCache (via process_creation)

Suspicious Base64 Decoding Piped to Shell on macOS

Suspicious Hex Decoding Piped to Shell via xxd on macOS

Malicious GitVenom Python Fernet Decrypt-and-Execute Loader via process_creation

Certutil Decoding Encoded Payload to Executable

Suspicious Certutil Decode of Payload to Executable

Suspicious File Concatenation via copy Binary Mode

Suspicious CAB Extraction via extrac32 LOLBin

Suspicious GPG Decryption of Downloaded Payload via GPG

Suspicious StrelaStealer Base64 Payload Decode via Certutil (via process_creation)

Pivot detection · T1140 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

Full detection rule

Unlock this rule to view and copy it

The detection logic is included with a plan. Everything else — context, mappings and implementation details — stays free on this page.

Sign in for 3 free unlocks

Signing in gives you 3 unlocks to spend on any rule in the library. No card, and they do not expire.

Also included

Unlocked rules convert on this page — to Splunk SPL or Splunk — Raw Index SPL or Microsoft Sentinel KQL or Microsoft Sentinel ASIM ASIM KQL or Microsoft Defender XDR KQL or Elastic Security KQL or Elastic Security Lucene or Elastic Security ES|QL or CrowdStrike Falcon CQL or SentinelOne PowerQuery or Palo Alto Cortex XDR XQL or Carbon Black Cloud Platform Search or Carbon Black EDR Process Search or Google Security Operations UDM Search or IBM QRadar AQL or Sumo Logic Cloud SIEM Rules expression or Rapid7 InsightIDR LEQL or Graylog Search or OpenSearch Lucene or OpenSearch PPL PPL or Grafana Loki LogQL or SQLite SQL or Zircolite SQLite — with the log-source profile the engine picked, the field map it used, and everything it could not express. Converting a rule you have unlocked costs no further credit.

See it run on a free rule →Convert your own rule →