Malicious Chrome Extension Sideload via --load-extension from User-Writable Path (via process_creation)

ATT&CK techniques

Persistence → Cred Access

Recon
Resource Dev
Initial Access
Execution
Persistence
- T1176Software Extensions
Priv Esc
Defense Evasion
Cred Access
- T1539Steal Web Session Cookie
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects a Chromium-based browser launched with the --load-extension flag pointing to a user-writable AppData or Public directory. The Ducktail campaign drops a malicious extension into the Chrome User Data folder and injects it through a LNK shortcut using --load-extension to steal session cookies and hijack business accounts, so this command line indicates unauthorized extension loading.

Reporting behind it

Related detections9 linkedT1539 — drag to rearrange

Suspicious Browser Launch with Unpacked Extension Loaded via load-extension (via process_creation)

Malicious GenAI Browser Extension C2 and PAC Redirection (via proxy)

Suspicious Chrome Launch With Remote Debugging via Airstalk (via process_creation)

Malicious VVS Discord Stealer Script Drop via injection-obf.js (via file_event)

Suspicious Anonymous Sharing Link Creation in SharePoint or OneDrive via M365 Audit

Suspicious Microsoft Edge Headless Launch with Unpacked Extension via SNOWBELT (via process_creation)

Suspicious Browser Remote Debugging Port Cookie Theft via process_creation

Suspicious Browser Extension Force-Install via Registry (via registry_set)

Suspicious CloudScout hxkz_zip Exfiltration Archive Creation via File System

Malicious Chrome Extension Sideload via --load-extension from User-Writable Path (via process_creation)

Pivot detection · T1539 · 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 →