Suspicious RegAsm MSBuild or AutoIt Accessing Browser Credential Stores

ATT&CK techniques

Cred Access

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
- T1552.001Credentials In Files
- T1555.003Credentials from Web Browsers
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects RegAsm, MSBuild, RegSvcs, or AutoIt3 processes referencing browser credential and cookie stores such as Login Data, key4.db, and cookies.sqlite. Microsoft observed injected Lumma Stealer code inside these hosts harvesting DPAPI-protected browser secrets. These .NET and scripting hosts have no legitimate reason to read browser credential databases, making the combination a strong credential theft indicator.

Reporting behind it

Related detections9 linkedT1555.003 — drag to rearrange

Windows PowerShell ScriptBlock keyword match for WinPwn tool usage

Windows process command line matches WinPwn tool execution keywords

Malicious Fake Fortinet Patch Infostealer Execution (via process_creation)

Suspicious BoryptGrab Infostealer Staging Directory (via file_event)

Malicious Interlock Credential Stealer Output File

Malicious Browser Master Key Decryption Artifacts Written by Katz Stealer (via file_event)

Suspicious Access to Cloud and Database Credential Files via Process

Suspicious Credential Exfiltration to webhook.site (via dns_query)

Suspicious AppleScript Payload Execution via osascript (macOS)

Suspicious RegAsm MSBuild or AutoIt Accessing Browser Credential Stores

Pivot detection · T1555.003 · 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 →