Suspicious Execution of Renamed Data File with Double Extension via STOCKSTAY (via process_creation)

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1027Obfuscated Files or Information
- T1218.005Mshta
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects execution of an image whose name ends in a data-to-executable double extension such as .dat.exe, matching the STOCKSTAY chain where an HTA renamed a styles.dat payload to styles.dat.exe and ran it through WScript.Shell. Adversaries use double extensions to disguise executable payloads as inert data files, so running such a file is a strong masquerading indicator.

Reporting behind it

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ClickFix Paste-Jacking Execution of mshta Retrieving Remote Payload (via process_creation)

Obfuscated Encoded PowerShell Payload Deployed via Process Execution (via process_creation)

Suspicious Execution of Renamed Data File with Double Extension via STOCKSTAY (via process_creation)

Pivot detection · T1218.005 · 9 related

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

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