Suspicious Thumbs.ini File Written to AppData by UNC2970 MISTPEN (via file_event)

ATT&CK techniques

Defense Evasion

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

What it detects

This rule detects creation of a file named Thumbs.ini in a user AppData directory, a working file the UNC2970 MISTPEN backdoor writes while masquerading as the legitimate Thumbs.db thumbnail cache. The anomalous extension in an unexpected location indicates backdoor staging.

Reporting behind it

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Suspicious Thumbs.ini File Written to AppData by UNC2970 MISTPEN (via file_event)

Pivot detection · T1027 · 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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