AutoIt Payload Reassembly via copy /b File Concatenation

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1027Obfuscated Files or Information
- T1140Deobfuscate/Decode Files or Information
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects the use of copy /b to concatenate multiple file fragments together with a bundled AutoIt3 interpreter. CastleLoader uses this evasion technique to rebuild its compiled a3x script on disk from scattered parts.

Reporting behind it

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AutoIt Payload Reassembly via copy /b File Concatenation

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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