A compiled HTML help file wrote a script file to the disk

Synopsis

Field	Value
Activation Period	14 Days
Training Period	30 Days
Test Period	N/A (single event)
Deduplication Period	1 Day
Required Data	XDR Agent with eXtended Threat Hunting (XTH)
ATT&CK Tactic	Stealth (TA0005)
ATT&CK Technique	System Binary Proxy Execution: Compiled HTML File (T1218.001)
Severity	Low

Description

A compiled HTML help file wrote a script file to the disk. Compiled HTLM help files usually don't write script files to the disk. This behavior is often employed by malware that leverages malicious CHM files to deliver a 2nd stage payload.

Attacker's Goals

Deliver a 2nd stage payload or to avoid detection.

Investigative actions

• Check whether the initiator process is benign or normal for the host and/or user performing it.
• Check the file that was written to the disk for malicious activities.