Thread Hijacking Phishing with Malicious Script Attachment
This rule detects potential thread hijacking phishing attempts where an email with a subject starting with 'RE:' or 'FW:' (indicating a reply or forward) contains an attachment with a suspicious file extension (.js, .hta, or .lnk). The rule specifically looks for these emails originating from domains outside of a predefined list of trusted domains and flags instances where more than one such suspicious reply/forward is sent from the same sender with the same subject and filename within a day, suggesting a coordinated attack.
Microsoft Sentinel (KQL)
