Windows password protected ZIP file opened with suspicious email attachments
Goal
Detects users opening password-protected ZIP files that have been received as email attachments.
Strategy
This rule monitors Windows event ID 5379 for shell extension handler operations involving ZIP folders in Outlook’s temporary directories. It tracks when @Event.EventData.Data.TargetName contains any of the following strings in the path: Microsoft_Windows_Shell_ZipFolder, Content.Outlook, Files, or Temporary.
Password-protected archives bypass email security scanning capabilities, allowing malicious content to reach endpoints without inspection. When extracted, this content may execute and compromise systems.
Triage & Response
- Examine the source email and sender details on
{{host}} to determine legitimacy. - Confirm if the password-protected attachment was expected from a trusted source.
- Analyze extracted file contents and subsequent process executions.
- Check for network connections established after the archive extraction.
- Identify similar password-protected attachments sent to other users.
- Block the sender domain if determined to be malicious.
- Isolate
{{host}} if malicious content is confirmed.
