Windows Security Event 5379: Opened Password-Protected ZIP from Outlook Attachment

Flags Windows events where a password-protected ZIP is opened from Outlook Temporary Internet Files.

FreeReviewedSigma · High · v2

Product: windows
Service: security
Author: Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2022-05-09
Updated: 2026-07-31

ATT&CK techniques

Initial Access → Defense Evasion

Recon
Resource Dev
Initial Access
- T1566.001Spearphishing Attachment
Execution
Persistence
Priv Esc
Defense Evasion
- T1027Obfuscated Files or Information
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule matches Windows Security auditing events (EventID 5379) where a password-protected ZIP archive is opened via the Shell ZIP folder. It targets cases involving attachments from Outlook, specifically paths under \Temporary Internet Files\Content.Outlook, which can indicate user delivery of encrypted archive contents. The detection relies on the TargetName field containing both the Shell ZIP filename marker and the Outlook temporary directory path, signaling ZIP access through email attachment handling.

Reporting behind it

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Windows Security Event 5379: Opened Password-Protected ZIP from Outlook Attachment

Pivot detection · T1027 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-security-password-protected-zip-opened-from-outlook-attachment-571498c8

title: "Windows Security Event 5379: Opened Password-Protected ZIP from Outlook Attachment"
id: 1d03ecde-dc38-454f-b547-88d12bc2da5f
status: test
description: This rule matches Windows Security auditing events (EventID 5379) where a password-protected ZIP archive is opened via the Shell ZIP folder. It targets cases involving attachments from Outlook, specifically paths under \Temporary Internet Files\Content.Outlook, which can indicate user delivery of encrypted archive contents. The detection relies on the TargetName field containing both the Shell ZIP filename marker and the Outlook temporary directory path, signaling ZIP access through email attachment handling.
references:
  - https://twitter.com/sbousseaden/status/1523383197513379841
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/builtin/security/win_security_susp_opened_encrypted_zip_outlook.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2022-05-09
tags:
  - attack.initial-access
  - attack.stealth
  - attack.t1027
  - attack.t1566.001
logsource:
  product: windows
  service: security
detection:
  selection:
    EventID: 5379
    TargetName|contains|all:
      - Microsoft_Windows_Shell_ZipFolder:filename
      - \Temporary Internet Files\Content.Outlook
  condition: selection
falsepositives:
  - Legitimate used of encrypted ZIP files
level: high
license: DRL-1.1
related:
  - id: 571498c8-908e-40b4-910b-d2369159a3da
    type: derived

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