Password Protected ZIP File Opened

Severity: medium
Author: Florian Roth (Nextron Systems)
Source: upstream

Detects the extraction of password protected ZIP archives. See the filename variable for more details on which file has been opened.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Evasion	`T1027` Obfuscated Files or Information

Event coverage

Provider	Event ID	Title
Security-Auditing	5379	Credential Manager credentials were read.

Stages and Predicates

Stage 1: `selection`

TargetName|contains: 'Microsoft_Windows_Shell_ZipFolder:filename'

Stage 2: `not filter`

TargetName|contains: '\Temporary Internet Files\Content.Outlook'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`TargetName`	match	`Microsoft_Windows_Shell_ZipFolder:filename` corpus 3 (sigma 3) `\Temporary Internet Files\Content.Outlook` corpus 2 (sigma 2)

Neighbors

Stricter alternatives (narrower than this rule)

The rules below may be useful if you find the current rule is too noisy / lacks specificity.

Password Protected ZIP File Opened (Email Attachment) [sigma] (adds 1 filter) (first-stage match only; downstream stages may differ)