Detection rules › Sigma

Password Protected ZIP File Opened (Suspicious Filenames)

Severity
high
Author
Florian Roth (Nextron Systems)
Source
upstream

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

MITRE ATT&CK coverage

TacticTechniques
Defense EvasionT1027 Obfuscated Files or Information, T1036 Masquerading
Command & ControlT1105 Ingress Tool Transfer

Event coverage

ProviderEvent IDTitle
Security-Auditing5379Credential Manager credentials were read.

Stages and Predicates

Stage 1: selection

TargetName|contains: 'Microsoft_Windows_Shell_ZipFolder:filename'

Stage 2: selection_filename

or:
TargetName|contains: delivery
TargetName|contains: factura
TargetName|contains: invoice
TargetName|contains: 'new order'
TargetName|contains: order
TargetName|contains: payment
TargetName|contains: purchase
TargetName|contains: rechnung

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.

FieldKindValues
TargetNamematch
  • Microsoft_Windows_Shell_ZipFolder:filename corpus 3 (sigma 3)
  • delivery
  • factura
  • invoice
  • new order
  • order
  • payment
  • purchase
  • rechnung

Neighbors

Stricter alternatives (narrower than this rule)

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