LoFP LoFP / legitimate used of encrypted zip files

Techniques

Sample rules

Password Protected ZIP File Opened (Suspicious Filenames)

Description

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.

Detection logic

condition: selection and selection_filename
selection:
  EventID: 5379
  TargetName|contains: Microsoft_Windows_Shell_ZipFolder:filename
selection_filename:
  TargetName|contains:
  - invoice
  - new order
  - rechnung
  - factura
  - delivery
  - purchase
  - order
  - payment

Password Protected ZIP File Opened (Email Attachment)

Description

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

Detection logic

condition: selection
selection:
  EventID: 5379
  TargetName|contains|all:
  - Microsoft_Windows_Shell_ZipFolder:filename
  - \Temporary Internet Files\Content.Outlook

Password Protected ZIP File Opened

Description

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

Detection logic

condition: selection and not filter
filter:
  TargetName|contains: \Temporary Internet Files\Content.Outlook
selection:
  EventID: 5379
  TargetName|contains: Microsoft_Windows_Shell_ZipFolder:filename