Windows CAB File on Disk

name: Windows CAB File on Disk
id: 622f08d0-69ef-42c2-8139-66088bc25acd
version: 11
creation_date: '2023-11-16'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: Anomaly
description: The following analytic detects .cab files being written to disk. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on events where the file name is '*.cab' and the action is 'write'. This activity is significant as .cab files can be used to deliver malicious payloads, including embedded .url files that execute harmful code. If confirmed malicious, this behavior could lead to unauthorized code execution and potential system compromise. Analysts should review the file path and associated artifacts for further investigation.
data_source:
    - Sysmon EventID 11
search: |-
    | tstats `security_content_summariesonly` count values(Filesystem.file_path) as file_path min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem
      WHERE (
            Filesystem.file_name=*.cab
        )
      BY Filesystem.action Filesystem.dest Filesystem.file_access_time
         Filesystem.file_create_time Filesystem.file_hash Filesystem.file_modify_time
         Filesystem.file_name Filesystem.file_path Filesystem.file_acl
         Filesystem.file_size Filesystem.process_guid Filesystem.process_id
         Filesystem.user Filesystem.vendor_product
    | `drop_dm_object_name("Filesystem")`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_cab_file_on_disk_filter`
how_to_implement: The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: False positives will only be present if a process legitimately writes a .cab file to disk. Modify the analytic as needed by file path. Filter as needed.
references:
    - https://github.com/PaloAltoNetworks/Unit42-timely-threat-intel/blob/main/2023-10-25-IOCs-from-DarkGate-activity.txt
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: A .cab file was written to disk on endpoint $dest$.
analytic_story:
    - DarkGate Malware
    - APT37 Rustonotto and FadeStealer
asset_type: Endpoint
mitre_attack_id:
    - T1566.001
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1059/autoit/cab_files.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit