Detection: Windows CAB File on Disk

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 can be 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.

Search

 1
 2| tstats `security_content_summariesonly`
 3  count values(Filesystem.file_path) as file_path
 4        min(_time) as firstTime
 5        max(_time) as lastTime
 6
 7FROM datamodel=Endpoint.Filesystem WHERE
 8
 9Filesystem.action IN ("created", "modified")
10Filesystem.file_name="*.cab"
11NOT Filesystem.file_path IN (
12    "*\\AppData\\Local\\Microsoft\\*",
13    "*\\Windows Kits\\10\\ADK\\Installers\\*",
14    "C:\\Program Files (x86)\\*",
15    "C:\\Program Files\\*",
16    "C:\\ProgramData\\Microsoft\\*",
17    "C:\\ProgramData\\Package Cache\\*",
18    "C:\\Windows\\appcompat\\*",
19    "C:\\Windows\\Logs\\CBS\\*",
20    "C:\\Windows\\servicing\\*",
21    "C:\\Windows\\SoftwareDistribution\\*",
22    "C:\\Windows\\System32\\*",
23    "C:\\Windows\\SystemApps\\*",
24    "C:\\Windows\\SysWOW64\\*",
25    "C:\\Windows\\WinSxS\\*",
26)
27
28BY Filesystem.action Filesystem.dest Filesystem.file_access_time
29   Filesystem.file_create_time Filesystem.file_hash Filesystem.file_modify_time
30   Filesystem.file_name Filesystem.file_path Filesystem.file_acl
31   Filesystem.file_size Filesystem.process_guid Filesystem.process_id
32   Filesystem.user Filesystem.vendor_product
33
34
35| `drop_dm_object_name("Filesystem")`
36
37| `security_content_ctime(firstTime)`
38
39| `security_content_ctime(lastTime)`
40
41| `windows_cab_file_on_disk_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 11	Windows	'XmlWinEventLog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

Macros Used

Annotations

CVE

• CVE-2026-47301

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

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

Some false positives are expected from user controlled folders.

Associated Analytic Story

• APT37 Rustonotto and FadeStealer

• DarkGate Malware

Intermediate Findings

Threat Objects

References

• https://github.com/PaloAltoNetworks/Unit42-timely-threat-intel/blob/main/2023-10-25-IOCs-from-DarkGate-activity.txt

Detection Testing

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub |

Version: 12