Detection: Windows Mock Trusted Directory MSC File Creation

Description

Detects the creation of MSC files within a "C:\Windows \System32" directory. Due to how Windows parses paths, the space causes an execution flow hijack and a malicious file will be executed instead of the standard Windows Files.

Search

 1
 2| tstats `security_content_summariesonly`
 3  count min(_time) as firstTime
 4        max(_time) as lastTime
 5
 6from datamodel=Endpoint.Filesystem where
 7
 8Filesystem.file_path IN (
 9    "C:\\Windows \\System32\\*.msc",
10    "C:\\Windows \\System32\\de-DE\\*.msc",
11    "C:\\Windows \\System32\\en-US\\*.msc",
12    "C:\\Windows \\System32\\es-ES\\*.msc",
13    "C:\\Windows \\System32\\fr-FR\\*.msc",
14    "C:\\Windows \\System32\\it-IT\\*.msc",
15    "C:\\Windows \\System32\\ja-JP\\*.msc",
16    "C:\\Windows \\System32\\ko-KR\\*.msc",
17    "C:\\Windows \\System32\\zh-CN\\*.msc",
18    "C:\\Windows \\System32\\zh-TW\\*.msc"
19)
20
21by Filesystem.dest Filesystem.file_create_time Filesystem.process_path
22   Filesystem.process_guid Filesystem.process_id Filesystem.file_path Filesystem.file_name
23   Filesystem.user Filesystem.vendor_product Filesystem.action
24
25
26| `drop_dm_object_name(Filesystem)`
27
28| `security_content_ctime(firstTime)`
29
30| `security_content_ctime(lastTime)`
31
32| `windows_mock_trusted_directory_msc_file_creation_filter`

Data Source

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

Macros Used

Annotations

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 legitimate software installers or system maintenance tools may create MSC files in the System32 directory with unusual paths. Verify and allow trusted system or vendor-approved processes to reduce false positives.

Associated Analytic Story

• Windows Persistence Techniques

• Windows Privilege Escalation

Risk Based Analytics (RBA)

Risk Message:

MSC file created in a mock trusted directory at $file_path$ on $dest$.

References

• https://www.fortinet.com/blog/threat-research/fickle-stealer-distributed-via-multiple-attack-chain

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: 1