Detection: Windows SymbolicLink-Testing-Tools Utility Execution

Description

Detects the execution of tools from the symboliclink-testing-tools toolkit. This toolkit is often used for exploiting Windows symbolic link, junction, and oplock vulnerabilities to achieve local privilege escalation from a standard user to SYSTEM. Symbolic link attacks against Windows exploit a class of logical vulnerability where a SYSTEM or administrator-level process performs a file operation on a path that a low-privileged attacker can redirect using a combination of NTFS junctions, object manager symbolic links, and opportunistic locks (oplocks). By chaining these primitives a standard user can redirect a privileged file write, delete, or read to an arbitrary path, effectively turning a narrow file operation vulnerability into arbitrary write or code execution as SYSTEM.

Search

 1
 2| tstats `security_content_summariesonly`
 3  count min(_time) as firstTime
 4        max(_time) as lastTime
 5
 6from datamodel=Endpoint.Processes where
 7
 8Processes.process_name IN (
 9    "BaitAndSwitch.exe",
10    "CreateDosDeviceSymlink.exe",
11    "CreateMountPoint.exe",
12    "CreateNtfsSymlink.exe",
13    "CreateObjectDirectory.exe",
14    "CreateRegSymlink.exe",
15    "DeleteMountPoint.exe",
16    "DumpReparsePoint.exe",
17    "NativeSymlink.exe",
18    "SetOpLock.exe"
19)
20
21by Processes.process Processes.vendor_product Processes.user_id Processes.process_hash
22   Processes.parent_process_name Processes.parent_process_exec Processes.action
23   Processes.dest Processes.process_current_directory Processes.process_path
24   Processes.process_integrity_level Processes.original_file_name Processes.parent_process
25   Processes.parent_process_path Processes.parent_process_guid Processes.parent_process_id
26   Processes.process_guid Processes.process_id Processes.user Processes.process_name
27
28
29| `drop_dm_object_name(Processes)`
30
31| `security_content_ctime(firstTime)`
32
33| `security_content_ctime(lastTime)`
34
35| `windows_symboliclink_testing_tools_utility_execution_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	Other	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'XmlWinEventLog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'XmlWinEventLog'	'XmlWinEventLog:Security'

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 system administration or development tasks may use these tools for managing symbolic links or file locks. Filter alerts for authorized maintenance and testing activities.

Associated Analytic Story

• Windows Persistence Techniques

• Windows Post-Exploitation

• Windows Privilege Escalation

Risk Based Analytics (RBA)

Risk Message:

Potential Symbolic Link Testing Tools activity observed on $dest$ via $process$.

References

• https://github.com/googleprojectzero/symboliclink-testing-tools

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