Detection: Detect Remote Access Software Usage File

Description

The following analytic detects the writing of files from known remote access software to disk within the environment. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on file path, file name, and user information. This activity is significant as adversaries often use remote access tools like AnyDesk, GoToMyPC, LogMeIn, and TeamViewer to maintain unauthorized access. If confirmed malicious, this could allow attackers to persist in the environment, potentially leading to data exfiltration, further compromise, or complete control over affected systems.

Search

1
2| tstats `security_content_summariesonly` count, min(_time) as firstTime, max(_time) as lastTime, values(Filesystem.file_path) as file_path from datamodel=Endpoint.Filesystem by Filesystem.dest, Filesystem.user, Filesystem.file_name 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `drop_dm_object_name(Filesystem)` 
6| lookup remote_access_software remote_utility AS file_name OUTPUT isutility, description as signature, comment_reference as desc, category 
7| search isutility = TRUE 
8| `remote_access_software_usage_exceptions` 
9| `detect_remote_access_software_usage_file_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 file path, file name, and the user that created the file. 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 Filesystem 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. The "exceptions" macro leverages both an Assets and Identities lookup, as well as a KVStore collection called "remote_software_exceptions" that lets you track and maintain device-based exceptions for this set of detections.

Known False Positives

Known or approved applications used by the organization or usage of built-in functions. Known false positives can be added to the remote_access_software_usage_exception.csv lookup to globally suppress these situations across all remote access content

Associated Analytic Story

• CISA AA24-241A

• Command And Control

• Gozi Malware

• Insider Threat

• Ransomware

Risk Based Analytics (RBA)

References

• https://attack.mitre.org/techniques/T1219/

• https://thedfirreport.com/2022/08/08/bumblebee-roasts-its-way-to-domain-admin/

• https://thedfirreport.com/2022/11/28/emotet-strikes-again-lnk-file-leads-to-domain-wide-ransomware/

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: 4