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. It is best to update both the remote_access_software_usage_exception.csv lookup and the remote_access_software lookup with any known or approved remote access software to reduce false positives and increase coverage. In order to enhance performance, the detection filters for specific file names extensions / names that are used in the remote_access_software lookup. If add additional entries, consider updating the search filters to include those file names / extensions as well, if not alread covered.

Search

 1
 2| tstats `security_content_summariesonly`
 3  count min(_time) as firstTime,
 4        max(_time) as lastTime
 5        values(Filesystem.file_path) as file_path
 6
 7FROM datamodel=Endpoint.Filesystem WHERE
 8
 9[
10    
11| inputlookup remote_access_software
12    
13| search file_name!=""
14    
15| rename file_name as Filesystem.file_name
16    
17| table Filesystem.file_name
18]
19OR
20[
21    
22| inputlookup remote_access_software
23    
24| search file_path!=""
25    
26| rename file_path as Filesystem.file_path
27    
28| table Filesystem.file_path
29]
30
31BY Filesystem.action Filesystem.dest Filesystem.file_access_time
32   Filesystem.file_create_time Filesystem.file_hash
33   Filesystem.file_modify_time Filesystem.file_name
34   Filesystem.file_path Filesystem.file_acl Filesystem.file_size
35   Filesystem.process_guid Filesystem.process_id
36   Filesystem.user Filesystem.vendor_product
37
38
39| `drop_dm_object_name(Filesystem)`
40
41
42| lookup local=t remote_access_software file_name OUTPUT app as name_signature, category as name_category, reference as name_reference, description as name_description
43
44
45| lookup local=t remote_access_software file_path OUTPUT app as path_signature, category as path_category, reference as path_reference, description as path_description
46
47
48| eval signature=coalesce(nullif(name_signature, ""), path_signature),
49       category=coalesce(nullif(name_category, ""), path_category),
50       reference=coalesce(nullif(name_reference, ""), path_reference),
51       description=coalesce(nullif(name_description, ""), path_description)
52
53
54| `security_content_ctime(firstTime)`
55
56| `security_content_ctime(lastTime)`
57
58
59| `remote_access_software_usage_exceptions`
60
61
62| `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

• Ransomware

• GhostRedirector IIS Module and Rungan Backdoor

• Cactus Ransomware

• CISA AA24-241A

• Interlock Ransomware

• Scattered Lapsus$ Hunters

• Scattered Spider

• Seashell Blizzard

• Insider Threat

• Remote Monitoring and Management Software

• Gozi Malware

• Command And Control

Intermediate Findings

Threat Objects

References

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

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

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

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: 18