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.

Query · spl

| tstats `security_content_summariesonly`
  count min(_time) as firstTime,
        max(_time) as lastTime
        values(Filesystem.file_path) as file_path

FROM datamodel=Endpoint.Filesystem WHERE

[
    | inputlookup remote_access_software
    | search file_name!=""
    | rename file_name as Filesystem.file_name
    | table Filesystem.file_name
]
OR
[
    | inputlookup remote_access_software
    | search file_path!=""
    | rename file_path as Filesystem.file_path
    | table Filesystem.file_path
]

BY Filesystem.action Filesystem.dest Filesystem.file_access_time
   Filesystem.file_create_time Filesystem.file_hash
   Filesystem.file_modify_time Filesystem.file_name
   Filesystem.file_path Filesystem.file_acl Filesystem.file_size
   Filesystem.process_guid Filesystem.process_id
   Filesystem.user Filesystem.vendor_product

| `drop_dm_object_name(Filesystem)`

| 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

| 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

| eval signature=coalesce(nullif(name_signature, ""), path_signature),
       category=coalesce(nullif(name_category, ""), path_category),
       reference=coalesce(nullif(name_reference, ""), path_reference),
       description=coalesce(nullif(name_description, ""), path_description)

| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`

| `remote_access_software_usage_exceptions`

| `detect_remote_access_software_usage_file_filter`

Implementation guide

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

Analyst notes

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

Raw source Detect Remote Access Software Usage File · SPL
Esc
Published by splunk/security_content ↗, licensed under Apache 2.0 ↗. Reproduced here unmodified. 
name: Detect Remote Access Software Usage File
id: 3bf5541a-6a45-4fdc-b01d-59b899fff961
version: 18
creation_date: '2024-03-06'
modification_date: '2026-10-19'
author: Steven Dick, Onur Mustafa Erdogan, Splunk
status: production
type: Anomaly
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.
data_source:
    - Sysmon EventID 11
search: |
    | tstats `security_content_summariesonly`
      count min(_time) as firstTime,
            max(_time) as lastTime
            values(Filesystem.file_path) as file_path

    FROM datamodel=Endpoint.Filesystem WHERE

    [
        | inputlookup remote_access_software
        | search file_name!=""
        | rename file_name as Filesystem.file_name
        | table Filesystem.file_name
    ]
    OR
    [
        | inputlookup remote_access_software
        | search file_path!=""
        | rename file_path as Filesystem.file_path
        | table Filesystem.file_path
    ]

    BY Filesystem.action Filesystem.dest Filesystem.file_access_time
       Filesystem.file_create_time Filesystem.file_hash
       Filesystem.file_modify_time Filesystem.file_name
       Filesystem.file_path Filesystem.file_acl Filesystem.file_size
       Filesystem.process_guid Filesystem.process_id
       Filesystem.user Filesystem.vendor_product

    | `drop_dm_object_name(Filesystem)`

    | 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

    | 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

    | eval signature=coalesce(nullif(name_signature, ""), path_signature),
           category=coalesce(nullif(name_category, ""), path_category),
           reference=coalesce(nullif(name_reference, ""), path_reference),
           description=coalesce(nullif(name_description, ""), path_description)

    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`

    | `remote_access_software_usage_exceptions`

    | `detect_remote_access_software_usage_file_filter`
how_to_implement: |-
    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
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/
drilldown_searches:
    - name: View the detection results for - "$dest$" and "$user$"
      search: '%original_detection_search% | search  dest = "$dest$" user = "$user$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$" and "$user$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$", "$user$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
    - name: Investigate files on $dest$
      search: '| from datamodel:Endpoint.Filesystem | search dest=$dest$ file_name=$file_name$'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: A file [$file_name$] known to be associated with a remote access software [$signature$] was created on [$dest$] by [$user$].
        - field: user
          type: user
          score: 20
          message: A file [$file_name$] known to be associated with a remote access software [$signature$] was created on [$dest$] by [$user$].
threat_objects:
    - field: file_name
      type: file_name
    - field: signature
      type: signature
analytic_story:
    - Cactus Ransomware
    - CISA AA24-241A
    - Command And Control
    - GhostRedirector IIS Module and Rungan Backdoor
    - Gozi Malware
    - Insider Threat
    - Interlock Ransomware
    - Ransomware
    - Remote Monitoring and Management Software
    - Scattered Lapsus$ Hunters
    - Scattered Spider
    - Seashell Blizzard
asset_type: Endpoint
mitre_attack_id:
    - T1219
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1219/screenconnect/screenconnect_sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      description: PORTED MANUAL TEST - This detection uses A&I lookups from Enterprise Security.
      test_type: experimental

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