Windows Modify Registry ProxyServer

SPLUNK detection rule by Teoderick Contreras, Splunk · Apache-2.0

The following analytic detects modifications to the Windows registry key for setting up a proxy server. It leverages data from the Endpoint.Registry datamodel, focusing on changes to the "Internet Settings\\ProxyServer" registry path. This activity is significant as it can indicate malware or adversaries configuring a proxy to facilitate unauthorized communication with Command and Control (C2) servers. If confirmed malicious, this could allow attackers to establish persistent, covert channels for data exfiltration or further exploitation of the compromised host.

name: Windows Modify Registry ProxyServer
id: 12bdaa0b-3c59-4489-aae1-bff6d67746ef
version: 11
creation_date: '2023-12-06'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: The following analytic detects modifications to the Windows registry key for setting up a proxy server. It leverages data from the Endpoint.Registry datamodel, focusing on changes to the "Internet Settings\\ProxyServer" registry path. This activity is significant as it can indicate malware or adversaries configuring a proxy to facilitate unauthorized communication with Command and Control (C2) servers. If confirmed malicious, this could allow attackers to establish persistent, covert channels for data exfiltration or further exploitation of the compromised host.
data_source:
    - Sysmon EventID 13
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where Registry.registry_path = "*\\Internet Settings\\ProxyServer" by Registry.action Registry.dest Registry.process_guid Registry.process_id Registry.registry_hive Registry.registry_path Registry.registry_key_name Registry.registry_value_data Registry.registry_value_name Registry.registry_value_type Registry.status Registry.user Registry.vendor_product | `drop_dm_object_name(Registry)` | where isnotnull(registry_value_data) | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_modify_registry_proxyserver_filter`'
how_to_implement: To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the `Endpoint` datamodel in the `Registry` node. Also make sure that this registry was included in your config files ex. sysmon config to be monitored.
known_false_positives: Administrators may enable or disable this feature that may cause some false positive, however is not common. Filter as needed.
references:
    - https://malpedia.caad.fkie.fraunhofer.de/details/win.darkgate
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | 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"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: the registry settings was modified to setup proxy server on $dest$.
analytic_story:
    - DarkGate Malware
asset_type: Endpoint
mitre_attack_id:
    - T1112
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/T1112/proxy_server/ProxyServer_sys.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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