Windows Firewall Rule Deletion

name: Windows Firewall Rule Deletion
id: ca5327e1-0a91-4e23-bbd4-8901806c00e1
version: 8
creation_date: '2025-03-21'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: This detection identifies instances where a Windows Firewall rule has been deleted, potentially exposing the system to security risks. Unauthorized removal of firewall rules can indicate an attacker attempting to bypass security controls or malware disabling protections for persistence and command-and-control communication. The event logs details such as the deleted rule name, protocol, port, and the user responsible for the action. Security teams should monitor for unexpected deletions, correlate with related events, and investigate anomalies to prevent unauthorized access and maintain network security posture.
data_source:
    - Windows Event Log Security 4948
search: |-
    `wineventlog_security` EventCode=4948
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY RuleName signature subject
           status dest ProcessID
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `windows_firewall_rule_deletion_filter`
how_to_implement: This detection is based on data collected from Endpoint Detection and Response (EDR) agents, which provide security-related telemetry from monitored endpoints. Specifically, it focuses on Windows Security Event Log entries with EventID 4948, which indicates that a Windows Firewall rule has been delted. To implement this detection in Splunk, you must ingest Windows Security Event Logs that capture EventID 4948, ensuring that critical fields such as _time, EventRecordID, ProcessID, ThreadID, Computer, ProfileChanged, RuleName, and RuleId are available for analysis. These logs must be processed using the appropriate Splunk Technology Add-ons (TAs) to ensure compatibility with the EDR product and proper field extraction. Additionally, mapping these logs to the appropriate data model, such as the Endpoint data model, enhances structured analysis. Leveraging the Splunk Common Information Model (CIM) helps normalize field names, ensuring consistency across different data sources. By implementing this approach, you can effectively detect and monitor Windows Firewall rule modifications, providing visibility into potential security risks or unauthorized changes.
known_false_positives: Legitimate admin delete, Group Policy updates, software installs, security tools, and automated scripts can trigger false positives for Event ID 4948.
references:
    - https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-10/security/threat-protection/auditing/event-4948
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: a firewall rule $RuleName$ has been modified on $dest$.
analytic_story:
    - ShrinkLocker
    - Medusa Ransomware
    - NetSupport RMM Tool Abuse
asset_type: Endpoint
mitre_attack_id:
    - T1686
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/T1562.004/firewall_win_event/delete_rule/MPSSVC_Rule-Level_Policy_Change-4948.log
          source: XmlWinEventLog:Security
          sourcetype: XmlWinEventLog
      test_type: unit