Name:Windows Modify Registry Delete Firewall Rules id:41c61539-98ca-4750-b3ec-7c29a2f06343 version:3 date:2024-12-08 author:Teoderick Contreras, Splunk status:production type:TTP Description:The following analytic detects a potential deletion of firewall rules, indicating a possible security breach or unauthorized access attempt. It identifies actions where firewall rules are removed using commands like netsh advfirewall firewall delete rule, which can expose the network to external threats by disabling critical security measures. Monitoring these activities helps maintain network integrity and prevent malicious attacks. Data_source:
-Sysmon EventID 12
search:`sysmon` EventCode=12 TargetObject = "*\\System\\CurrentControlSet\\Services\\SharedAccess\\Parameters\\FirewallPolicy\\FirewallRules\\*" EventType=DeleteValue | rename Computer as dest | rename User as user | stats count min(_time) as firstTime max(_time) as lastTime by EventCode EventType TargetObject Image user dest | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_modify_registry_delete_firewall_rules_filter`
how_to_implement:To successfully implement this search, you need to be ingesting logs with the registry value name, registry path, and registry value data from your endpoints. If you are using Sysmon, you must have at least version 2.0 of the official Sysmon TA. https://splunkbase.splunk.com/app/5709 known_false_positives:network admin may add/remove/modify public inbound firewall rule that may cause this rule to be triggered. References: -https://www.bleepingcomputer.com/news/security/new-shrinklocker-ransomware-uses-bitlocker-to-encrypt-your-files/ drilldown_searches: name:'View the detection results for - "$user$" and "$dest$"' search:'%original_detection_search% | search user = "$user$" dest = "$dest$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$user$" and "$dest$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$dest$") starthoursago=168 | 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:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'ShrinkLocker' - 'CISA AA24-241A' asset_type:Endpoint confidence:80 impact:80 message:firewall deletion found in registry in $dest$ mitre_attack_id: - 'T1112' observable: name:'user' type:'User' - role: - 'Victim' name:'dest' type:'Hostname' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'EventCode' - 'EventType' - 'TargetObject' - 'Image' - 'user' - 'dest' risk_score:64 security_domain:endpoint
