Name:Change Default File Association id:462d17d8-1f71-11ec-ad07-acde48001122 version:3 date:2024-09-30 author:Teoderick Contreras, Splunk status:production type:TTP Description:The following analytic detects suspicious registry modifications that change the default file association to execute a malicious payload. It leverages data from the Endpoint data model, specifically monitoring registry paths under "*\\shell\\open\\command\\*" and "*HKCR\\*". This activity is significant because altering default file associations can allow attackers to execute arbitrary scripts or payloads when a user opens a file, leading to potential code execution. If confirmed malicious, this technique can enable attackers to persist on the compromised host and execute further malicious commands, posing a severe threat to the environment. Data_source:
-Sysmon EventID 12
-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 ="*\\shell\\open\\command\\*" Registry.registry_path = "*HKCR\\*" by Registry.dest Registry.user Registry.registry_path Registry.registry_key_name Registry.registry_value_name | `security_content_ctime(lastTime)` | `security_content_ctime(firstTime)` | `drop_dm_object_name(Registry)` | `change_default_file_association_filter`
how_to_implement:To successfully implement this search, you must be ingesting data that records registry activity from your hosts to populate the endpoint data model in the registry node. This is typically populated via endpoint detection-and-response product, such as Carbon Black or endpoint data sources, such as Sysmon. The data used for this search is typically generated via logs that report reads and writes to the registry. known_false_positives:unknown References: -https://dmcxblue.gitbook.io/red-team-notes-2-0/red-team-techniques/privilege-escalation/untitled-3/accessibility-features 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 ("$dest$", "$user$") 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: - 'Hermetic Wiper' - 'Windows Registry Abuse' - 'Prestige Ransomware' - 'Windows Privilege Escalation' - 'Windows Persistence Techniques' - 'Data Destruction' asset_type:Endpoint confidence:100 impact:80 message:Registry path $registry_path$ was modified, added, or deleted in $dest$. mitre_attack_id: - 'T1546.001' - 'T1546' observable: name:'dest' type:'Hostname' - role: - 'Victim' name:'user' type:'User' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'Registry.dest' - 'Registry.user' - 'Registry.registry_path' - 'Registry.registry_key_name' - 'Registry.registry_value_name' risk_score:80 security_domain:endpoint
