Name:Windows Phishing Recent ISO Exec Registry id:cb38ee66-8ae5-47de-bd66-231c7bbc0b2c version:4 date:2024-10-17 author:Teoderick Contreras, Splunk status:production type:Hunting Description:The following analytic detects the creation of registry artifacts when an ISO container is opened, clicked, or mounted on a Windows operating system. It leverages data from the Endpoint.Registry data model, specifically monitoring registry keys related to recent ISO or IMG file executions. This activity is significant as adversaries increasingly use container-based phishing campaigns to bypass macro-based document execution controls. If confirmed malicious, this behavior could indicate an initial access attempt, potentially leading to further exploitation, persistence, or data exfiltration within 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_key_name= "*\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Explorer\\RecentDocs\\.iso" OR Registry.registry_key_name= "*\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Explorer\\RecentDocs\\.img" by Registry.registry_key_name Registry.user Registry.registry_path Registry.registry_value_data Registry.action Registry.dest | `drop_dm_object_name(Registry)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_phishing_recent_iso_exec_registry_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. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product. known_false_positives:False positives may be high depending on the environment and consistent use of ISOs. Restrict to servers, or filter out based on commonly used ISO names. Filter as needed. References: -https://www.microsoft.com/security/blog/2021/05/27/new-sophisticated-email-based-attack-from-nobelium/ -https://unit42.paloaltonetworks.com/brute-ratel-c4-tool/ -https://isc.sans.edu/diary/Recent+AZORult+activity/25120 -https://tccontre.blogspot.com/2020/01/remcos-rat-evading-windows-defender-av.html drilldown_searches:
: tags: analytic_story: - 'Brute Ratel C4' - 'AgentTesla' - 'Qakbot' - 'IcedID' - 'Azorult' - 'Remcos' - 'Warzone RAT' - 'Gozi Malware' asset_type:Endpoint confidence:80 impact:50 message:An ISO file was mounted on $dest$ and should be reviewed and filtered as needed. mitre_attack_id: - 'T1566.001' - 'T1566' observable: name:'dest' type:'Hostname' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'Registry.registry_key_name' - 'Registry.user' - 'Registry.registry_path' - 'Registry.registry_value_data' - 'Registry.action' - 'Registry.dest' risk_score:40 security_domain:endpoint
