Name:Windows Phishing Outlook Drop Dll In FORM Dir id:fca01769-5163-4b3a-ae44-de874adfc9bc version:3 date:2024-09-30 author:Teoderick Contreras, Splunk status:production type:TTP Description:The following analytic detects the creation of a DLL file by an outlook.exe process in the AppData\Local\Microsoft\FORMS directory. This detection leverages data from the Endpoint.Processes and Endpoint.Filesystem datamodels, focusing on process and file creation events. This activity is significant as it may indicate an attempt to exploit CVE-2024-21378, where a custom MAPI form loads a potentially malicious DLL. If confirmed malicious, this could allow an attacker to execute arbitrary code, leading to further system compromise or data exfiltration. Data_source:
-Sysmon EventID 11
search:| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes where Processes.process_name=outlook.exe by _time span=1h Processes.process_id Processes.process_name Processes.process Processes.dest Processes.process_guid | `drop_dm_object_name(Processes)` | join process_guid, _time [ | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem where Filesystem.file_name ="*.dll" Filesystem.file_path = "*\\AppData\\Local\\Microsoft\\FORMS\\IPM*" by _time span=1h Filesystem.dest Filesystem.file_create_time Filesystem.file_name Filesystem.file_path Filesystem.process_guid | `drop_dm_object_name(Filesystem)` | fields file_name file_path process_name process_path process dest file_create_time _time process_guid] | `windows_phishing_outlook_drop_dll_in_form_dir_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 `Filesystem` 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:unknown References: -https://www.netspi.com/blog/technical/red-team-operations/microsoft-outlook-remote-code-execution-cve-2024-21378/ 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 ("$dest$") 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: - 'Outlook RCE CVE-2024-21378' asset_type:Endpoint confidence:70 impact:70 message:an outlook process dropped dll file into $file_path$ on $dest$ mitre_attack_id: - 'T1566' observable: name:'dest' type:'Hostname' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'dest' - 'file_create_time' - 'file_name' - 'file_path' - 'process_name' - 'process_path' - 'process' risk_score:49 security_domain:endpoint cve: - 'CVE-2024-21378'
