Name:Windows XLL File Creation Outside of Typical Location id:7cdbe5e2-878d-4020-94f3-52938760155e version:2 date:None author:Raven Tait, Splunk status:production type:Anomaly Description:Detects the creation of an XLL file outside of typical locations.
This can indicate an attempt to abuse Excel COM objects to load and execute a malicious XLL. Data_source:
-Sysmon EventID 11
search:| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime
from datamodel=Endpoint.Filesystem where
Filesystem.file_path="*.xll"
NOT Filesystem.file_path IN ( "*:\\Program Files\\Microsoft Office\\*", "*\\AppData\\Roaming\\Microsoft\\AddIns\\*" )
how_to_implement:The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process. known_false_positives:Some legitimate Excel add-ins and administrative tools may create XLL files outside typical locations. Review and allow approved applications to reduce false positives. References: -https://www.bleepingcomputer.com/news/security/new-specula-tool-uses-outlook-for-remote-code-execution-in-windows/ -https://github.com/trustedsec/specula/wiki drilldown_searches: earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View the detection results for - "$user$" and "$dest$"' search:'%original_detection_search% | search user = "$user$" dest = "$dest$"' name:'View risk events for the last 7 days for - "$user$" and "$dest$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$dest$") | 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' analytic_story:['Spearphishing Attachments']
