Name:Linux Possible System Binary Backdoor id:a806d611-ea81-4d8a-9b9b-fbf5b6ec520a version:1 date:None author:Raven Tait, Splunk status:production type:Anomaly Description:The following analytic detects the creation or overwrite of commonly targeted Linux system binaries such as cat, ls, cp, ps, mv, netstat, ss, and lsof.
Adversaries may replace these utilities with backdoored versions to hide malicious activity, harvest credentials, or maintain persistence while appearing to use legitimate system tools.
This technique is associated with rootkit deployment and post-exploitation frameworks such as PANIX. Data_source:
-Sysmon for Linux EventID 11
search:| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime
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 file creation events including the file path and user context. 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 `Filesystem` 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:Legitimate system updates or package managers may create or overwrite system binaries during normal operations. Filter for known update processes and package management activity to reduce noise. References: -https://github.com/Aegrah/PANIX 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:['Linux Post-Exploitation', 'Linux Persistence Techniques', 'Linux Privilege Escalation', 'Compromised Linux Host']
