Name:HTTP C2 Framework User Agent id:229dc225-6abe-4d28-89fd-edf874086162 version:5 date:None author:Ravent Tait, Splunk status:production type:TTP Description:This Splunk query analyzes web logs to identify and categorize user agents, detecting various types of c2 frameworks. This activity can signify malicious actors attempting to interact with hosts on the network using known default configurations of command and control tools. Data_source:
-Suricata
search:| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Web WHERE Web.http_user_agent != null BY Web.http_user_agent Web.http_method, Web.url, Web.url_length Web.src, Web.dest | `drop_dm_object_name("Web")` | lookup suspicious_c2_user_agents c2_user_agent AS http_user_agent OUTPUT tool, description | where isnotnull(tool) | stats count min(firstTime) as first_seen max(lastTime) as last_seen BY tool url http_user_agent src dest description | `security_content_ctime(first_seen)` | `security_content_ctime(last_seen)` | `http_c2_framework_user_agent_filter`
how_to_implement:To successfully implement this search, you need to be ingesting web or proxy logs, or ensure it is being filled by a proxy like device, into the Web Datamodel. For additional filtering, allow list private IP space or restrict by known good. known_false_positives:Filtering may be required in some instances depending on legacy system usage, filter as needed. References: -https://github.com/BC-SECURITY/Malleable-C2-Profiles -https://www.keysight.com/blogs/en/tech/nwvs/2021/07/28/koadic-c3-command-control-decoded -https://github.com/mthcht/awesome-lists/blob/main/Lists/suspicious_http_user_agents_list.csv drilldown_searches: name:'View the detection results for - "$src$"' search:'%original_detection_search% | search src = "$src$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$src$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$src$") | 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:['Cobalt Strike', 'Brute Ratel C4', 'Tuoni', 'Meterpreter', 'Spearphishing Attachments', 'Malicious PowerShell', 'BishopFox Sliver Adversary Emulation Framework', 'Suspicious User Agents']
