Name:Ngrok Reverse Proxy on Network id:5790a766-53b8-40d3-a696-3547b978fcf0 version:3 date:2024-09-30 author:Michael Haag, Splunk status:production type:Anomaly Description:The following analytic detects DNS queries to common Ngrok domains, indicating potential use of the Ngrok reverse proxy tool. It leverages the Network Resolution datamodel to identify queries to domains such as "*.ngrok.com" and "*.ngrok.io". While Ngrok usage is not inherently malicious, it has been increasingly adopted by adversaries for covert communication and data exfiltration. If confirmed malicious, this activity could allow attackers to bypass network defenses, establish persistent connections, and exfiltrate sensitive data, posing a significant threat to the network's security. Data_source:
-Sysmon EventID 22
search:| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Network_Resolution where DNS.query IN ("*.ngrok.com","*.ngrok.io", "ngrok.*.tunnel.com", "korgn.*.lennut.com") by DNS.src DNS.query DNS.answer | `drop_dm_object_name("DNS")` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `ngrok_reverse_proxy_on_network_filter`
how_to_implement:The Network Resolution Datamodel will need to have data mapped to it regarding DNS queries. Modify query as needed to use another source. known_false_positives:False positives will be present based on organizations that allow the use of Ngrok. Filter or monitor as needed. References: -https://www.cisa.gov/uscert/sites/default/files/publications/aa22-320a_joint_csa_iranian_government-sponsored_apt_actors_compromise_federal%20network_deploy_crypto%20miner_credential_harvester.pdf 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 ("$src$") 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: - 'Reverse Network Proxy' - 'CISA AA22-320A' - 'CISA AA24-241A' asset_type:Endpoint confidence:100 impact:50 message:An endpoint, $src$, is beaconing out to the reverse proxy service of Ngrok. mitre_attack_id: - 'T1572' - 'T1090' - 'T1102' observable: name:'src' type:'Hostname' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - 'DNS.src' - 'DNS.query' - 'DNS.answer' risk_score:50 security_domain:network
