Name:Windows Remote Desktop Network Bruteforce Attempt id:908bf0d5-0983-4afd-b6a4-e9eb5d361a7d version:2 date:2025-02-11 author:Jose Hernandez, Bhavin Patel, Splunk status:production type:Anomaly Description:The following analytic identifies potential Remote Desktop Protocol (RDP) brute force attacks by monitoring network traffic for RDP application activity. This query detects potential RDP brute force attacks by identifying source IPs that have made more than 10 connection attempts to the same RDP port on a host within a one-hour window. The results are presented in a table that includes the source and destination IPs, destination port, number of attempts, and the times of the first and last connection attempts, helping to prioritize IPs based on the intensity of activity. Data_source:
-Sysmon EventID 3
search:| tstats `security_content_summariesonly` count, min(_time) as firstTime, max(_time) as lastTime values(Al_Traffic.action) as action from datamodel=Network_Traffic where (All_Traffic.app=rdp OR All_Traffic.dest_port=3389) by All_Traffic.src, All_Traffic.dest, All_Traffic.dest_port All_Traffic.user All_Traffic.vendor_product | `drop_dm_object_name("All_Traffic")` | eval duration=lastTime-firstTime | where count > 10 AND duration < 3600 | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_remote_desktop_network_bruteforce_attempt_filter`
how_to_implement:You must ensure that your network traffic data is populating the Network_Traffic data model. Adjust the count and duration thresholds as necessary to tune the sensitivity of your detection. known_false_positives:RDP gateways may have unusually high amounts of traffic from all other hosts' RDP applications in the network.Any legitimate RDP traffic using wrong/expired credentials will be also detected as a false positive. References: -https://www.zscaler.com/blogs/security-research/ransomware-delivered-using-rdp-brute-force-attack -https://www.reliaquest.com/blog/rdp-brute-force-attacks/ 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: - 'SamSam Ransomware' - 'Ryuk Ransomware' - 'Compromised User Account' asset_type:Endpoint mitre_attack_id: - 'T1110.001' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' security_domain:network
