LoFP / false positives may arise in the rdp hijacking analytic when legitimate administrators access remote sessions for maintenance or troubleshooting purposes. these activities might resemble an attacker''s attempt to hijack a disconnected session, leading to false alarms. to mitigate the risk of false positives and improve the overall security posture, organizations can implement group policy to automatically disconnect rdp sessions when they are complete. by enforcing this policy, administrators ensure that disconnected sessions are promptly terminated, reducing the window of opportunity for an attacker to hijack a session. additionally, organizations can also implement access control mechanisms and monitor the behavior of privileged accounts to further enhance security and reduce the chances of false positives in rdp hijacking detection.

Techniques

• T1543.003
• T1563
• T1563.002

Sample rules

Windows Service Create with Tscon

• source: splunk
• technicques:
  • T1563.002
  • T1563
  • T1543.003

Description

The following analytic detects potential RDP Hijacking attempts by monitoring a series of actions taken by an attacker to gain unauthorized access to a remote system. The attacker first runs the quser command to query the remote host for disconnected user sessions. Upon identifying a disconnected session, they use the sc.exe command to create a new Windows service with a binary path that launches tscon.exe. By specifying the disconnected session ID and a destination ID, the attacker can transfer the disconnected session to a new RDP session, effectively hijacking the user’s session. This analytic allows security teams to detect and respond to RDP Hijacking attempts, mitigating potential risks and impacts on targeted systems.

Detection logic

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name=sc.exe Processes.process="*/dest:rdp-tcp*" by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_service_create_with_tscon_filter`