Detect xrdp Unauthenticated Stack Buffer Overflow via RDP Connection Sequence (CVE-2025-68670) in CrowdStrike LogScale
CVE-2025-68670 is a critical unauthenticated stack buffer overflow (CWE-121) in xrdp versions prior to 0.10.5. During the RDP connection sequence, a remote unauthenticated attacker can send a specially crafted packet that overflows a stack buffer, potentially enabling remote code execution as the xrdp process user. CVSS 9.1. A public PoC exists. Patch to xrdp >= 0.10.5 immediately.
MITRE ATT&CK
- Tactic
- Initial Access Execution
LogScale Detection Query
#event_simpleName IN ("NetworkConnectIP4", "NetworkConnectIP6", "ProcessRollup2", "SyntheticProcessRollup2")
| filter
(
(event_simpleName IN ("NetworkConnectIP4", "NetworkConnectIP6") AND RemotePort = "3389" AND NetworkDirectionName = "INBOUND")
OR
(event_simpleName IN ("ProcessRollup2", "SyntheticProcessRollup2") AND ImageFileName LIKE "%xrdp%" AND (ExitCode != "0" OR CommandLine LIKE "%core%"))
)
| eval event_type=if(event_simpleName IN ("NetworkConnectIP4", "NetworkConnectIP6"), "rdp_inbound", "xrdp_abnormal_exit")
| stats count() by ComputerName, aid, RemoteAddressIP4, RemotePort, ImageFileName, ExitCode, event_type
| sort -countCrowdStrike Falcon Query Language rule correlating inbound RDP connections and xrdp process abnormal exits to detect CVE-2025-68670 exploitation attempts on Linux endpoints.
Data Sources
Required Tables
False Positives & Tuning
- Authorized RDP traffic from management networks
- xrdp update or restart processes causing non-zero exit codes
- Sensor policy gaps causing incomplete telemetry
- Automated IT tooling connecting to port 3389 for health checks
Other platforms for CVE-2025-68670
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1xrdp Version Enumeration via RDP Banner Grab
Expected signal: Network connection event to port 3389 from scanning host; xrdp access log entry for the probe connection.
- Test 2Malformed RDP X.224 PDU Fuzzing (PoC Simulation)
Expected signal: xrdp crash log entry (SIGSEGV/SIGABRT/stack smashing detected) in /var/log/xrdp.log; core dump if ulimit -c unlimited is set; network connection event from test host to port 3389.
- Test 3Post-Exploitation Persistence Check (Simulated RCE Artifact)
Expected signal: Auditd events for crontab modification by xrdp user; file creation event in /tmp for .xrdp_persist; process execution telemetry showing crontab -r invoked by non-interactive xrdp session.
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