Detect xrdp Unauthenticated Stack Buffer Overflow via RDP Connection Sequence (CVE-2025-68670) in IBM QRadar
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
QRadar Detection Query
SELECT
LOGSOURCENAME(logsourceid) AS log_source,
"startTime",
"sourceip",
"destinationip",
"destinationport",
"username",
"eventdirection",
"Message"
FROM events
WHERE
(
("destinationport" = 3389 AND "eventdirection" = 'R2L')
OR
(LOWER("Message") IMATCHES '.*xrdp.*(segfault|overflow|sigsegv|sigabrt|core dumped|stack smash|fatal error).*')
)
AND LOGSOURCETYPENAME(devicetype) IN ('LinuxServer', 'SyslogNGEE', 'Universal DSM', 'IBM Security Network Protection')
AND "startTime" > (NOW() - 86400000)
ORDER BY "startTime" DESC
LIMIT 500AQL query to surface inbound RDP connections and xrdp crash/overflow log messages from Linux hosts over the past 24 hours, enabling correlation of exploitation indicators for CVE-2025-68670.
Data Sources
Required Tables
False Positives & Tuning
- Authorized RDP jump-box sessions generating benign port 3389 events
- xrdp crashes due to misconfigured RDP clients sending unexpected protocol messages
- Log source misconfiguration causing high-volume false event ingestion
- Legitimate kernel OOM or watchdog killing xrdp
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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