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Upgrade to ProDetect BeyondTrust Remote Support Pre-Auth RCE (CVE-2026-1731) in Splunk
Detects exploitation of CVE-2026-1731, a pre-authentication remote code execution vulnerability (CWE-78, OS command injection) in BeyondTrust Remote Support and Privileged Remote Access. CVSS 9.8. Actively exploited in the wild (CISA KEV). Attackers can execute arbitrary OS commands without authentication via crafted HTTP requests to the appliance web interface.
MITRE ATT&CK
SPL Detection Query
index=* sourcetype IN ("beyondtrust:syslog", "beyondtrust:rs", "beyondtrust:pra", "wineventlog", "syslog", "iis")
| eval is_bt_process=if(match(lower(process_name), "bomgar|beyondtrust|remote_support|rs_app|pra"), 1, 0)
| eval suspicious_child=if(match(lower(child_process_name), "cmd\.exe|powershell|bash|sh|python|wget|curl|nc|ncat|whoami|id"), 1, 0)
| eval suspicious_ua=if(match(lower(http_user_agent), "python-requests|curl/|go-http-client|exploit|poc|nuclei"), 1, 0)
| eval exploit_uri=if(match(lower(uri_path), "/api/|/login|/appliance|/cgi-bin"), 1, 0)
| eval outbound_anomaly=if(is_bt_process=1 AND dest_port NOT IN (80, 443, 8080, 8443) AND dest_category!="internal", 1, 0)
| where (is_bt_process=1 AND suspicious_child=1)
OR (suspicious_ua=1 AND exploit_uri=1 AND http_method="POST" AND (status=200 OR status=500))
OR (outbound_anomaly=1)
OR (sourcetype="beyondtrust:syslog" AND match(lower(_raw), "exec|command|shell|injection|os\.system"))
| eval detection_reason=case(
is_bt_process=1 AND suspicious_child=1, "BeyondTrust spawned suspicious child process",
suspicious_ua=1 AND exploit_uri=1, "Exploit-like UA targeting appliance endpoint",
outbound_anomaly=1, "BeyondTrust process made anomalous outbound connection",
true(), "Appliance log command injection indicator"
)
| table _time, host, src_ip, dest_ip, dest_port, process_name, child_process_name, uri_path, http_user_agent, status, detection_reason
| sort -_timeDetects CVE-2026-1731 exploitation patterns in BeyondTrust appliance logs, IIS/web logs, and endpoint telemetry. Identifies suspicious child processes from BeyondTrust parent processes, exploit-like HTTP user-agents targeting appliance URIs, and anomalous outbound connections from BeyondTrust service processes.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Legitimate automation scripts using curl or python-requests to interact with BeyondTrust APIs
- Authorized security assessments or red team exercises targeting the appliance
- BeyondTrust health monitoring processes that spawn diagnostic shell commands
- Third-party integrations that POST to appliance API endpoints using generic HTTP clients
Other platforms for CVE-2026-1731
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 1CVE-2026-1731 PoC HTTP Request Simulation
Expected signal: IIS/nginx access log entry: POST /api/unauthenticated/session with user-agent 'CVE-2026-1731-PoC-Test' and POST body containing ';id;whoami;'. WAF should log or block the request.
- Test 2BeyondTrust Service Account Spawning Shell (Simulated Post-Exploitation)
Expected signal: Windows Security Event 4688: new process cmd.exe with parent process belonging to BeyondTrust service account (btrs_service). Process command line contains whoami, hostname, ipconfig, net user.
- Test 3BeyondTrust Process Outbound Reverse Shell Simulation
Expected signal: Linux auditd execve syscall: bash -i spawned by beyondtrust service process. Network connection record: beyondtrust process connecting outbound to LAB_ATTACKER_IP:4444 (non-standard port, external IP).
References (5)
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