Detect Versa Concerto Improper Authentication (CVE-2025-34026) in Elastic Security
Detects exploitation attempts targeting CVE-2025-34026, an improper authentication vulnerability (CWE-288) in Versa Concerto SD-WAN orchestration platform. This vulnerability allows attackers to bypass authentication controls, potentially enabling unauthorized access to the Concerto management interface. Listed as a CISA KEV, indicating active exploitation in the wild.
MITRE ATT&CK
Elastic Detection Query
sequence by source.ip with maxspan=5m
[network where host.name like~ "*concerto*" or host.name like~ "*versa*"
and url.path like~ "/api/*" or url.path like~ "/auth*" or url.path like~ "/admin*"
and http.response.status_code in (401, 403)]
[network where host.name like~ "*concerto*" or host.name like~ "*versa*"
and url.path like~ "/api/*" or url.path like~ "/auth*" or url.path like~ "/admin*"
and http.response.status_code == 200
and (user.name == null or user.name == "-" or user.name == "anonymous")]EQL sequence detection that identifies a pattern of initial authentication failure followed by a successful unauthenticated access to a protected Versa Concerto endpoint within 5 minutes — a hallmark of authentication bypass exploitation.
Data Sources
Required Tables
False Positives & Tuning
- Retry logic in client applications that may legitimately succeed after an initial 401
- Session expiration followed by token refresh resulting in re-authentication
- Misconfigured applications that generate transient 401s before successful auth
- Security scanners performing authentication testing
Other platforms for CVE-2025-34026
Testing Methodology
Validate this detection against 4 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 1Unauthenticated GET to Versa Concerto API Endpoint
Expected signal: HTTP access log on Concerto server showing GET /api/v1/system/info with source IP of test host, status 200, and empty/anonymous username field. Network flow showing connection to port 443.
- Test 2Authentication Bypass Probe via Malformed Auth Header
Expected signal: Series of HTTP requests to multiple protected paths logged on Concerto host. Network proxy logs showing path enumeration pattern from single source IP within short time window.
- Test 3Post-Authentication-Bypass Configuration Read
Expected signal: HTTP GET to /api/v1/vnf/inventory logged with 200 response and response body size. DLP or data exfiltration alerts if JSON response contains sensitive topology data. Network flow showing data transfer volume.
- Test 4Concerto Admin User Creation via Unauthenticated API
Expected signal: HTTP POST to /api/v1/users logged. Concerto audit log entry for user creation event. If successful, new user visible in Concerto user management interface.
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Get the full detection package for CVE-2025-34026 including response playbook, investigation guide, and atomic red team tests.