Detect Versa Concerto Improper Authentication (CVE-2025-34026) in Google Chronicle
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
YARA-L Detection Query
rule versa_concerto_auth_bypass_cve_2025_34026 {
meta:
author = "df00tech Detection Engineering"
description = "Detects authentication bypass exploitation of CVE-2025-34026 in Versa Concerto"
severity = "CRITICAL"
priority = "HIGH"
reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-34026"
cve = "CVE-2025-34026"
events:
$e.metadata.event_type = "NETWORK_HTTP"
(
$e.target.hostname = /(?i)(concerto|versa-concerto|versa)/ or
$e.target.ip = $target_ip
)
(
$e.network.http.target_url = /(?i)\/(api|auth|admin|management|login)\// or
$e.network.http.target_url = /(?i)\/(api|auth|admin|management|login)$/
)
$e.network.http.response_code = 200
(
not $e.principal.user.userid = /\w+/ or
$e.principal.user.userid = "-" or
$e.principal.user.userid = "anonymous"
)
condition:
$e
}Chronicle YARA-L rule detecting successful unauthenticated HTTP access to Versa Concerto protected endpoints. Triggers on HTTP 200 responses to /api/, /auth, /admin, or /management paths on Concerto hosts where no valid user identity is present.
Data Sources
Required Tables
False Positives & Tuning
- Service accounts using certificate-based authentication where user ID is not logged
- Internal health monitoring probes accessing Concerto status endpoints
- Concerto platform's own internal service-to-service calls
- Automated backup or configuration management tools using API tokens without user context
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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