Detect Juniper Session Smart Router Authentication Bypass (CVE-2025-21589) in CrowdStrike LogScale
CVE-2025-21589 is a critical authentication bypass vulnerability (CWE-288, CVSS 9.8) in Juniper Networks Session Smart Router, Session Smart Conductor, and WAN Assurance Managed Router. An unauthenticated remote attacker can bypass authentication mechanisms to gain administrative access to the management interface without valid credentials. Affected versions include SSR 5.6.7–5.6.16, 6.0.x before 6.0.8, 6.1.x before 6.1.12-lts, 6.2.x before 6.2.8-lts, and 6.3.x before 6.3.3-r2. Exploitation grants full control of affected routers and conductors, enabling lateral movement, traffic interception, configuration tampering, and persistent backdoor establishment.
MITRE ATT&CK
LogScale Detection Query
#event_simpleName=NetworkConnectIP4 OR #event_simpleName=NetworkConnectIP6 OR #event_simpleName=HttpRequest
| $device_vendor = "Juniper"
| RemotePort in [80, 443, 830, 8080, 8443, 4505, 4506]
| (
HttpUserAgent = /(?i)(python-requests|curl\/|wget\/|Go-http-client|libwww-perl)/
OR
HttpUrl = /(?i)(\/api\/v1|\/conductor|\/admin|\/login)/
OR
#event_simpleName = "AuthActivityAuditEvent" AND UserAuthenticationResult = "AuthBypassAttempt"
)
| groupBy([RemoteAddressIP4, LocalAddressIP4, RemotePort], function=[
count(aid, as=event_count),
collect(HttpUserAgent, as=user_agents),
collect(HttpUrl, as=accessed_urls),
min(@timestamp, as=first_seen),
max(@timestamp, as=last_seen)
])
| event_count >= 3
| eval cve = "CVE-2025-21589"
| eval severity = "critical"
| eval vendor_product = "Juniper Session Smart Router"
| sort(event_count, order=desc)
| table([@timestamp, RemoteAddressIP4, LocalAddressIP4, RemotePort, event_count, user_agents, accessed_urls, first_seen, last_seen, cve, severity])CrowdStrike Falcon LogScale query detecting authentication bypass exploitation attempts against Juniper Session Smart Router by correlating network connection events with suspicious HTTP clients and management API path access patterns.
Data Sources
Required Tables
False Positives & Tuning
- CrowdStrike-protected endpoints running legitimate automation against Juniper management interfaces
- Security operations workstations using command-line HTTP tools for authorized Juniper API access
- DevOps pipeline agents on CrowdStrike-enrolled systems pushing Juniper configuration changes
- Vulnerability management agents on enrolled endpoints during authorized scan windows
Other platforms for CVE-2025-21589
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 1Unauthenticated REST API Enumeration Against SSR Management Interface
Expected signal: Multiple HTTP GET requests to management API paths from a single source IP within seconds; HTTP 200 or 401 responses logged in SSR access logs; no authentication token in request headers
- Test 2Authentication Bypass Attempt via Malformed Session Token
Expected signal: Authentication audit events showing requests with malformed or absent credentials; REST API logs showing 200-series responses to authenticated endpoints without valid session; source IP making multiple rapid unauthenticated requests
- Test 3Post-Bypass Administrative Account Creation Simulation
Expected signal: New user creation event in Juniper audit log; REST API POST to /api/v1/users followed by successful 201 response; new admin account appearing in user enumeration
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