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Upgrade to ProDetect 9router Hardcoded Default JWT Secret Authentication Bypass (CVE-2026-49352) in Sumo Logic CSE
Detects exploitation attempts against 9router (npm package) versions 0.2.21 through 0.4.41, which ship a hardcoded default fallback JWT signing secret (CWE-798). When an operator fails to override the default secret, an attacker can forge arbitrary JWTs (including admin/privileged claims) and bypass authentication entirely. Detection focuses on identifying JWTs signed with the known-public default secret, anomalous authentication success patterns following token forgery, and process/network indicators consistent with public PoC exploitation against 9router deployments.
MITRE ATT&CK
Sumo Detection Query
_sourceCategory=9router/auth
| json field=_raw "jwt_header_alg" as alg
| json field=_raw "auth_result" as auth_result
| json field=_raw "client_user_agent" as ua
| json field=_raw "prior_session_id" as prior_session
| where alg matches "HS256" or alg matches "HS384" or alg matches "HS512"
| where auth_result = "success"
| where isNull(prior_session) or ua matches "*python-requests*" or ua matches "*curl*" or ua matches "*jwt_tool*"
| count by src_ip, ua
| where _count >= 1Sumo Logic query surfacing successful HMAC-signed JWT authentications to 9router without prior session context, indicative of default-secret exploitation.
Data Sources
Required Tables
False Positives & Tuning
- Automated integrations without persistent sessions
- Generic HTTP clients used by internal tooling
- Health check/monitoring agents
Other platforms for CVE-2026-49352
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 1Forge JWT using published default secret
Expected signal: Application auth log entry showing a successful authentication event with HS256 JWT and admin role claim, with no prior session record for the subject.
- Test 2Simulate JWT forgery tooling user agent
Expected signal: HTTP access log and application auth log capturing the jwt_tool user agent string alongside an authentication attempt.
- Test 3Validate unrotated default secret configuration
Expected signal: File access/read event on the 9router config file captured by EDR or file integrity monitoring.
- Test 4Windows PowerShell JWT forgery and replay
Expected signal: Windows PowerShell script block logging (Event ID 4104) capturing the token generation, plus 9router application auth log for the replayed request.
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