Summary
Signal K Server contains a missing authentication flaw in the /skServer/ziplogs endpoint, allowing remote attackers to download log archives without proving their identity. Because the archive may contain the JWT secret key, an attacker could forge administrator tokens, create persistent admin accounts, and gain full server control.
Signal K Server contains a missing authentication flaw in the /skServer/ziplogs endpoint, allowing remote attackers to download log archives without proving their identity. Because the archive may contain the JWT secret key, an attacker could forge administrator tokens, create persistent admin accounts, and gain full server control.
Affected context
The vulnerability affects Signal K Server deployments where the log archive endpoint is reachable over the network without an authentication barrier. Risk is increased when the generated archive includes security.json or other sensitive configuration data containing the JWT signing secret, and when forged administrative tokens are accepted by the server.
The vulnerability affects Signal K Server deployments where the log archive endpoint is reachable over the network without an authentication barrier. Risk is increased when the generated archive includes security.json or other sensitive configuration data containing the JWT signing secret, and when forged administrative tokens are accepted by the server.
Exploit preconditions
- Attack surface: The remotely accessible
/skServer/ziplogsHTTP endpoint - Required access: Network connectivity to the Signal K Server; no valid credentials are required
- Trigger point: A request to download the server's log archive
- Why exploitation is possible: The endpoint does not enforce authentication before returning potentially sensitive files, allowing disclosure of the JWT signing secret and subsequent token forgery
- Attack surface: The remotely accessible
/skServer/ziplogsHTTP endpoint - Required access: Network connectivity to the Signal K Server; no valid credentials are required
- Trigger point: A request to download the server's log archive
- Why exploitation is possible: The endpoint does not enforce authentication before returning potentially sensitive files, allowing disclosure of the JWT signing secret and subsequent token forgery
Why this happens
The underlying flaw is an authorization boundary failure: a sensitive administrative endpoint is exposed without requiring authentication. This maps to CWE-306: Missing Authentication for Critical Function, because the server permits access to protected functionality before verifying the caller's identity. Disclosure of a JWT signing secret can further undermine token integrity, allowing attackers to impersonate privileged users.
The underlying flaw is an authorization boundary failure: a sensitive administrative endpoint is exposed without requiring authentication. This maps to CWE-306: Missing Authentication for Critical Function, because the server permits access to protected functionality before verifying the caller's identity. Disclosure of a JWT signing secret can further undermine token integrity, allowing attackers to impersonate privileged users.
Potential impact
- Attackers may download sensitive server logs and configuration files
- Exposed secrets could allow forged administrator authentication tokens
- Attackers could create persistent administrative accounts
- The Signal K Server could be fully compromised
- Connected data, services, or devices may be modified or disrupted
- Attackers may download sensitive server logs and configuration files
- Exposed secrets could allow forged administrator authentication tokens
- Attackers could create persistent administrative accounts
- The Signal K Server could be fully compromised
- Connected data, services, or devices may be modified or disrupted
General mitigation guidance
Mitigation should focus on protecting sensitive operational endpoints and reducing the value of exposed configuration data.
Common defensive patterns include:
- Require authentication and explicit authorization for log archive generation and download
- Apply deny-by-default access controls to administrative and diagnostic endpoints
- Keep JWT signing secrets outside downloadable logs and archives
- Rotate credentials and signing secrets when exposure is suspected
- Run the server with least-privilege permissions and isolate administrative interfaces from untrusted networks
- Use secure session and token validation practices, including appropriate expiration and revocation controls
- Monitor and review existing administrator accounts after a possible compromise
Mitigation should focus on protecting sensitive operational endpoints and reducing the value of exposed configuration data.
Common defensive patterns include:
- Require authentication and explicit authorization for log archive generation and download
- Apply deny-by-default access controls to administrative and diagnostic endpoints
- Keep JWT signing secrets outside downloadable logs and archives
- Rotate credentials and signing secrets when exposure is suspected
- Run the server with least-privilege permissions and isolate administrative interfaces from untrusted networks
- Use secure session and token validation practices, including appropriate expiration and revocation controls
- Monitor and review existing administrator accounts after a possible compromise
How teams detect issues like this
Organizations can detect this class of issue through:
- Dynamic tests verifying that unauthenticated requests to administrative endpoints are denied
- Static analysis and code review checks for routes that expose files or diagnostics without middleware enforcing authentication
- API inventory reviews identifying log, backup, debug, and configuration-download endpoints
- Policy enforcement requiring authentication and authorization controls for all sensitive HTTP routes
- Monitoring for unusual log archive downloads, JWT validation anomalies, unexpected administrator creation, and changes to security configuration
- Automated security testing in CI pipelines to validate authentication coverage and secret-handling rules
Organizations can detect this class of issue through:
- Dynamic tests verifying that unauthenticated requests to administrative endpoints are denied
- Static analysis and code review checks for routes that expose files or diagnostics without middleware enforcing authentication
- API inventory reviews identifying log, backup, debug, and configuration-download endpoints
- Policy enforcement requiring authentication and authorization controls for all sensitive HTTP routes
- Monitoring for unusual log archive downloads, JWT validation anomalies, unexpected administrator creation, and changes to security configuration
- Automated security testing in CI pipelines to validate authentication coverage and secret-handling rules
