Summary
Before version 0.2.7, RClone Manager starts a local rclone remote-control service without authentication and permits cross-origin requests from any origin. A malicious web page opened while the service is running may use the user's browser to access the local API with the user's operating-system privileges, exposing credentials and enabling file or remote-storage operations.
Before version 0.2.7, RClone Manager starts a local rclone remote-control service without authentication and permits cross-origin requests from any origin. A malicious web page opened while the service is running may use the user's browser to access the local API with the user's operating-system privileges, exposing credentials and enabling file or remote-storage operations.
Affected context
The issue affects RClone Manager deployments that start the local rclone rcd service with authentication disabled, broad cross-origin access enabled, and serving functionality exposed. Risk is present when a user browses to a malicious or compromised web page while the local daemon is active and the API is reachable on the loopback interface.
The issue affects RClone Manager deployments that start the local rclone rcd service with authentication disabled, broad cross-origin access enabled, and serving functionality exposed. Risk is present when a user browses to a malicious or compromised web page while the local daemon is active and the API is reachable on the loopback interface.
Exploit preconditions
- Attack surface: The local rclone remote-control API bound to 127.0.0.1:51900
- Required access: A user must open a malicious or compromised web page while the daemon is running
- Trigger point: The page sends cross-origin requests to the local unauthenticated API
- Why exploitation is possible: The service accepts requests without authentication and permits requests from arbitrary origins, allowing the browser to act against the API with the user's local privileges
- Attack surface: The local rclone remote-control API bound to 127.0.0.1:51900
- Required access: A user must open a malicious or compromised web page while the daemon is running
- Trigger point: The page sends cross-origin requests to the local unauthenticated API
- Why exploitation is possible: The service accepts requests without authentication and permits requests from arbitrary origins, allowing the browser to act against the API with the user's local privileges
Why this happens
The underlying issue is missing authentication on a security-sensitive local management interface, corresponding to CWE-306: Missing Authentication for Critical Function. The service is exposed with authentication disabled and permissive cross-origin policy, so possession of a user's browser context can become sufficient to invoke operations that should require explicit authorization. Binding to localhost does not by itself prevent access by web content when cross-origin protections are relaxed.
The underlying issue is missing authentication on a security-sensitive local management interface, corresponding to CWE-306: Missing Authentication for Critical Function. The service is exposed with authentication disabled and permissive cross-origin policy, so possession of a user's browser context can become sufficient to invoke operations that should require explicit authorization. Binding to localhost does not by itself prevent access by web content when cross-origin protections are relaxed.
Potential impact
- Configured storage credentials may be disclosed
- Locally accessible files may be read, uploaded, modified, or exfiltrated
- Files available through configured remotes may be accessed or changed
- Cloud or network storage data may be altered or deleted
- The user's storage accounts and associated data may be compromised
- Additional command-execution impact remains unconfirmed by the advisory
- Configured storage credentials may be disclosed
- Locally accessible files may be read, uploaded, modified, or exfiltrated
- Files available through configured remotes may be accessed or changed
- Cloud or network storage data may be altered or deleted
- The user's storage accounts and associated data may be compromised
- Additional command-execution impact remains unconfirmed by the advisory
General mitigation guidance
Mitigation generally focuses on protecting local administration APIs with authentication, authorization, and restrictive browser-origin policies.
Common defensive patterns include:
- Require strong authentication and authorization for every sensitive API operation
- Disable broad cross-origin access and allow only explicitly trusted origins where cross-origin use is necessary
- Avoid exposing serving or file-management functions through an unauthenticated control interface
- Bind services to the narrowest practical interface and restrict access with host or application-level policy
- Use least-privilege operating-system accounts and narrowly scoped remote credentials
- Apply read-only or limited-permission access for remotes when write access is not required
- Require explicit user confirmation for destructive or credential-revealing actions
Mitigation generally focuses on protecting local administration APIs with authentication, authorization, and restrictive browser-origin policies.
Common defensive patterns include:
- Require strong authentication and authorization for every sensitive API operation
- Disable broad cross-origin access and allow only explicitly trusted origins where cross-origin use is necessary
- Avoid exposing serving or file-management functions through an unauthenticated control interface
- Bind services to the narrowest practical interface and restrict access with host or application-level policy
- Use least-privilege operating-system accounts and narrowly scoped remote credentials
- Apply read-only or limited-permission access for remotes when write access is not required
- Require explicit user confirmation for destructive or credential-revealing actions
How teams detect issues like this
Organizations can look for local management services configured without authentication, wildcard origin policies, or file-serving capabilities.
Useful approaches include:
- Static analysis and configuration checks for disabled authentication flags and wildcard CORS settings
- Code review searches for local HTTP APIs that expose sensitive operations without authorization
- Runtime inventory of loopback listeners and their exposed endpoints
- Browser and endpoint telemetry identifying web pages making requests to local administration ports
- Policy enforcement that rejects unauthenticated control interfaces handling credentials or file operations
- Automated security review tools that flag missing authentication and permissive cross-origin configuration
Organizations can look for local management services configured without authentication, wildcard origin policies, or file-serving capabilities.
Useful approaches include:
- Static analysis and configuration checks for disabled authentication flags and wildcard CORS settings
- Code review searches for local HTTP APIs that expose sensitive operations without authorization
- Runtime inventory of loopback listeners and their exposed endpoints
- Browser and endpoint telemetry identifying web pages making requests to local administration ports
- Policy enforcement that rejects unauthenticated control interfaces handling credentials or file operations
- Automated security review tools that flag missing authentication and permissive cross-origin configuration
