A flaw has been found in go-sonic sonic up to 1.1.4. The affected element is the function FetchTheme of the file service/theme/git_fetcher.go of the component Theme Fetching API. Executing manipulation of the argument uri can lead to server-side request forgery. The attack may be launched remotely. The exploit has been published and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
go-sonic sonic versions up to 1.1.4 are vulnerable to a Server-Side Request Forgery (SSRF) attack. This allows attackers to make unauthorized requests from the server, potentially leading to sensitive data exposure or internal network compromise. The vulnerability is easily exploitable due to a published proof-of-concept and lack of vendor response.
Step 1: Payload Delivery: The attacker crafts a malicious URI, such as http://internal-service:8080/sensitive-data or file:///etc/passwd, and submits it as the uri argument to the FetchTheme function.
Step 2: Request Execution: The FetchTheme function, without proper validation, uses the attacker-controlled URI to initiate an HTTP request.
Step 3: Data Retrieval/Interaction: The server, acting on behalf of the attacker, makes the request to the specified URI. This could be an internal service, a local file, or an external server.
Step 4: Information Leakage/Exploitation: The response from the target (internal service, file, etc.) is then either returned to the attacker (in the case of an external server) or, if the attacker can control the response, used to further exploit the system. This could lead to data exfiltration, service disruption, or further compromise.
The vulnerability lies within the FetchTheme function in service/theme/git_fetcher.go. This function, part of the Theme Fetching API, is responsible for retrieving themes from a specified URI. The root cause is a lack of proper input validation and sanitization of the uri argument. Specifically, the function fails to validate the destination of the URI, allowing an attacker to specify an internal or external address. This allows an attacker to control the destination of the HTTP request made by the server. This can be exploited to access internal services, bypass firewall restrictions, or potentially leak sensitive information.