Gitea Open Redirect Scanner

Gitea is a lightweight and fully customizable self-hosted Git service, used by developers and organizations worldwide for version control. This platform mimics core features of GitHub, offering both public and private repositories for collaborative software projects. With its simplicity, it's particularly favored by smaller teams and hobbyist developers who require a private development environment without the overhead of more substantial enterprise solutions. Gitea supports multiple operating systems such as Linux, Windows, and macOS, and comes equipped with several collaborative features, including issue tracking, code review, built-in wiki, and continuous integration support. It is often deployed on premises to augment an organization's software lifecycle processes, providing a cost-effective alternative to cloud-based applications. Regular updates and community contributions ensure feature enhancements and security patches are maintained.

An open redirect vulnerability exists in Gitea versions prior to 1.21.0, allowing an attacker to craft URLs that redirect unsuspecting users to malicious sites. This vulnerability occurs via the "redirect_to" parameter within the login process, creating a possibility for phishing by redirecting users to external websites post authentication. Attackers can exploit this flaw to guide users away from trusted domains, potentially capturing sensitive credentials or personal details. The open redirect weakness arises from insufficient validation of where users are redirected post-login, failing to restrict redirects to internal URLs only. Upon redirecting to the external site, threats such as exploit kits or devious web pages can attempt to deceive users. Correcting this issue involves adequate validation of URLs used in redirection processes.

The open redirect vulnerability targets the login endpoint /user/login, utilizing improper sanitization of redirect_to parameter values. Attackers manipulate this parameter by inserting URL traversal sequences, which Gitea's backend does not adequately validate or restrict. Payloads constructed as such compel the application to redirect authenticated users to potentially harmful domains, leveraging regular expressions in headers to detect improper URL formation. The HTTP 302 response code is indicative of a successful redirection, validating the presence of this vulnerability. Gitea's lack of robust input validation permits the crafting of URLs that trick the application into redirecting users to unintended and possibly malicious locations. These issues stem from overlooking essential security checks in the interface inputs, creating exploitable entry points for unauthorized redirection.

If exploited, this vulnerability can divert users to harmful websites, enabling attackers to execute phishing attacks or capture credentials. Impacted users are led to believe they are interacting with legitimate elements of the application while unknowingly entering details on fake portals. Successful exploitation can facilitate the dissemination of malware, install malicious software, or collect users' private data under false pretenses. Such consequences pose significant risks for end-users and organizations alike, damaging reputations and trust. Exposure to open redirects also makes Gitea installations attractive targets for malicious actors seeking to exploit trust relationships between users and the application. Immediate mitigation measures must be implemented to prevent exploitation and safeguard user data integrity.

REFERENCES

• https://github.com/go-gitea/gitea/issues/36660