Tiny Tiny RSS Open Redirect Scanner

Tiny Tiny RSS is a free web-based news feed (RSS/Atom) reader intended for use in personal content management systems, particularly beneficial for individuals or small organizations that prefer self-hosted alternatives to commercial online feed readers. It is primarily used by tech-savvy users who manage their own servers, providing a customizable and streamlined platform for aggregating and reading feeds. Its user base typically includes individuals who prioritize privacy and control over their data, opting for self-hosted solutions rather than relying on proprietary services. Tiny Tiny RSS is widely appreciated for its open-source nature, versatility across different operating systems, and its ability to be integrated with various third-party services for enhanced functionality. Its extensibility and active development community make it an attractive choice for users requiring detailed management over their RSS feeds. The platform is deployed by a global community, demonstrating its utility in varied contexts and technological landscapes.

Open Redirect vulnerabilities occur when a web application accepts user-controlled input in an HTTP parameter link and redirects the user to the specified link without sufficient validation. This vulnerability can be exploited to redirect users to malicious sites, spoof content, or in phishing attacks where a malicious actor could trick the end-user into following a link that appears to be reputable but redirects to a malicious site. The vulnerability is typically caused by inadequate input validation or parameter filtering in the application's code that handles redirects. Attackers can exploit open redirect vulnerabilities to execute advanced phishing attacks or in conjunction with other vulnerabilities for larger security breaches. Addressing this vulnerability involves ensuring all redirect URLs are validated against a whitelist of approved URLs or ensuring redirects occur only within the same domain.

The open redirect vulnerability in Tiny Tiny RSS is found within the `public.php` file, where the `return` parameter can be manipulated by attackers. The vulnerability arises because the application lacks effective validation or sanitization of user-inputted URL parameters, specifically concerning the `return` parameter. By crafting a URL that exploits the `return` parameter, an attacker can cause an unsuspecting user to be redirected to an attacker-controlled external URL, post-authentication. The vulnerable endpoint fails to validate the integrity and authenticity of the external URL to which redirection occurs, allowing for exploitation. Technical investigations reveal that this is due to insufficient checks in the server-side logic that processes redirect requests, leaving the software susceptible to manipulation. The exploitation does not require extensive privileges or direct user interaction, significantly reducing the attack effort from the adversary's perspective.

Exploiting this open redirect vulnerability could facilitate phishing attacks by redirecting users to fraudulent websites disguised as legitimate ones. Users might innocently follow the redirects while divulging sensitive data like credentials on malicious sites controlled by attackers. In the context of Tiny Tiny RSS, such redirects can also work in combination with social engineering tactics to further compromise user accounts. Additionally, this vulnerability could undermine user trust, degrade the integrity of the application, and result in reputational damage to organizations utilizing Tiny Tiny RSS. Security-wise, open redirect vulnerabilities might be leveraged to bypass security filters, channel users to download harmful content, or contribute to broader chains of security exploits against the system.

REFERENCES

• https://seclists.org/oss-sec/2019/q1/155