CVE-2013-7351 in Shaarli
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in index.php in Shaarli allow remote attackers to inject arbitrary web script or HTML via the URL to the (1) showRSS, (2) showATOM, or (3) showDailyRSS function; a (4) file name to the importFile function; or (5) vectors related to bookmarks.
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Analysis
by VulDB Data Team • 04/21/2023
The vulnerability CVE-2013-7351 represents a critical cross-site scripting flaw discovered in Shaarli's index.php file, a popular bookmarking application that allows users to store and share web links. This vulnerability affects multiple functions within the application and demonstrates a fundamental failure in input validation and output sanitization that exposes users to malicious web script injection attacks. The flaw specifically targets the showRSS, showATOM, and showDailyRSS functions, which are responsible for generating various feed formats for bookmark sharing and the importFile function that handles file uploads. The vulnerability's impact extends beyond simple data theft as it provides attackers with the capability to execute arbitrary scripts in the context of affected users' browsers, potentially leading to session hijacking, credential theft, or further exploitation of the compromised systems.
The technical implementation of this vulnerability stems from inadequate sanitization of user-supplied input across multiple attack vectors within the Shaarli application. When users access the RSS, ATOM, or daily RSS feed generation functions, the application fails to properly escape or validate the URL parameters passed to these functions, creating opportunities for attackers to inject malicious scripts that execute when other users view these feeds. Additionally, the importFile function lacks proper validation of file names, allowing malicious actors to upload files with script-containing names that could be executed when the application processes these imports. The bookmark-related vectors represent a particularly dangerous aspect of this vulnerability as they demonstrate how the flaw extends throughout the application's core functionality, affecting not just feed generation but also the fundamental bookmark management capabilities that users rely upon for secure information sharing.
The operational impact of CVE-2013-7351 extends far beyond simple data integrity concerns, as it fundamentally undermines the security model of the Shaarli application and the trust users place in the system for secure bookmark sharing. Attackers can exploit these vulnerabilities to inject malicious scripts that persistently compromise user sessions, potentially leading to unauthorized access to personal bookmark collections, credential theft, or even complete account takeover scenarios. The vulnerability's presence in feed generation functions means that any user who views these feeds, whether through direct access or automated feed readers, becomes a potential victim of the injected malicious code. This creates a wide attack surface where a single compromised bookmark or feed can propagate malicious content to multiple users within the Shaarli community. The persistence of these vulnerabilities across different functions also indicates a systemic issue in the application's security architecture, suggesting that similar flaws may exist in other areas of the codebase that require comprehensive security auditing and remediation.
The vulnerability aligns with CWE-79, which describes Cross-Site Scripting flaws in web applications, and demonstrates characteristics consistent with the attack patterns documented in the MITRE ATT&CK framework under the T1566 technique for Phishing and T1059 for Command and Scripting Interpreter. Organizations using Shaarli or similar bookmarking applications must implement immediate mitigations including input validation, output encoding, and proper sanitization of all user-supplied data. The recommended approach involves implementing strict input validation for all parameters passed to the vulnerable functions, implementing proper HTML escaping for all dynamic content, and conducting comprehensive code reviews to identify and address similar vulnerabilities throughout the application. Additionally, users should be educated about the risks of bookmarking untrusted links and the importance of maintaining updated software versions to protect against known vulnerabilities. The incident highlights the critical importance of security testing and validation in web applications, particularly those handling user-generated content and sharing features that are inherently prone to injection attacks.