CVE-2015-2989 in PHP Twit BBS
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in index.php in LEMON-S PHP Twit BBS allows remote attackers to inject arbitrary web script or HTML via the imagetitle parameter.
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Analysis
by VulDB Data Team • 12/01/2017
The cross-site scripting vulnerability identified as CVE-2015-2989 exists within the LEMON-S PHP Twit BBS application, specifically in the index.php script where user input is not properly sanitized before being rendered in web pages. This flaw represents a classic client-side attack vector that enables malicious actors to execute arbitrary scripts in the context of other users' browsers. The vulnerability manifests through the imagetitle parameter which serves as an entry point for injecting malicious code that can be executed when other users view affected pages.
This vulnerability falls under CWE-79 which categorizes cross-site scripting flaws as weaknesses in input validation and output encoding. The technical implementation involves the application failing to properly escape or filter user-supplied data before incorporating it into dynamically generated HTML content. When the imagetitle parameter contains malicious script code such as javascript:alert(1) or embedded html tags, the application processes this input without adequate sanitization measures, allowing the injected code to execute in the victim's browser context. The vulnerability is particularly concerning because it operates at the presentation layer where user interactions directly influence rendered content, making it a prime target for exploitation in web-based attacks.
The operational impact of this vulnerability extends beyond simple script execution to potentially enable more sophisticated attacks including session hijacking, credential theft, and redirection to malicious sites. Attackers can leverage this flaw to create persistent malicious payloads that affect all users who view the compromised content, making it a significant threat to the application's integrity and user security. The vulnerability affects the application's ability to maintain secure user sessions and can compromise the trust relationship between users and the application. According to ATT&CK framework, this vulnerability maps to T1059.008 which covers the use of scripting languages for execution, and T1531 which involves the use of unauthorized commands to gain access to systems. The attack chain typically involves crafting malicious input in the imagetitle parameter, submitting it through the web interface, and then having other users inadvertently execute the injected code when viewing the affected content.
Mitigation strategies for this vulnerability require implementing proper input validation and output encoding mechanisms throughout the application. The most effective approach involves sanitizing all user-supplied input by removing or escaping special characters that could be interpreted as HTML or script tags. Implementing Content Security Policy headers can provide additional protection by restricting the sources from which scripts can be loaded. Regular security code reviews should focus on identifying all input vectors that could potentially lead to XSS vulnerabilities, with particular attention to parameters that directly influence HTML generation. The application should also implement proper HTTP headers including X-Content-Type-Options and X-Frame-Options to prevent certain types of attacks that could exploit the XSS vulnerability. Additionally, employing a web application firewall can provide an additional layer of protection by monitoring and filtering traffic for known malicious patterns associated with XSS attacks. Organizations should also consider implementing automated security testing tools that can scan for XSS vulnerabilities during the development lifecycle, ensuring that similar issues are identified and addressed before deployment to production environments.