CVE-2016-9500 in FTP Server
Summary
by MITRE
Accellion FTP server prior to version FTA_9_12_220 uses the Accusoft Prizm Content flash component, which contains multiple parameters (customTabCategoryName, customButton1Image) that are vulnerable to cross-site scripting.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 12/27/2024
The Accellion FTP server vulnerability CVE-2016-9500 represents a critical cross-site scripting flaw within the Prizm Content flash component used by the software. This vulnerability affects versions prior to FTA_9_12_220 and specifically targets two parameters: customTabCategoryName and customButton1Image, which are susceptible to malicious input injection. The flaw resides in the server's web interface implementation where user-supplied data is not properly sanitized before being rendered in the browser context. This allows attackers to inject malicious javascript code through these parameters, potentially compromising user sessions and executing unauthorized actions on behalf of authenticated users. The vulnerability demonstrates a classic lack of input validation and output encoding practices that are fundamental to preventing XSS attacks.
The technical exploitation of this vulnerability follows established patterns documented in CWE-79, which classifies cross-site scripting as a weakness where untrusted data is incorporated into web page content without proper sanitization. Attackers can craft malicious payloads that leverage these vulnerable parameters to inject javascript code into the Prizm Content flash component's rendering process. When legitimate users view pages containing the malicious input, the injected code executes within their browser context, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The attack vector operates through the web interface where the parameters are processed and displayed, making it accessible to remote attackers without requiring privileged access to the system. This aligns with ATT&CK technique T1566.001 which describes spearphishing with malicious attachments, as the vulnerability could be exploited through crafted web content.
The operational impact of this vulnerability extends beyond simple script execution to encompass potential privilege escalation and data compromise within the Accellion FTP environment. Since the affected system handles sensitive file transfers and document management, successful exploitation could enable attackers to access confidential data, modify file transfer configurations, or establish persistent access points within the network. The vulnerability affects the server's web-based management interface, potentially allowing attackers to manipulate the content rendering system and gain unauthorized access to the underlying file storage mechanisms. Organizations using vulnerable versions face significant risk of data breaches and unauthorized system access, particularly in environments where the FTP server manages critical business documents or sensitive information. The vulnerability's presence in the flash component also indicates potential issues with third-party library security practices and the importance of regular security assessments of integrated components.
Mitigation strategies for CVE-2016-9500 should prioritize immediate patching to version FTA_9_12_220 or later, which addresses the vulnerable Prizm Content flash component. Organizations should implement comprehensive input validation and output encoding measures to prevent similar vulnerabilities in other web applications, following security best practices outlined in OWASP Top 10 and NIST guidelines. Network segmentation and access controls should be strengthened to limit exposure of the vulnerable FTP server interface. Regular security assessments of third-party components and continuous monitoring for similar vulnerabilities in integrated systems are essential. Additionally, implementing content security policies and disabling unnecessary flash components can reduce the attack surface and prevent exploitation of similar XSS vulnerabilities in the future. Security teams should conduct thorough vulnerability assessments to identify other potentially affected components and ensure proper security configurations are in place across all web-facing applications.