CVE-2017-14038 in CrushFTP
Summary
by MITRE
CrushFTP before 7.8.0 and 8.x before 8.2.0 has a redirect vulnerability.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 11/12/2019
CrushFTP versions prior to 7.8.0 and 8.x prior to 8.2.0 contain a redirect vulnerability that allows unauthorized redirection of users to malicious websites. This vulnerability stems from insufficient validation of redirect URLs within the application's authentication and session management mechanisms. The flaw enables attackers to craft specially formatted URLs that would redirect users to phishing sites or malicious domains when they attempt to access the FTP service. The vulnerability affects the application's ability to properly sanitize user input during authentication flows and session handling processes. Security researchers identified that the application fails to validate the scheme and domain of redirect URLs, allowing attackers to manipulate the redirect behavior by injecting crafted URLs. This issue falls under the category of insecure redirection as defined by CWE-601, which specifically addresses the risk of open redirect vulnerabilities. The vulnerability can be exploited by malicious actors to conduct phishing attacks, steal credentials, or deliver malware to unsuspecting users who believe they are accessing legitimate FTP services. The impact extends beyond simple redirection as it can facilitate more sophisticated attacks including credential harvesting and session hijacking.
The technical implementation of this vulnerability occurs within the application's URL parsing and validation logic. When users attempt to authenticate or navigate through the FTP interface, the system processes redirect parameters without adequate sanitization of the target URL. Attackers can exploit this by crafting URLs that contain malicious domains in the redirect parameter, causing the application to redirect users to attacker-controlled websites. The vulnerability exists because the application does not properly validate whether the redirect URL belongs to the same domain or has been explicitly allowed by the system configuration. This weakness is particularly dangerous because it can be leveraged in conjunction with social engineering techniques to make the malicious redirection appear legitimate to users. The vulnerability is classified under attack technique T1566 in the MITRE ATT&CK framework, which covers phishing and social engineering attacks that leverage web-based redirections. The flaw is particularly concerning in enterprise environments where FTP services are commonly used for file transfers and where users may not be trained to recognize suspicious redirects.
Organizations using affected CrushFTP versions should immediately implement mitigation strategies to address this vulnerability. The primary recommendation is to upgrade to CrushFTP version 7.8.0 or 8.2.0, which contain proper URL validation and sanitization mechanisms. Administrators should also implement additional network-level controls such as web application firewalls that can detect and block suspicious redirect patterns. The application should be configured to only allow redirects to pre-approved domains or implement strict URL validation that ensures all redirect destinations are within the trusted domain boundaries. Security teams should monitor access logs for unusual redirect patterns that may indicate exploitation attempts. Network segmentation and access controls should be implemented to limit exposure of the FTP service to internal networks only. Organizations should also conduct security awareness training for users to help them recognize suspicious redirects and phishing attempts. The vulnerability demonstrates the importance of proper input validation and the principle of least privilege in web application security. Additional mitigations include implementing secure coding practices that validate all user-supplied input, particularly redirect parameters, and ensuring that applications follow secure redirect implementation guidelines. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other applications within the organization's attack surface.