CVE-2016-4807 in Web2py
Summary
by MITRE
Web2py versions 2.14.5 and below was affected by Reflected XSS vulnerability, which allows an attacker to perform an XSS attack on logged in user (admin).
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Analysis
by VulDB Data Team • 06/24/2024
The vulnerability identified as CVE-2016-4807 affects Web2py web application framework versions 2.14.5 and earlier, representing a critical reflected cross-site scripting flaw that specifically targets authenticated administrator users. This vulnerability resides in the framework's handling of user input within HTTP request parameters, creating an attack vector that can be exploited by malicious actors to inject malicious scripts into web pages viewed by administrators. The flaw occurs when the application fails to properly sanitize or escape user-supplied data before incorporating it into dynamically generated web content, allowing attackers to craft malicious URLs that, when visited by administrators, execute unauthorized scripts within the admin context.
The technical implementation of this reflected XSS vulnerability stems from inadequate input validation and output encoding mechanisms within Web2py's core request processing pipeline. When administrators navigate to specifically crafted URLs containing malicious script payloads, the framework processes these parameters without sufficient sanitization, resulting in the injection of executable JavaScript code into the admin user's browser session. This creates a persistent threat vector where attackers can leverage the elevated privileges of admin accounts to perform unauthorized actions, including but not limited to accessing sensitive data, modifying application configurations, or establishing persistent backdoors within the web application environment. The vulnerability specifically impacts authenticated sessions where administrative privileges are active, making the potential attack surface particularly dangerous due to the elevated access rights available to administrators.
The operational impact of CVE-2016-4807 extends beyond simple script injection, as it enables attackers to exploit the administrative session to gain full control over the web application and potentially the underlying system. This vulnerability aligns with CWE-79 which categorizes cross-site scripting flaws as weaknesses in input validation and output encoding, and can be mapped to ATT&CK technique T1566.001 which covers social engineering through spearphishing with a link. The reflected nature of this vulnerability means that attackers must convince administrators to click on malicious links, typically through phishing campaigns or compromised legitimate web resources. Successful exploitation could result in complete system compromise, data breaches, and unauthorized modification of web application content, with the attack being particularly effective against organizations that rely heavily on Web2py for critical business applications.
Mitigation strategies for CVE-2016-4807 should prioritize immediate patching of affected Web2py installations to version 2.14.6 or later, which contains the necessary security fixes. Organizations should implement comprehensive input validation at multiple layers of their application architecture, including parameter validation, content sanitization, and output encoding mechanisms. Network-based defenses such as web application firewalls can provide additional protection by monitoring for suspicious URL patterns and blocking known malicious payloads. Regular security auditing and penetration testing should be conducted to identify similar vulnerabilities in custom application code built on top of the Web2py framework. The implementation of Content Security Policy headers and proper HTTP response headers can provide additional defense-in-depth measures to prevent script execution even if input validation fails. Security awareness training for administrators should also be implemented to reduce the risk of successful social engineering attacks that exploit this vulnerability, as the reflected nature of the attack requires user interaction with malicious links.