CVE-2018-16832 in xunfeng
Summary
by MITRE
CSRF in the anti-csrf decorator in xunfeng 0.2.0 allows an attacker to modify the configuration via a Flash file because views/lib/AntiCSRF.py can overwrite the request.host value with the content of the X-Forwarded-Host HTTP header.
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Analysis
by VulDB Data Team • 05/08/2023
The vulnerability identified as CVE-2018-16832 represents a critical cross-site request forgery weakness within the xunfeng web application framework version 0.2.0. This flaw specifically resides in the anti-csrf decorator implementation located in views/lib/AntiCSRF.py, where the framework fails to properly validate or sanitize the X-Forwarded-Host HTTP header. The issue stems from the framework's insecure handling of reverse proxy configurations, where an attacker can manipulate the request.host value through malicious Flash content, effectively bypassing the intended security controls. This vulnerability directly violates the principle of least privilege and demonstrates a dangerous trust assumption in HTTP header values that should typically be validated against known safe sources.
The technical exploitation of this vulnerability occurs through manipulation of the X-Forwarded-Host header within Flash-based attacks, which allows an attacker to inject arbitrary host values into the application's request processing pipeline. When the anti-csrf decorator processes requests, it blindly accepts and overwrites the legitimate request.host value with content from the X-Forwarded-Host header without proper validation. This creates a scenario where an attacker can forge requests that appear to originate from trusted hosts, effectively circumventing the csrf protection mechanisms. The flaw is classified as a CWE-346: Improper Verification of Source of a Communication Channel, which specifically addresses the failure to properly validate the authenticity of communication sources in web applications. This weakness enables attackers to perform unauthorized configuration modifications that could lead to complete system compromise.
The operational impact of this vulnerability extends beyond simple csrf attacks to include configuration manipulation and potential privilege escalation within the application. An attacker who successfully exploits this vulnerability can modify critical application settings, alter user permissions, or redirect traffic to malicious endpoints through the manipulated host value. The attack surface is particularly concerning because it leverages Flash content, which was historically widely supported and often used in enterprise environments, making the exploitation vector more accessible. This vulnerability aligns with ATT&CK technique T1071.004: Application Layer Protocol: DNS, where attackers manipulate application behavior through header injection, and T1566.002: Phishing: Spearphishing Attachment, where malicious Flash files serve as initial attack vectors. The potential for persistent exploitation increases when the application relies on reverse proxies, as the vulnerability can be maintained across multiple requests if the malicious header persists.
Mitigation strategies for CVE-2018-16832 require immediate implementation of header validation controls within the AntiCSRF.py decorator. The framework should enforce strict validation of the X-Forwarded-Host header by verifying its content against a predefined whitelist of trusted proxy servers or by implementing proper header sanitization that strips or validates the header content before processing. Organizations should also implement network-level controls to prevent unauthorized modification of HTTP headers, particularly in environments where multiple proxy servers are involved. The solution must include proper input validation and sanitization techniques that align with OWASP Top Ten security requirements, specifically addressing the prevention of header injection attacks. Additionally, implementing proper logging and monitoring of header changes can help detect potential exploitation attempts. Security teams should conduct comprehensive code reviews to identify similar patterns in other components and ensure that all HTTP header processing follows secure coding practices that prevent trust assumptions based on unvalidated external inputs, thereby protecting against both current and potential future variants of this class of vulnerability.