CVE-2006-1126 in Gallery
Summary
by MITRE
Gallery 2 up to 2.0.2 allows remote attackers to spoof their IP address via a modified X-Forwarded-For (X_FORWARDED_FOR) HTTP header, which is checked by Gallery before other more reliable sources of IP address information, such as REMOTE_ADDR.
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Analysis
by VulDB Data Team • 04/21/2019
The vulnerability identified as CVE-2006-1126 affects Gallery 2 versions up to 2.0.2, representing a significant security flaw in web application input validation and trust model implementation. This issue demonstrates a classic case of improper input sanitization where the application fails to properly validate and prioritize IP address sources, creating an avenue for malicious actors to manipulate their network identity. The vulnerability specifically targets the application's handling of HTTP headers, particularly the X-Forwarded-For header, which is commonly used in web environments where applications operate behind load balancers or proxy servers. When Gallery 2 processes incoming requests, it incorrectly prioritizes the X-Forwarded-For header over more reliable sources like REMOTE_ADDR, which is set by the web server itself and represents the actual client IP address. This design flaw creates a trust relationship that can be easily abused by attackers who modify the X-Forwarded-For header to appear as if they are connecting from a different IP address.
The technical exploitation of this vulnerability involves crafting malicious HTTP requests with modified X-Forwarded-For headers that contain false IP address information. Since Gallery 2 processes this header before considering other more reliable IP sources, the application accepts the forged information as legitimate, allowing attackers to bypass IP-based access controls, logging mechanisms, and potentially security restrictions that should be applied based on the actual client address. This type of vulnerability falls under CWE-284, which addresses improper access control, and more specifically relates to CWE-285, which covers improper authorization. The flaw represents a fundamental misunderstanding of how to properly handle network information in applications that operate in complex network topologies, where multiple layers of network infrastructure can obscure the true source of requests.
The operational impact of this vulnerability extends beyond simple IP spoofing, as it can enable attackers to circumvent various security measures that rely on IP-based restrictions. Security administrators who have configured access controls, rate limiting, or logging based on IP addresses may find these protections ineffective against an attacker who can manipulate the X-Forwarded-For header. The vulnerability also affects audit trails and security monitoring systems that depend on accurate IP address information for identifying suspicious activities or potential breaches. Attackers could potentially use this flaw to bypass geographic restrictions, avoid IP-based blacklists, or conduct attacks while appearing to originate from trusted IP addresses, making detection and attribution significantly more difficult. This issue aligns with ATT&CK technique T1071.004, which covers application layer protocol: dns, as it represents a manipulation of application-level network information that can be used to evade network-based security controls.
The recommended mitigation for CVE-2006-1126 involves implementing proper validation and prioritization of IP address sources within the application. Security practitioners should ensure that applications verify the authenticity of forwarded headers and either reject or properly validate them before accepting them as legitimate IP address information. The most effective approach is to configure applications to trust only specific proxy servers and validate that forwarded headers come from known, trusted sources. Additionally, applications should be designed to prioritize system-level IP address information over HTTP headers, ensuring that REMOTE_ADDR or similar server-provided information takes precedence over user-supplied headers. Organizations should also implement proper input validation and sanitization procedures, including validating the format and content of forwarded headers, and establishing clear policies for handling HTTP headers in applications that operate in proxy or load-balanced environments. This vulnerability underscores the critical importance of secure coding practices and proper network architecture design when developing applications that must operate in complex network environments where multiple layers of infrastructure can affect how network information is presented to applications.