CVE-2005-4687 in Blog Cms
Summary
by MITRE
PunBB 1.2.9, used alone or with F-ART BLOG:CMS, may trust a client s IP address as specified in the X-Forwarded-For HTTP header rather than the TCP/IP stack, which allows remote attackers to misrepresent their IP address by sending a modified header.
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Analysis
by VulDB Data Team • 08/01/2017
The vulnerability described in CVE-2005-4687 represents a significant security flaw in PunBB 1.2.9 software that operates in conjunction with F-ART BLOG:CMS. This issue stems from the application's improper handling of HTTP headers, specifically the X-Forwarded-For header, which creates a dangerous trust relationship between the application and client-provided information. The vulnerability is categorized under CWE-284 Access Control Issues, as it allows unauthorized modification of access control mechanisms through manipulation of network metadata. When PunBB processes requests through a proxy or load balancer environment, it incorrectly prioritizes the client-specified IP address over the legitimate TCP/IP source address information provided by the network stack.
The technical implementation of this vulnerability occurs when the application receives HTTP requests through a web server or proxy configuration that forwards client IP addresses via the X-Forwarded-For header. Rather than validating or properly sanitizing this information, PunBB 1.2.9 accepts the forwarded IP address as authoritative, effectively allowing attackers to spoof their true network location. This misconfiguration enables remote attackers to manipulate the application's perception of their source IP address, which can have cascading effects on authentication, access control, and logging mechanisms. The flaw is particularly dangerous in multi-tiered network architectures where applications depend on proxy servers to handle client connections, as it bypasses fundamental network security assumptions.
The operational impact of this vulnerability extends beyond simple IP address spoofing and can enable sophisticated attack vectors including unauthorized access attempts, bypass of IP-based access controls, and manipulation of audit trails. Attackers can exploit this weakness to circumvent firewall rules that rely on IP address filtering, gain unauthorized access to restricted resources, or attempt to evade detection mechanisms that depend on accurate IP address logging. The vulnerability directly maps to ATT&CK technique T1071.004 Application Layer Protocol: DNS, as it involves manipulation of application-layer protocols to alter network behavior. Additionally, it relates to T1566 Credential Stuffing and T1078 Valid Accounts, since attackers can potentially use spoofed IP addresses to bypass account-based security controls or to make authentication attempts appear to originate from legitimate sources.
Mitigation strategies for CVE-2005-4687 require a multi-faceted approach addressing both application-level and infrastructure-level security controls. Organizations should implement proper header validation mechanisms that verify the authenticity of forwarded IP addresses through trusted proxy configurations or by requiring explicit header sanitization. The recommended solution involves configuring web servers to properly handle X-Forwarded-For headers by either removing them before processing or validating them against known trusted proxy IP addresses. This aligns with the principle of least privilege and proper input validation as outlined in OWASP Top Ten security practices. Additionally, implementing network-level controls such as IP address filtering, proper proxy configuration, and secure header handling can prevent attackers from exploiting this vulnerability. The vulnerability demonstrates the critical importance of not trusting client-provided information without proper validation, a fundamental principle in secure application development that is essential for maintaining the integrity of network security controls.