CVE-2012-2566 in Web Filtering
Summary
by MITRE
Bloxx Web Filtering before 5.0.14 does not properly interpret X-Forwarded-For headers during access-control and logging operations for HTTPS connection attempts, which allows remote attackers to bypass intended IP address and domain restrictions, and trigger misleading log entries, via a crafted header.
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Analysis
by VulDB Data Team • 08/10/2024
The vulnerability identified as CVE-2012-2566 affects Bloxx Web Filtering software versions prior to 5.0.14, specifically targeting the improper handling of X-Forwarded-For headers during secure HTTPS connection operations. This weakness stems from the application's failure to correctly validate and process the X-Forwarded-For HTTP header, which is commonly used to identify the original IP address of a client connecting through an HTTP proxy or load balancer. The flaw exists in the access-control and logging mechanisms that govern HTTPS connection attempts, creating a significant security gap that adversaries can exploit to circumvent intended network restrictions.
The technical implementation of this vulnerability resides in the application's trust model for X-Forwarded-For headers, which are typically used to preserve client IP information when requests pass through multiple proxies. In the affected Bloxx versions, the software does not properly sanitize or validate these headers, allowing attackers to inject malicious IP addresses that bypass IP-based access controls. This misinterpretation occurs during the HTTPS connection process where the application relies on the X-Forwarded-For header to determine client identity for access control decisions. The flaw essentially permits attackers to spoof their IP addresses and gain unauthorized access to restricted resources or services that should only be accessible from specific network locations.
The operational impact of this vulnerability extends beyond simple access bypass to include potential data integrity compromise through misleading log entries. When attackers manipulate X-Forwarded-For headers, they can create false audit trails that obscure the true origin of malicious activities, making forensic analysis and security monitoring significantly more difficult. This manipulation affects both the access control enforcement and the logging infrastructure, potentially allowing unauthorized users to access restricted domains or content while the system's logs appear to show legitimate access patterns. The vulnerability particularly affects organizations relying on IP-based restrictions for web filtering, content control, or access management, as it undermines the fundamental security assumptions built into their network access policies.
Organizations should implement immediate mitigations including updating to Bloxx Web Filtering version 5.0.14 or later, which contains the necessary fixes for proper X-Forwarded-For header handling. Network administrators should also configure additional security controls such as implementing strict header validation policies, deploying web application firewalls with X-Forwarded-For validation capabilities, and establishing more robust logging mechanisms that can detect header manipulation attempts. The vulnerability aligns with CWE-284, which describes improper access control, and represents a specific instance of insecure input handling where the application fails to properly validate user-supplied data. From an ATT&CK perspective, this weakness maps to privilege escalation and defense evasion techniques, as attackers can bypass access controls and manipulate audit trails to avoid detection. Additionally, organizations should consider implementing network segmentation and multi-factor authentication controls to provide defense-in-depth against similar vulnerabilities that may exist in other components of their web filtering infrastructure.