CVE-2005-2729 in Security Linux
Summary
by MITRE
The HTTP proxy in Astaro Security Linux 6.0 does not properly filter HTTP CONNECT requests to localhost, which allows remote attackers to bypass firewall rules and connect to local services.
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Analysis
by VulDB Data Team • 01/01/2025
The vulnerability identified as CVE-2005-2729 represents a critical security flaw in the HTTP proxy implementation of Astaro Security Linux 6.0 operating system. This issue stems from inadequate validation of HTTP CONNECT requests that are processed through the proxy server, creating a pathway for malicious actors to circumvent established network security controls. The vulnerability specifically targets the proxy's handling of requests directed toward localhost addresses, which are typically restricted to prevent unauthorized access to internal network services. This flaw enables remote attackers to establish connections to services that should remain isolated within the local network environment, effectively undermining the fundamental purpose of firewall protection mechanisms.
The technical root cause of this vulnerability lies in the improper filtering of HTTP CONNECT requests that attempt to access localhost destinations. When a client makes a CONNECT request to the proxy server, the system should validate the target address and enforce appropriate access controls based on the organization's security policies. However, the Astaro Security Linux 6.0 proxy implementation fails to properly validate these requests, allowing unauthorized connections to local services that are typically protected by firewall rules. This represents a classic case of insufficient input validation and access control enforcement, which aligns with CWE-284 Access Control Issues and specifically manifests as a failure to properly filter network traffic based on destination addresses. The vulnerability occurs at the application layer of the network stack, where the proxy server should act as a security gateway but instead becomes a vector for privilege escalation and unauthorized access.
The operational impact of this vulnerability is severe and multifaceted, as it allows remote attackers to bypass multiple layers of network security that are designed to protect internal services from external access. Attackers can exploit this weakness to gain access to sensitive local services such as database servers, administrative interfaces, or other internal systems that should only be accessible from within the trusted network perimeter. This capability enables a range of malicious activities including data exfiltration, system compromise, and further lateral movement within the network. The vulnerability is particularly dangerous because it operates at the network boundary where the proxy server sits, meaning that successful exploitation can provide attackers with a foothold that allows them to access services that are normally protected by the organization's internal firewall rules. This creates a significant risk for organizations that rely on the proxy server as a security control to separate their internal network from external threats.
Organizations affected by this vulnerability should implement immediate mitigations to address the security gap in their Astaro Security Linux 6.0 deployments. The primary recommendation involves updating to a patched version of the Astaro Security Linux software that properly validates HTTP CONNECT requests and enforces appropriate access controls for localhost destinations. Additionally, network administrators should consider implementing additional filtering rules at the network level to prevent unauthorized access to localhost services, even when the proxy server is properly configured. The mitigation strategy should also include monitoring network traffic for suspicious CONNECT requests and implementing logging mechanisms to detect potential exploitation attempts. From a cybersecurity perspective, this vulnerability demonstrates the importance of proper access control implementation and the need for thorough security testing of network infrastructure components. The issue aligns with ATT&CK technique T1071.001 Application Layer Protocol: Web Protocols, where attackers exploit proxy server configurations to gain unauthorized access to internal resources, and represents a clear example of how proxy server misconfigurations can create significant security risks that undermine enterprise security posture.