CVE-2009-0804 in Ziproxy
Summary
by MITRE
Ziproxy 2.6.0, when transparent interception mode is enabled, uses the HTTP Host header to determine the remote endpoint, which allows remote attackers to bypass access controls for Flash, Java, Silverlight, and probably other technologies, and possibly communicate with restricted intranet sites, via a crafted web page that causes a client to send HTTP requests with a modified Host header.
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Analysis
by VulDB Data Team • 07/26/2024
Ziproxy version 260 operates as an HTTP proxy server that can function in transparent interception mode, where it intercepts and processes HTTP traffic without requiring client configuration changes. The vulnerability stems from the proxy's reliance on the HTTP Host header to determine the target endpoint for forwarded requests. When transparent mode is enabled, the proxy examines the Host header value from incoming requests to route traffic to the appropriate destination server. This design flaw creates a significant security gap because the Host header is easily manipulated by remote attackers who can craft malicious web pages that send HTTP requests with modified Host header values.
The technical implementation of this vulnerability allows attackers to bypass access controls that would normally restrict client access to specific resources or intranet services. By crafting HTTP requests with manipulated Host headers, malicious actors can cause the proxy to forward requests to internal systems or services that should otherwise be restricted from external access. This occurs because the proxy trusts the Host header value without proper validation or authentication checks, effectively creating a path for unauthorized access to internal network resources that are typically protected by firewalls or other access control mechanisms. The vulnerability specifically impacts Flash, Java, and Silverlight applications, which often make cross-domain requests that can be exploited through this mechanism.
The operational impact of this vulnerability extends beyond simple access bypass to potentially enable more sophisticated attacks including internal network reconnaissance and lateral movement. Attackers can leverage this weakness to access restricted intranet sites, potentially discovering sensitive internal services or systems that should remain isolated from external networks. The vulnerability affects multiple technologies because they all rely on HTTP communication patterns that can be manipulated through Host header modification, creating a broad attack surface that spans various client-side applications. This weakness represents a critical failure in the proxy's trust model, where it assumes that the Host header contains valid routing information without proper verification.
Security mitigations for this vulnerability should focus on implementing strict validation of Host header values and establishing proper access controls within the proxy configuration. Organizations should disable transparent interception mode when not strictly required, or implement additional authentication and authorization checks before forwarding requests to remote endpoints. The proxy should validate that Host header values correspond to legitimate external domains or implement strict whitelisting of allowed destinations. This vulnerability aligns with CWE-285 which addresses improper authorization in access control systems, and maps to ATT&CK technique T1071001 for application layer protocol usage. Network segmentation and firewall rules should also be implemented to limit direct access to internal services, while regular security assessments should verify that proxy configurations properly enforce access control policies. The vulnerability demonstrates the importance of proper input validation and the principle of least privilege in network security implementations.