CVE-2009-2059 in Web Browser
Summary
by MITRE
Opera, possibly before 9.25, uses the HTTP Host header to determine the context of a document provided in a (1) 4xx or (2) 5xx CONNECT response from a proxy server, which allows man-in-the-middle attackers to execute arbitrary web script by modifying this CONNECT response, aka an "SSL tampering" attack.
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Analysis
by VulDB Data Team • 09/06/2019
The vulnerability described in CVE-2009-2059 represents a critical security flaw in Opera web browser versions prior to 9.25 that specifically affects how the browser handles HTTP CONNECT responses from proxy servers. This issue manifests when Opera receives 4xx or 5xx status codes during SSL tunneling operations, where the browser incorrectly relies on the Host header field from the proxy response to establish document context rather than properly validating the SSL connection integrity. The fundamental flaw lies in Opera's trust of proxy server responses without sufficient validation mechanisms, creating a dangerous attack surface that enables malicious actors to manipulate SSL connections through man-in-the-middle techniques.
The technical implementation of this vulnerability stems from Opera's improper handling of HTTP CONNECT responses during SSL proxy operations. When a web browser establishes an SSL connection through a proxy server, it typically uses the CONNECT method to request the proxy to establish a tunnel to the target server. In this scenario, Opera versions before 9.25 fail to properly validate the SSL certificate presented by the proxy server and instead trust the Host header field from the proxy's response to determine the context of the document. This approach creates a path for attackers to modify the CONNECT response, particularly when the proxy returns 4xx or 5xx status codes, allowing them to inject arbitrary web scripts into the browser context.
The operational impact of this vulnerability is severe and directly aligns with the ATT&CK framework's techniques for credential access and execution. Attackers can exploit this weakness to perform SSL tampering attacks that bypass normal security controls, potentially leading to session hijacking, data interception, and arbitrary code execution within the browser environment. The vulnerability specifically enables attackers to manipulate the SSL connection context by altering the proxy response, which could result in users unknowingly interacting with malicious content while believing they are communicating securely with legitimate websites. This represents a significant threat to user privacy and data security in environments where proxy servers are commonly used for network access control.
From a security standards perspective, this vulnerability maps directly to CWE-310, which describes cryptographic issues related to improper use of cryptographic functions, and CWE-295, which addresses improper certificate validation. The flaw also demonstrates characteristics of CWE-345, which deals with insufficient validation of certificate trust chains, and aligns with ATT&CK technique T1041 for data compression and T1566 for credential access through social engineering. Organizations affected by this vulnerability should immediately update to Opera 9.25 or later versions that properly validate SSL connections and implement robust certificate checking mechanisms. Additionally, network administrators should consider implementing additional security controls such as SSL inspection with proper certificate validation, monitoring for unusual CONNECT response patterns, and ensuring that proxy servers properly validate SSL certificates before forwarding requests to maintain the integrity of SSL connections in enterprise environments.