CVE-2007-1224 in NetProxy
Summary
by MITRE
Grok Developments NetProxy 4.03 allows remote attackers to bypass URL filtering via a request that omits "http://" from the URL and specifies the destination port (:80).
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Analysis
by VulDB Data Team • 08/25/2024
The vulnerability identified as CVE-2007-1224 affects Grok Developments NetProxy version 4.03, a web proxy server software designed to filter and control internet access. This security flaw represents a significant bypass mechanism that undermines the intended URL filtering capabilities of the proxy system. The vulnerability stems from insufficient input validation and parsing logic within the proxy's URL handling routines, allowing malicious actors to circumvent content filtering policies through carefully crafted requests. The specific nature of this flaw demonstrates a critical weakness in the proxy's protocol interpretation and validation mechanisms, potentially exposing organizations to unauthorized access to restricted web resources.
The technical implementation of this vulnerability exploits a parsing inconsistency in how NetProxy processes incoming HTTP requests. When a client submits a request that omits the standard "http://" protocol prefix and instead specifies the destination port explicitly using the ":80" syntax, the proxy fails to properly validate or normalize the URL structure. This parsing failure occurs because the proxy's URL parser does not adequately handle malformed or non-standard URL formats that lack the conventional protocol specification. The vulnerability specifically targets the proxy's inability to recognize and normalize such requests, allowing them to bypass the filtering rules that would normally be applied to standard HTTP URLs. This represents a classic example of input validation failure where the system does not properly sanitize or normalize user input before processing.
From an operational perspective, this vulnerability creates a substantial risk for organizations relying on NetProxy for content filtering and security policy enforcement. Attackers can exploit this flaw to access blocked websites, bypass corporate security policies, and potentially gain access to malicious content that would normally be filtered. The impact extends beyond simple content bypass, as it undermines the entire security posture of networks using this proxy solution. Organizations may experience unauthorized access to sensitive or inappropriate websites, potential data exfiltration opportunities, and overall weakening of their network security controls. The vulnerability's remote nature means that attackers do not need physical access to the network or the proxy server itself, making it particularly dangerous in enterprise environments where such proxies are commonly deployed.
The technical flaw aligns with CWE-20, which addresses "Improper Input Validation," and demonstrates how inadequate parsing and validation can lead to security bypasses. This vulnerability also relates to ATT&CK technique T1071.004, which covers "Application Layer Protocol: DNS" but in this case represents a protocol bypass rather than DNS manipulation. The flaw essentially creates a pathway for attackers to manipulate the proxy's protocol handling logic, potentially enabling further exploitation techniques. Organizations should consider this vulnerability as part of a broader attack surface that includes other protocol parsing issues and input validation weaknesses. The vulnerability's existence highlights the importance of proper input normalization and protocol handling in security-critical applications, particularly in proxy and filtering systems where malformed inputs can lead to complete bypass of security controls.
Mitigation strategies should include immediate patching of the NetProxy software to the latest available version that addresses this specific vulnerability. Organizations should also implement additional monitoring and logging of proxy requests to detect anomalous URL patterns that might indicate exploitation attempts. Network segmentation and additional filtering layers can provide defense-in-depth protection against exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper input validation and protocol handling in security software, as even seemingly minor parsing inconsistencies can lead to significant security implications. Regular security assessments of proxy and filtering systems should include testing for similar input validation weaknesses to prevent exploitation of similar vulnerabilities.