CVE-2004-2114 in Proxynow
Summary
by MITRE
Stack-based and heap-based buffer overflows in ProxyNow! 2.75 and earlier allow remote attackers to execute arbitrary code via a GET request with a long ftp:// URL.
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Analysis
by VulDB Data Team • 09/12/2025
The vulnerability identified as CVE-2004-2114 represents a critical security flaw affecting ProxyNow! versions 2.75 and earlier, specifically targeting both stack-based and heap-based buffer overflow conditions. This vulnerability manifests when the application processes GET requests containing excessively long ftp:// URLs, creating a scenario where attacker-controlled input can overwrite adjacent memory regions in the application's execution environment. The flaw stems from inadequate input validation and bounds checking within the proxy application's URL parsing mechanism, allowing malicious actors to craft specially crafted requests that trigger memory corruption.
The technical implementation of this vulnerability leverages the fundamental principles of buffer overflow exploitation, where the application fails to properly validate the length of incoming URL data before processing it through its internal parsing functions. When a maliciously constructed ftp:// URL exceeds the allocated buffer space, the excess data overflows into adjacent memory locations, potentially overwriting critical program variables, return addresses, or function pointers. This memory corruption can be exploited to redirect program execution flow, enabling attackers to inject and execute arbitrary code with the privileges of the affected proxy service. The vulnerability affects both stack and heap memory regions, indicating that the flaw exists at multiple levels of the application's memory management system.
From an operational perspective, this vulnerability presents a severe threat to network security infrastructure, as it allows remote code execution without requiring authentication or local access. Attackers can exploit this weakness from anywhere on the internet by simply sending a crafted GET request to the vulnerable proxy server, making it particularly dangerous for organizations that rely on proxy services for network traffic management and content filtering. The impact extends beyond simple code execution, as successful exploitation can lead to complete system compromise, data exfiltration, or the establishment of persistent backdoors within the network environment. This vulnerability directly maps to CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which addresses heap-based buffer overflow scenarios, both of which are classified as high-risk security weaknesses in the Common Weakness Enumeration catalog.
The exploitation of CVE-2004-2114 aligns with several tactics described in the MITRE ATT&CK framework, particularly focusing on initial access through network-based attacks and privilege escalation via code execution. The vulnerability represents a classic example of how insufficient input validation can create attack vectors that bypass traditional security controls. Organizations utilizing ProxyNow! services would be particularly vulnerable as this flaw affects core proxy functionality, potentially compromising the entire network traffic filtering and monitoring capabilities. The vulnerability's remote exploitability makes it especially attractive to automated attack tools and malicious actors seeking to compromise network infrastructure without requiring physical access or specialized local privileges.
Mitigation strategies for this vulnerability require immediate patching of the ProxyNow! application to version 2.80 or later, which contains fixes for the identified buffer overflow conditions. System administrators should also implement network-based restrictions to limit access to proxy services, particularly by blocking or filtering ftp:// URL requests that exceed reasonable length parameters. Additionally, deploying intrusion detection systems with signature-based detection capabilities can help identify exploitation attempts targeting this specific vulnerability. Organizations should consider implementing network segmentation to isolate proxy services and reduce the potential impact of successful exploitation, while also establishing monitoring procedures to detect unusual traffic patterns that might indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of input validation and proper memory management in network security applications, emphasizing the need for regular security updates and comprehensive vulnerability assessment programs.