CVE-2002-0392 in HTTP Server
Summary
by MITRE
Apache 1.3 through 1.3.24, and Apache 2.0 through 2.0.36, allows remote attackers to cause a denial of service and possibly execute arbitrary code via a chunk-encoded HTTP request that causes Apache to use an incorrect size.
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Analysis
by VulDB Data Team • 12/23/2024
This vulnerability affects Apache HTTP Server versions 1.3 through 1.3.24 and 2.0 through 2.0.36, representing a critical flaw in the HTTP request processing mechanism that can lead to both denial of service conditions and potential remote code execution. The vulnerability specifically targets the chunked transfer encoding implementation within Apache's HTTP handling logic, where an attacker can craft malicious HTTP requests that exploit improper size calculations during request processing. This flaw falls under the CWE-129 vulnerability category, which encompasses improper validation of array indices and buffer overflows that can result in arbitrary code execution. The issue stems from Apache's failure to properly validate the size parameter in chunk-encoded HTTP requests, allowing attackers to manipulate the expected chunk size value which then affects how the server allocates memory and processes incoming data streams.
The technical exploitation occurs when Apache encounters a malformed chunked HTTP request where the chunk size is incorrectly specified, leading to memory allocation errors and potential buffer overflows in the server's request parsing components. This vulnerability is particularly dangerous because it can be triggered through standard HTTP traffic without requiring authentication or special privileges, making it an ideal candidate for automated attacks. The improper handling of chunked encoding follows ATT&CK technique T1210, which involves exploiting weaknesses in network protocols to gain unauthorized access or disrupt services. When an attacker sends a specially crafted request with an invalid chunk size, the Apache server's internal buffer management routines become corrupted, potentially leading to stack corruption or heap corruption that could be leveraged for remote code execution depending on the system configuration and memory layout.
The operational impact of this vulnerability extends beyond simple denial of service, as successful exploitation can allow attackers to execute arbitrary code on the affected Apache server with the privileges of the web server process. This creates a significant risk for organizations that rely on Apache as their primary web server, as compromised servers can become part of botnets, used for further attacks, or exploited to gain access to internal networks. The vulnerability affects both Apache 1.3 and 2.0 series releases, indicating it was present across multiple major versions and likely impacted a substantial portion of the internet infrastructure at the time of discovery. Organizations running affected versions face potential data breaches, service disruption, and compliance violations, particularly in regulated environments where maintaining service availability and data integrity are paramount.
Mitigation strategies for this vulnerability include immediate patching of affected Apache installations to versions that properly validate chunked encoding parameters, implementing network-level restrictions to filter out malformed HTTP requests, and deploying intrusion detection systems that can identify suspicious chunked encoding patterns. Organizations should also consider implementing web application firewalls that can detect and block malformed HTTP requests before they reach the Apache server. The patching process requires careful testing to ensure compatibility with existing web applications, as improper configuration changes could introduce new issues. Additionally, system administrators should monitor their Apache server logs for unusual patterns in HTTP request handling that might indicate exploitation attempts, and consider implementing rate limiting or connection throttling to reduce the effectiveness of denial of service attacks. This vulnerability serves as a reminder of the critical importance of keeping web server software up to date and maintaining robust security monitoring practices to detect and respond to emerging threats in the HTTP protocol stack.