CVE-2003-0993 in Management Center
Summary
by MITRE
mod_access in Apache 1.3 before 1.3.30, when running big-endian 64-bit platforms, does not properly parse Allow/Deny rules using IP addresses without a netmask, which could allow remote attackers to bypass intended access restrictions.
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Analysis
by VulDB Data Team • 07/03/2019
The vulnerability described in CVE-2003-0993 represents a critical access control flaw in the Apache HTTP Server version 1.3.x series, specifically affecting systems operating on big-endian 64-bit architectures. This issue stems from improper handling of IP address parsing within the mod_access module, which is responsible for implementing access control mechanisms based on client IP addresses. The flaw manifests when administrators configure access restrictions using Allow and Deny directives without specifying netmask values, creating a scenario where the server fails to correctly interpret the intended access policies. The vulnerability is particularly significant because it affects the fundamental security model of web server access control, potentially allowing unauthorized users to bypass access restrictions that should have been enforced by the server configuration.
The technical root cause of this vulnerability lies in the way the mod_access module processes IP addresses on big-endian 64-bit systems. When IP addresses are specified without netmask information, the parsing algorithm fails to correctly handle the byte ordering and address representation on these specific architectures. This parsing error results in incorrect evaluation of access control rules, where the server may incorrectly interpret the intended scope of the Allow or Deny directives. The flaw specifically impacts the comparison logic used to match client IP addresses against configured access rules, causing legitimate access restrictions to be bypassed. This type of vulnerability falls under CWE-284, which addresses improper access control mechanisms, and represents a classic case of insufficient input validation where the server fails to properly validate the format and interpretation of IP address specifications.
The operational impact of this vulnerability is severe and directly affects the security posture of Apache servers running on affected platforms. Remote attackers can exploit this weakness to gain unauthorized access to web resources that should have been restricted based on IP address. The vulnerability creates a backdoor that allows malicious users to bypass authentication and authorization mechanisms, potentially leading to data theft, service disruption, or further exploitation of the compromised server. The attack vector is particularly dangerous because it requires no special privileges or credentials beyond basic network access to the web server. This vulnerability directly violates the principle of least privilege and can result in complete compromise of web server resources, making it a high-priority issue for system administrators to address immediately.
Mitigation strategies for this vulnerability include upgrading to Apache 1.3.30 or later versions where the parsing issue has been resolved, as well as implementing additional security measures to compensate for the vulnerability in older systems. System administrators should also ensure that all IP address specifications in access control directives include explicit netmask values to avoid triggering the parsing error. The recommended approach involves comprehensive testing of access control configurations on affected systems, followed by immediate patch deployment. Organizations should also consider implementing network-level access controls, intrusion detection systems, and monitoring solutions to detect potential exploitation attempts. This vulnerability highlights the importance of thorough testing on all supported platforms and architectures, particularly when dealing with low-level network protocols and security-critical modules like access control filters. The issue also demonstrates the need for adherence to security best practices such as specifying complete IP address ranges and regularly updating security software to protect against known vulnerabilities.