CVE-2005-0182 in HTTP Server
Summary
by MITRE
The mod_dosevasive module 1.9 and earlier for Apache creates temporary files with predictable filenames, which could allow remote attackers to overwrite arbitrary files via a symlink attack.
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Analysis
by VulDB Data Team • 03/10/2021
The mod_dosevasive module represents a critical security vulnerability within Apache web server configurations that has persisted since the early 2000s. This module was designed to provide protection against distributed denial-of-service attacks by monitoring and limiting access patterns from individual clients. However, the implementation contained a fundamental flaw that created a dangerous condition in the temporary file handling mechanism. The vulnerability specifically affects versions 1.9 and earlier, indicating that despite being identified over a decade ago, it continues to pose risks in legacy systems where proper patching has not occurred. The issue stems from the module's approach to creating temporary files during its operation, which uses predictable naming conventions that expose the system to targeted attacks.
The technical flaw within mod_dosevasive arises from its use of predictable filename patterns when creating temporary files for tracking client access patterns and implementing rate limiting measures. When the module operates, it generates temporary files in system directories to store information about client connections, request rates, and other monitoring data. These temporary files are created with filenames that follow a deterministic pattern based on factors such as client IP addresses, timestamps, or other easily guessable parameters. This predictability creates an opportunity for attackers to exploit the system through symbolic link manipulation attacks, where malicious actors create symbolic links with the same predictable names before the legitimate temporary files are created. This timing vulnerability allows attackers to position their symbolic links in such a way that when the module attempts to create its temporary files, it actually writes data to locations controlled by the attacker rather than the intended temporary directory.
The operational impact of this vulnerability extends beyond simple file overwrites and represents a serious privilege escalation risk within Apache server environments. When an attacker successfully executes a symlink attack against the mod_dosevasive module, they gain the ability to write arbitrary data to locations within the file system where they might not otherwise have write permissions. This capability can be leveraged to overwrite critical system files, configuration files, or even executable components that could lead to complete system compromise. The vulnerability is particularly dangerous because it operates at the web server level where the module runs with elevated privileges, potentially allowing attackers to manipulate the server's operation or inject malicious code into the web application environment. The attack vector requires only a remote connection to the web server and knowledge of the predictable filename patterns, making it accessible to attackers with minimal technical expertise.
Mitigation strategies for this vulnerability must address both immediate operational concerns and long-term security posture improvements. The most effective immediate solution involves upgrading to mod_dosevasive version 1.10 or later, where the developers addressed the predictable filename issue through improved randomization and secure temporary file creation mechanisms. Organizations should also implement proper file system permissions and directory isolation to limit the impact of potential exploitation attempts, ensuring that the temporary directories used by the module have restricted write permissions and are not accessible to untrusted users. System administrators should conduct comprehensive audits of all Apache installations to identify and remediate vulnerable configurations, particularly in legacy environments where patch management processes may be inadequate. Additionally, implementing proper monitoring and logging of temporary file creation activities can help detect potential exploitation attempts and provide early warning of active attacks. This vulnerability aligns with CWE-377 and CWE-378 categories related to insecure temporary file creation and poor file handling practices. The attack scenario demonstrates characteristics consistent with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation could enable attackers to execute arbitrary code on the affected system through manipulated temporary files. Organizations should also consider implementing additional security controls such as SELinux policies or AppArmor profiles to further restrict the module's file system access and reduce the attack surface.