CVE-2008-5676 in ModSecurity
Summary
by MITRE
Multiple unspecified vulnerabilities in the ModSecurity (aka mod_security) module 2.5.0 through 2.5.5 for the Apache HTTP Server, when SecCacheTransformations is enabled, allow remote attackers to cause a denial of service (daemon crash) or bypass the product s functionality via unknown vectors related to "transformation caching."
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Analysis
by VulDB Data Team • 10/22/2018
The vulnerability identified as CVE-2008-5676 affects the ModSecurity module version 2.5.0 through 2.5.5 when operating with the SecCacheTransformations directive enabled. This represents a critical security flaw within the web application firewall component that serves as a protective layer for Apache HTTP Server deployments. The vulnerability stems from improper handling of transformation caching mechanisms that are designed to optimize performance by caching processed data transformations. When SecCacheTransformations is enabled, the module attempts to cache transformation results to reduce processing overhead, but this caching functionality contains implementation flaws that can be exploited by remote attackers to compromise system stability and security controls.
The technical flaw manifests through unspecified attack vectors that specifically target the transformation caching subsystem within ModSecurity. When the SecCacheTransformations feature is active, the module maintains cached versions of transformed data to improve performance during subsequent requests. However, the caching mechanism contains memory management issues and improper validation of cached data that can be manipulated by malicious actors. These flaws allow attackers to craft specific requests that trigger buffer overflows, memory corruption, or other invalid memory access conditions within the ModSecurity daemon process. The vulnerability operates at the application layer and can be exploited through HTTP requests without requiring authentication or privileged access, making it particularly dangerous in production environments where ModSecurity serves as a primary security control.
The operational impact of this vulnerability extends beyond simple denial of service conditions to encompass potential bypass of security controls within the ModSecurity framework. Remote attackers can cause daemon crashes that result in complete service disruption, forcing administrators to restart the Apache server and potentially leading to extended downtime for affected web applications. Additionally, the vulnerability may enable attackers to bypass security rules and filtering mechanisms that ModSecurity normally enforces, allowing malicious payloads to pass through the security layer undetected. This dual nature of the vulnerability makes it particularly concerning for organizations that rely on ModSecurity for protecting their web applications from common threats such as sql injection attacks, cross site scripting attempts, and other web application exploits.
Organizations affected by this vulnerability should immediately disable the SecCacheTransformations directive if transformation caching is not absolutely necessary for their specific use cases. The most effective immediate mitigation involves modifying the ModSecurity configuration to disable the problematic caching feature through the directive SecCacheTransformations off. Security administrators should also consider upgrading to ModSecurity version 2.5.6 or later, which contains patches addressing the transformation caching vulnerabilities. Network administrators should implement monitoring and alerting for unusual daemon crash patterns or unexpected service disruptions that may indicate exploitation attempts. The vulnerability aligns with CWE-121 and CWE-122 categories related to buffer overflow conditions and memory management issues, while also mapping to ATT&CK techniques involving service disruption and evasion of security controls. Organizations should conduct thorough security assessments to identify all systems running vulnerable ModSecurity versions and ensure comprehensive patch management processes are in place to prevent similar vulnerabilities from affecting their security infrastructure.