CVE-2014-8567 in Mod Auth Mellon
Summary
by MITRE
The mod_auth_mellon module before 0.8.1 allows remote attackers to cause a denial of service (Apache HTTP server crash) via a crafted logout request that triggers a read of uninitialized data.
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Analysis
by VulDB Data Team • 04/04/2022
The mod_auth_mellon module represents a critical vulnerability in the Apache HTTP server ecosystem that emerged through improper memory management during authentication logout processes. This vulnerability specifically affects versions prior to 0.8.1 and enables remote attackers to execute a denial of service attack by crafting malicious logout requests. The flaw manifests when the module attempts to process a logout request that contains malformed or unexpected data structures, leading to a scenario where uninitialized memory segments are accessed during the processing pipeline. The module's failure to properly validate input parameters during logout operations creates an exploitable condition that can be leveraged to crash the Apache HTTP server instance. This vulnerability directly impacts the availability of web services that rely on SAML-based authentication mechanisms, as the module serves as a bridge between Apache and SAML identity providers. The issue stems from inadequate defensive programming practices where the code does not properly initialize memory segments before accessing them, creating a classic uninitialized memory access condition that can be triggered through network-based attacks. The vulnerability demonstrates a clear weakness in the module's input validation and memory management protocols, particularly during the authentication flow termination phase.
The technical exploitation of this vulnerability occurs when an attacker crafts a specially formatted logout request that contains data structures designed to trigger the uninitialized memory read condition. The mod_auth_mellon module, which implements SAML authentication for Apache servers, fails to properly sanitize or validate the logout parameters before processing them. When the module encounters such malformed input during the logout sequence, it attempts to read memory locations that have not been properly initialized, leading to unpredictable behavior and ultimately causing the Apache server process to crash. This type of vulnerability falls under the category of memory safety issues and aligns with common CWE classifications related to improper initialization of data structures. The attack vector is entirely remote, requiring no authentication or local access, making it particularly dangerous as it can be exploited from any network location. The crash occurs during the server's response handling phase when the module attempts to process the logout request and access uninitialized memory segments, resulting in an immediate termination of the Apache process. The vulnerability's impact extends beyond simple service disruption as it can be used to repeatedly crash the web server, effectively rendering the service unavailable to legitimate users. The exploitation mechanism relies on the module's failure to implement proper bounds checking and memory initialization protocols, creating a condition where the server's execution flow encounters undefined behavior upon accessing uninitialized data structures.
The operational impact of CVE-2014-8567 extends significantly beyond immediate service disruption, as organizations relying on SAML-based authentication systems face potential business continuity issues and increased operational overhead. When an Apache server running vulnerable versions of mod_auth_mellon experiences crashes due to this vulnerability, it can result in complete service outages for web applications that depend on SAML authentication. The vulnerability particularly affects organizations using federated identity management systems where Apache serves as the web server front-end for applications requiring SAML authentication. Security teams must implement immediate mitigations to prevent exploitation, as the vulnerability can be leveraged by automated scanning tools to identify and exploit vulnerable systems. The denial of service condition can be sustained through repeated attacks, potentially causing prolonged service unavailability that impacts user access and business operations. Organizations may also face increased monitoring requirements and incident response activities as they attempt to detect and remediate exploitation attempts. The vulnerability's impact is compounded when considering that many organizations may not regularly test their authentication modules for such flaws, leading to extended periods of exposure. The issue also represents a potential attack surface for more sophisticated exploits that could leverage the server crash condition to execute additional malicious activities or escalate privileges.
Mitigation strategies for CVE-2014-8567 primarily focus on immediate version upgrades to mod_auth_mellon 0.8.1 or later, which contain the necessary patches to address the uninitialized memory read condition. System administrators should prioritize patching affected Apache installations to ensure that the module's memory management routines properly initialize all data structures before access. Organizations should implement network-based monitoring solutions to detect unusual logout request patterns that may indicate exploitation attempts. The vulnerability's remediation requires careful attention to ensure that Apache configurations remain functional after patching, as the updated module may introduce compatibility considerations with existing SAML configurations. Security teams should conduct thorough testing of patched environments to verify that legitimate authentication flows continue to operate correctly while preventing the denial of service condition. Additionally, implementing access controls and rate limiting on logout endpoints can provide additional defense-in-depth measures that reduce the effectiveness of automated exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper memory management in authentication modules and highlights the necessity of regular security assessments of identity management components. Organizations should also consider implementing automated vulnerability scanning tools that can identify outdated versions of authentication modules and alert administrators to potential exposure risks. The incident underscores the importance of maintaining current security patches for all web server components, particularly those handling authentication and authorization functions, as these modules represent high-value targets for attackers seeking to disrupt service availability.