CVE-2014-8566 in Mod Auth Mellon
Summary
by MITRE
The mod_auth_mellon module before 0.8.1 allows remote attackers to obtain sensitive information or cause a denial of service (segmentation fault) via unspecified vectors related to a "session overflow" involving "sessions overlapping in memory."
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Analysis
by VulDB Data Team • 04/04/2022
The mod_auth_mellon module represents a critical authentication component for apache web servers that facilitates saml single sign-on functionality. This vulnerability affects versions prior to 0.8.1 and specifically targets the module's handling of session management within memory structures. The flaw manifests through a session overflow condition that occurs when multiple sessions overlap in memory space, creating a scenario where the module fails to properly manage allocated memory regions. This memory management issue directly impacts the module's ability to maintain secure session state information for authenticated users. The vulnerability presents a dual threat to system integrity as it can either expose sensitive authentication data or trigger a segmentation fault leading to service disruption. The root cause lies in improper bounds checking and memory allocation handling within the session management subsystem of the module.
The technical exploitation of this vulnerability involves manipulating session creation and management operations to force memory overlaps that result in either information disclosure or system crashes. When sessions overlap in memory, the module's internal data structures become corrupted, potentially exposing session tokens, user credentials, or other sensitive authentication information stored in the overlapping memory regions. The segmentation fault occurs when the module attempts to access or modify memory locations that have been corrupted due to the overlapping session data. This type of vulnerability falls under the category of memory corruption issues that are commonly classified as CWE-121 heap-based buffer overflow or CWE-125 out-of-bounds read/write conditions. The vulnerability demonstrates poor memory management practices and inadequate input validation within the authentication module's session handling logic.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to include potential credential exposure and unauthorized access to protected resources. Remote attackers can leverage this weakness to either extract session information that could be used to impersonate legitimate users or to crash the web server through segmentation faults, thereby disrupting service availability. The memory overlap condition can occur during high-concurrency scenarios when multiple authentication requests are processed simultaneously, making the vulnerability particularly dangerous in production environments. The exposure of sensitive information through this vulnerability could compromise user authentication tokens, session identifiers, and potentially other authentication-related data stored in memory. This creates a significant risk for organizations relying on saml authentication through mod_auth_mellon, as successful exploitation could lead to complete authentication bypass or unauthorized access to protected applications and resources.
Mitigation strategies for this vulnerability require immediate patching to version 0.8.1 or later, which includes proper memory management fixes and enhanced bounds checking for session data structures. Organizations should also implement monitoring for unusual authentication request patterns that might indicate exploitation attempts, particularly around session creation and renewal operations. The fix addresses the underlying memory management issues by implementing proper allocation boundaries and ensuring that session data does not overlap in memory regions. Additionally, system administrators should consider implementing rate limiting and authentication request throttling to reduce the likelihood of successful exploitation through high-concurrency attacks. The vulnerability demonstrates the importance of proper memory management in authentication modules and aligns with attack patterns documented in the attack mitigation framework where memory corruption issues are frequently used to gain unauthorized access or cause service disruption. Organizations should also review their authentication infrastructure for similar memory management issues in other modules and ensure comprehensive testing of session handling logic under stress conditions to prevent similar vulnerabilities from being introduced in future implementations.