CVE-2011-0283 in Kerberos
Summary
by MITRE
The Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) 1.9 allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via a malformed request packet that does not trigger a response packet.
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Analysis
by VulDB Data Team • 12/29/2024
The vulnerability identified as CVE-2011-0283 represents a critical denial of service flaw within the Key Distribution Center implementation of MIT Kerberos 5 version 1.9. This issue resides in the core authentication infrastructure that many enterprise systems rely upon for secure network authentication. The Key Distribution Center serves as the central authority for issuing and managing authentication tickets within the Kerberos protocol framework, making its stability essential for maintaining network security operations. When exploited, this vulnerability allows remote attackers to disrupt services without requiring authentication credentials, potentially compromising the availability of critical authentication infrastructure.
The technical flaw manifests as a NULL pointer dereference condition that occurs when the KDC processes malformed request packets. Specifically, the vulnerability arises from insufficient input validation within the Kerberos message processing pipeline where the system fails to properly handle malformed packet structures that do not generate response packets. This particular weakness stems from the absence of proper boundary checking and validation routines that should occur before attempting to dereference pointers within the packet parsing logic. The flaw is classified as a CWE-476_NULL_POINTER_Dereference, which represents a common software vulnerability pattern where a program attempts to access memory through a null pointer reference, leading to program termination or crash.
The operational impact of this vulnerability extends beyond simple service disruption, as it affects the fundamental availability of Kerberos-based authentication services across networks that depend on MIT Kerberos 5. Attackers can exploit this weakness by crafting specially formatted request packets that trigger the NULL pointer dereference, causing the KDC daemon to crash and restart. This disruption can cascade through enterprise environments where numerous services rely on Kerberos for authentication, potentially affecting email systems, file servers, database access, and other network resources that depend on secure authentication mechanisms. The vulnerability is particularly concerning because it operates without requiring authentication credentials, making it accessible to any remote attacker with network access to the KDC service.
Organizations affected by CVE-2011-0283 should implement immediate mitigations including patching to newer versions of MIT Kerberos 5 that contain the necessary input validation fixes. The vulnerability aligns with ATT&CK technique T1499.004 for network denial of service attacks, where adversaries leverage system weaknesses to disrupt availability of services. Network segmentation and access controls should be implemented to limit exposure of KDC services to untrusted networks, while monitoring systems should be configured to detect unusual patterns of KDC daemon restarts or crash events. Additionally, organizations should consider implementing redundant KDC services and proper failover mechanisms to maintain authentication availability during exploitation attempts. The fix typically involves enhancing input validation routines and implementing proper error handling for malformed packet processing, ensuring that all received requests are properly validated before any pointer dereference operations occur.