CVE-2011-4151 in Kerberos
Summary
by MITRE
The krb5_db2_lockout_audit function in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) 1.8 through 1.8.4, when the db2 (aka Berkeley DB) back end is used, allows remote attackers to cause a denial of service (assertion failure and daemon exit) via unspecified vectors, a different vulnerability than CVE-2011-1528.
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Analysis
by VulDB Data Team • 12/02/2024
The vulnerability identified as CVE-2011-4151 represents a critical denial of service flaw within the MIT Kerberos 5 implementation that specifically affects versions 1.8 through 1.8.4 when utilizing the Berkeley DB backend storage mechanism. This issue manifests within the krb5_db2_lockout_audit function of the Key Distribution Center component, which serves as the central authority for authentication services in Kerberos environments. The vulnerability arises from improper handling of certain database operations that trigger assertion failures, ultimately causing the KDC daemon to terminate unexpectedly and disrupting authentication services for all users relying on the Kerberos infrastructure.
The technical exploitation of this vulnerability occurs through unspecified vectors that manipulate the database locking mechanisms within the Berkeley DB backend, leading to a condition where the assertion failure occurs during normal operational procedures. This flaw demonstrates characteristics consistent with CWE-129, which addresses improper handling of buffer indices and array bounds, and potentially CWE-611, concerning improper access control in database operations. The assertion failure represents a fundamental breakdown in the software's error handling mechanism, where the system fails to properly validate database states or handle concurrent access scenarios that could occur during normal authentication workflows.
Operationally, this vulnerability presents a significant risk to organizations relying on Kerberos authentication services, as it can be exploited remotely without requiring authentication credentials or privileged access. The resulting denial of service impacts the availability of authentication services across the entire Kerberos realm, potentially affecting thousands of users and systems that depend on centralized authentication. Attackers can leverage this vulnerability to disrupt business operations by causing the KDC daemon to crash repeatedly, leading to cascading failures in dependent services and applications that rely on Kerberos for secure authentication. The impact extends beyond simple service disruption as it can compromise the integrity of the authentication infrastructure and potentially create opportunities for further exploitation attempts.
Organizations should immediately implement mitigations including upgrading to patched versions of MIT Kerberos 5, specifically versions beyond 1.8.4, and applying the relevant security patches that address the database locking mechanism issues. System administrators should also consider implementing monitoring solutions that can detect KDC daemon restarts and alert on unusual patterns of service disruptions. Additionally, implementing proper access controls and network segmentation can limit the attack surface, while maintaining redundant KDC services can provide resilience against single points of failure. The vulnerability highlights the importance of proper error handling in database-backed services and aligns with ATT&CK technique T1499.004, which covers network disruption through denial of service attacks, emphasizing the need for robust defensive measures in authentication infrastructure components.