CVE-2008-0062 in Kerberos 5
Summary
by MITRE
KDC in MIT Kerberos 5 (krb5kdc) does not set a global variable for some krb4 message types, which allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via crafted messages that trigger a NULL pointer dereference or double-free.
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Analysis
by VulDB Data Team • 01/12/2025
The vulnerability identified as CVE-2008-0062 represents a critical flaw in the Key Distribution Center implementation of MIT Kerberos 5, specifically within the krb5kdc service that handles authentication requests. This issue affects the Kerberos authentication system widely used in enterprise environments and operating systems including various versions of unix-like systems and Microsoft Windows domains. The vulnerability stems from improper handling of certain Kerberos version 4 message types within the Kerberos version 5 key distribution center, creating a dangerous condition where global variables remain unset during specific authentication message processing scenarios.
The technical root cause of this vulnerability lies in the insufficient validation and initialization of global variables within the krb5kdc daemon when processing krb4 message types. When the service receives specially crafted authentication messages that correspond to specific krb4 message types, the code path fails to properly initialize critical global variables before attempting to access or manipulate them. This failure creates a scenario where subsequent operations attempt to dereference NULL pointers or trigger double-free operations, both of which can lead to system instability. The vulnerability specifically affects message types that are processed through the Kerberos 5 compatibility layer, where krb4 message formats are translated for processing within the krb5kdc environment.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable remote code execution, making it particularly dangerous for networked environments. Attackers can exploit this weakness by sending carefully constructed authentication messages to the krb5kdc service, which causes the daemon to crash and potentially allows for arbitrary code execution on the affected system. The NULL pointer dereference conditions can cause the service to terminate abruptly, leading to denial of service for legitimate authentication requests and potentially providing attackers with a foothold for further exploitation. The double-free condition presents additional risks as memory corruption can occur, potentially enabling attackers to manipulate memory layout and execute malicious code with the privileges of the krb5kdc process.
This vulnerability aligns with CWE-476, which describes NULL pointer dereference conditions, and CWE-415, which covers double-free conditions in memory management. From an ATT&CK framework perspective, this vulnerability maps to T1190 for exploitation of remote services and T1068 for local privilege escalation potential. The attack surface is particularly concerning given that krb5kdc typically runs with elevated privileges and serves as a critical component in authentication infrastructure. Organizations using MIT Kerberos implementations should prioritize patching this vulnerability as it represents a significant risk to authentication system integrity and overall network security posture. The vulnerability demonstrates the importance of proper input validation and memory management in critical authentication services, particularly those handling cross-version compatibility scenarios.
Mitigation strategies should include immediate patching of affected MIT Kerberos versions, implementing network segmentation to limit access to krb5kdc services, and monitoring for suspicious authentication traffic patterns. Organizations should also consider implementing additional authentication layers and regular security assessments of their Kerberos implementations to identify similar vulnerabilities in other components of their authentication infrastructure.