CVE-2004-0523 in Kerberos
Summary
by MITRE
Multiple buffer overflows in krb5_aname_to_localname for MIT Kerberos 5 (krb5) 1.3.3 and earlier allow remote attackers to execute arbitrary code as root.
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Analysis
by VulDB Data Team • 07/12/2025
The vulnerability identified as CVE-2004-0523 represents a critical buffer overflow flaw within the MIT Kerberos 5 implementation that affects versions 1.3.3 and earlier. This vulnerability specifically targets the krb5_aname_to_localname function which serves as a crucial component in the Kerberos authentication process. The flaw arises from insufficient input validation when processing authentication names, creating opportunities for malicious actors to exploit memory corruption issues that can lead to privilege escalation.
The technical nature of this vulnerability stems from improper bounds checking within the krb5_aname_to_localname function where attacker-controlled input is processed without adequate sanitization. When the function encounters authentication names exceeding predetermined buffer limits, it fails to properly handle the overflow condition, allowing attackers to overwrite adjacent memory locations. This memory corruption can be strategically manipulated to inject and execute malicious code with the privileges of the root user, effectively compromising the entire Kerberos infrastructure.
The operational impact of this vulnerability extends far beyond simple code execution as it represents a complete compromise of the authentication system's integrity. Organizations relying on MIT Kerberos 5 for secure authentication across network services, file systems, and application access control face severe risks when exposed to this vulnerability. Attackers exploiting this flaw can gain unauthorized root access to systems, potentially leading to complete network infiltration, data exfiltration, and persistent backdoor establishment. The remote nature of the exploit means that attackers need not have physical access to target systems, making the vulnerability particularly dangerous for distributed environments.
Security practitioners should immediately implement mitigations including upgrading to MIT Kerberos 5 versions 1.4 or later where this vulnerability has been addressed through proper input validation and buffer management. System administrators must also deploy network segmentation and access controls to limit exposure while monitoring for suspicious authentication patterns that may indicate exploitation attempts. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and maps to ATT&CK technique T1078.001 for valid accounts and T1068 for exploit for privilege escalation. Organizations should also consider implementing intrusion detection systems capable of identifying malformed Kerberos authentication requests and establish incident response procedures specifically addressing authentication system compromises. Regular security audits of Kerberos configurations and privilege management should be conducted to ensure comprehensive protection against similar vulnerabilities in the authentication infrastructure.