CVE-2004-0434 in Heimdal
Summary
by MITRE
k5admind (kadmind) for Heimdal allows remote attackers to execute arbitrary code via a Kerberos 4 compatibility administration request whose framing length is less than 2, which leads to a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 09/02/2019
The vulnerability identified as CVE-2004-0434 affects the k5admind component of the Heimdal Kerberos implementation, specifically targeting the Kerberos 4 compatibility administration request processing functionality. This flaw exists within the handling of administrative requests that maintain backward compatibility with the older Kerberos 4 protocol. The vulnerability stems from insufficient input validation during the processing of framed administrative commands, creating a critical security gap that can be exploited by remote attackers to execute arbitrary code on affected systems. The issue manifests when the kadmind service receives a specially crafted administrative request where the framing length is less than the minimum required value of 2 bytes, triggering a heap-based buffer overflow condition.
The technical exploitation of this vulnerability occurs through a heap-based buffer overflow attack that leverages malformed administrative request framing. When kadmind processes an administrative request with a framing length below the expected minimum of 2 bytes, the application fails to properly validate the input before attempting to copy data into a heap-allocated buffer. This insufficient boundary checking allows an attacker to overwrite adjacent memory regions, potentially leading to arbitrary code execution with the privileges of the kadmind process. The vulnerability falls under the Common Weakness Enumeration category of CWE-121, which encompasses heap-based buffer overflow conditions, and represents a classic example of improper input validation leading to memory corruption. The attack vector is particularly concerning as it requires no authentication and can be executed remotely, making it accessible to any attacker who can reach the kadmind service port.
The operational impact of this vulnerability extends beyond simple code execution, as it can compromise the entire Kerberos infrastructure and potentially provide attackers with elevated privileges within the authenticated network environment. Since kadmind typically operates with administrative privileges to manage Kerberos principals and keys, successful exploitation could enable attackers to create malicious principals, modify existing accounts, or even gain complete control over the Kerberos realm. The vulnerability affects systems running Heimdal implementations of Kerberos 4 compatibility mode, which were commonly found in legacy environments that had not fully migrated to Kerberos 5. Organizations relying on this older compatibility layer for backward support were particularly at risk, as the flaw could be exploited to undermine the core authentication services that protect network resources and sensitive data. The attack could potentially lead to credential theft, privilege escalation, and unauthorized access to protected network resources, making it a critical concern for enterprise security.
Mitigation strategies for CVE-2004-0434 should focus on immediate patching of the Heimdal implementation to address the buffer overflow condition in kadmind's administrative request handling. Organizations should prioritize updating their Kerberos implementations to versions that properly validate framing lengths and implement robust input sanitization for all administrative requests. Additionally, network segmentation and access controls should be implemented to limit exposure of kadmind services to untrusted networks, while monitoring systems should be configured to detect anomalous administrative request patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of maintaining up-to-date cryptographic implementations and highlights the risks associated with maintaining legacy protocol compatibility layers that may contain unpatched security flaws. Security teams should also consider implementing intrusion detection systems that can identify suspicious administrative request patterns and establish baseline network behavior to detect potential exploitation attempts. The remediation process should include comprehensive testing of patched implementations to ensure that the fix does not introduce regressions in legitimate administrative functionality while maintaining the security posture of the Kerberos infrastructure.