CVE-2004-0772 in Kerberos
Summary
by MITRE
Double free vulnerabilities in error handling code in krb524d for MIT Kerberos 5 (krb5) 1.2.8 and earlier may allow remote attackers to execute arbitrary code.
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Analysis
by VulDB Data Team • 08/25/2025
The vulnerability identified as CVE-2004-0772 represents a critical double free condition within the error handling mechanisms of krb524d, a component of MIT Kerberos 5 versions 1.2.8 and earlier. This flaw exists in the Kerberos authentication system's legacy conversion daemon that facilitates compatibility between Kerberos version 4 and version 5 protocols. The double free vulnerability occurs when the krb524d service processes certain malformed network requests, leading to memory management corruption that can be exploited by remote attackers to execute arbitrary code on the target system.
The technical implementation of this vulnerability stems from improper memory deallocation logic within the error handling code path of the krb524d daemon. When the service encounters malformed input data during protocol conversion operations, it fails to properly validate the memory allocation state before attempting to free the same memory block twice. This classic memory corruption flaw allows attackers to manipulate the heap memory layout and potentially overwrite critical function pointers or control structures. The vulnerability specifically manifests in scenarios where the daemon processes network packets containing malformed data structures that trigger the error handling routine, causing the system to free the same memory location multiple times without proper checks.
From an operational perspective, this vulnerability presents a severe threat to systems running older versions of MIT Kerberos 5, particularly those that rely on the krb524d service for backward compatibility. The remote exploitation capability means that attackers can leverage this vulnerability from outside the network perimeter without requiring authentication credentials. Successful exploitation could result in complete system compromise, allowing attackers to execute malicious code with the privileges of the krb524d daemon process. Given that this daemon typically runs with elevated privileges to handle authentication functions, the potential impact extends beyond simple code execution to full system takeover and privilege escalation.
The vulnerability maps directly to CWE-415, which specifically addresses double free conditions in memory management operations. This classification indicates that the flaw resides in the fundamental memory handling mechanisms of the application, making it particularly dangerous as it can be exploited through normal network communication channels. The attack pattern aligns with ATT&CK technique T1059.007, which covers command and scripting interpreter execution through remote access tools, as the exploited vulnerability enables arbitrary code execution on the target system. Organizations using affected Kerberos implementations face significant risk exposure, particularly in environments where legacy protocol support is maintained and where the krb524d service remains active.
Mitigation strategies for this vulnerability require immediate patching of all affected MIT Kerberos 5 installations to versions 1.3.0 or later where the double free condition has been resolved. System administrators should also implement network segmentation to limit access to krb524d services, disable the daemon if not required for legacy compatibility, and monitor network traffic for suspicious patterns that might indicate exploitation attempts. Additionally, organizations should conduct comprehensive vulnerability assessments to identify other potentially affected systems running older Kerberos versions, as similar memory management flaws may exist in other components of the Kerberos ecosystem. The remediation process must include thorough testing of patched systems to ensure that the fix does not introduce regressions in legitimate authentication functionality while maintaining the security posture against this specific memory corruption vulnerability.