CVE-2007-5972 in Kerberos
Summary
by MITRE
Double free vulnerability in the krb5_def_store_mkey function in lib/kdb/kdb_default.c in MIT Kerberos 5 (krb5) 1.5 has unknown impact and remote authenticated attack vectors. NOTE: the free operations occur in code that stores the krb5kdc master key, and so the attacker must have privileges to store this key.
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Analysis
by VulDB Data Team • 07/29/2021
The CVE-2007-5972 vulnerability represents a critical double free error within the MIT Kerberos 5 authentication system, specifically within the krb5_def_store_mkey function located in lib/kdb/kdb_default.c. This flaw exists in Kerberos 5 version 1.5 and demonstrates a classic memory management vulnerability that can lead to arbitrary code execution or system instability. The vulnerability is particularly concerning because it operates within the master key storage mechanism of the Kerberos domain controller, making it a high-value target for attackers who can authenticate to the system. The double free condition occurs when the same memory block is freed twice, which can result in memory corruption and potentially allow attackers to manipulate the program's execution flow. According to CWE-415, this vulnerability falls under the category of double free conditions, which are well-documented memory safety issues that can be exploited to execute malicious code or cause denial of service conditions.
The operational impact of this vulnerability extends beyond simple system crashes, as it provides a pathway for authenticated attackers to gain elevated privileges within the Kerberos infrastructure. Since the attack vector requires authentication to store the master key, it limits the exploitability to users who already possess valid credentials, but this still represents a significant security risk in environments where privilege escalation is a concern. The vulnerability's remote nature means that attackers can potentially exploit it from network locations, though they must first establish authentication to the Kerberos service. This characteristic aligns with ATT&CK technique T1078 which covers legitimate credentials and valid accounts as a means of gaining access to systems. The master key storage functionality is critical to Kerberos security because it serves as the foundation for all cryptographic operations within the domain, making this vulnerability particularly dangerous.
Mitigation strategies for CVE-2007-5972 should focus on immediate patching of affected systems, as the vulnerability has been addressed in subsequent versions of MIT Kerberos 5. Organizations should implement strict access controls to prevent unauthorized users from accessing master key storage functions, as this would significantly reduce the attack surface. The principle of least privilege should be enforced when granting permissions to store master keys, limiting access to only those users who absolutely require these capabilities. Additionally, regular security audits should verify that no unauthorized modifications have been made to the Kerberos configuration or code, as this vulnerability could potentially be exploited to maintain persistence within the authentication infrastructure. Network segmentation and monitoring of Kerberos traffic can help detect anomalous behavior that might indicate exploitation attempts. The vulnerability also highlights the importance of thorough code review processes, particularly for memory management functions that handle critical security data, as similar issues could exist in other parts of the Kerberos codebase or related security systems.