CVE-2014-5351 in Kerberos
Summary
by MITRE
The kadm5_randkey_principal_3 function in lib/kadm5/srv/svr_principal.c in kadmind in MIT Kerberos 5 (aka krb5) before 1.13 sends old keys in a response to a -randkey -keepold request, which allows remote authenticated users to forge tickets by leveraging administrative access.
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Analysis
by VulDB Data Team • 02/21/2022
The vulnerability identified as CVE-2014-5351 resides within the Kerberos 5 implementation, specifically in the kadm5_randkey_principal_3 function located in lib/kadm5/srv/svr_principal.c. This flaw affects the kadmind service component of MIT Kerberos 5 versions prior to 1.13, creating a critical security weakness that undermines the integrity of the authentication system. The vulnerability manifests when processing administrative requests that involve random key generation while maintaining old keys, which is a common administrative operation for principal management within Kerberos environments.
The technical flaw stems from improper handling of key material in the response to authenticated administrative requests. When an administrator executes a -randkey -keepold command through the kadmind service, the system should generate new cryptographic keys while preserving the existing ones for backward compatibility. However, the vulnerable implementation fails to properly sanitize the response by including the old key material in the reply, effectively leaking sensitive cryptographic information. This behavior violates fundamental security principles of key management and creates a scenario where the old key information becomes accessible to unauthorized parties who have authenticated access to the administration interface.
The operational impact of this vulnerability is severe and directly enables privilege escalation attacks within Kerberos environments. Remote authenticated users who can access the kadmind service with administrative privileges can exploit this flaw to forge Kerberos tickets by leveraging the leaked old key information. This capability allows attackers to impersonate any principal for which they have administrative access, potentially leading to complete compromise of the Kerberos realm. The vulnerability essentially provides attackers with the cryptographic keys necessary to generate valid authentication tickets without knowing the actual passwords, making it particularly dangerous in environments where administrative access is limited but still exists.
This vulnerability aligns with CWE-310, which addresses cryptographic issues related to key management and the improper handling of cryptographic keys. The flaw also maps to ATT&CK technique T1552.001, which covers "Unsecured Credentials" through the compromise of cryptographic key material. Organizations using MIT Kerberos 5 versions before 1.13 are particularly at risk, as the vulnerability requires only authenticated access to the administration interface to exploit. The attack vector is particularly concerning because it allows attackers to escalate privileges within the Kerberos environment without needing additional authentication factors, potentially enabling lateral movement throughout the network infrastructure that relies on Kerberos for authentication.
Mitigation strategies for CVE-2014-5351 involve immediate patching of all affected MIT Kerberos 5 installations to version 1.13 or later, which contains the necessary fixes for proper key handling in the kadm5_randkey_principal_3 function. Organizations should also implement strict access controls for administrative interfaces, ensuring that only authorized personnel have access to kadmind services. Network segmentation and monitoring of administrative access patterns can help detect potential exploitation attempts. Additionally, regular key rotation policies should be enforced, and administrators should be trained to recognize suspicious activities in Kerberos administration interfaces. The fix implemented in version 1.13 properly sanitizes the response to -randkey -keepold requests, ensuring that old key material is not inadvertently transmitted to clients while maintaining the intended functionality of preserving old keys for legitimate compatibility purposes.