CVE-2003-0139 in Kerberos
Summary
by MITRE
Certain weaknesses in the implementation of version 4 of the Kerberos protocol (krb4) in the krb5 distribution, when triple-DES keys are used to key krb4 services, allow an attacker to create krb4 tickets for unauthorized principals using a cut-and-paste attack and "ticket splicing."
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Analysis
by VulDB Data Team • 01/19/2025
The vulnerability described in CVE-2003-0139 represents a critical flaw in the Kerberos version 4 protocol implementation within the krb5 distribution that specifically affects systems utilizing triple-DES encryption for krb4 services. This weakness stems from insufficient cryptographic validation mechanisms during ticket generation and processing, creating a pathway for unauthorized access through sophisticated attack techniques that exploit the protocol's design limitations. The vulnerability exists in the cryptographic implementation rather than the protocol specification itself, making it particularly dangerous as it undermines the fundamental security assumptions of the authentication system.
The technical flaw manifests through a cut-and-paste attack vector that leverages the specific handling of triple-DES keys in krb4 service implementations. Attackers can manipulate existing krb4 tickets by extracting and reassembling cryptographic components from valid tickets to construct new tickets for unauthorized principals. This ticket splicing technique exploits the fact that certain cryptographic operations in the krb4 implementation do not properly validate the integrity of ticket components against the expected key derivation processes. The vulnerability specifically impacts systems where krb4 services are configured to use triple-DES encryption, creating a scenario where attackers can bypass authentication mechanisms without requiring knowledge of legitimate user credentials or private keys.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it can enable attackers to escalate privileges and gain persistent access to network resources that rely on Kerberos authentication. The attack requires the adversary to have access to valid krb4 tickets from legitimate users, but once obtained, the attacker can create tickets for any principal within the Kerberos realm, potentially allowing them to impersonate administrators or other high-privilege accounts. This vulnerability directly violates the principle of authentication integrity and can lead to complete compromise of the Kerberos authentication infrastructure, affecting all services that depend on krb4 for secure authentication.
Mitigation strategies for this vulnerability require immediate implementation of protocol upgrades and cryptographic configuration changes within the krb5 distribution. Organizations should disable krb4 support entirely and migrate to Kerberos version 5 implementations that properly handle cryptographic operations and key management. System administrators must ensure that all krb4 services are configured to use strong cryptographic algorithms and that ticket validation procedures include proper integrity checks. The fix involves updating the krb5 distribution to versions that address the specific cryptographic weaknesses in the krb4 implementation, while also implementing network segmentation and monitoring to detect unauthorized ticket manipulation attempts. This vulnerability aligns with CWE-310 and follows attack patterns consistent with the MITRE ATT&CK framework's credential access techniques, specifically targeting the Kerberos authentication protocol's cryptographic foundations.