CVE-2010-1323 in Kerberos
Summary
by MITRE
MIT Kerberos 5 (aka krb5) 1.3.x, 1.4.x, 1.5.x, 1.6.x, 1.7.x, and 1.8.x through 1.8.3 does not properly determine the acceptability of checksums, which might allow remote attackers to modify user-visible prompt text, modify a response to a Key Distribution Center (KDC), or forge a KRB-SAFE message via certain checksums that (1) are unkeyed or (2) use RC4 keys.
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Analysis
by VulDB Data Team • 10/06/2021
The vulnerability described in CVE-2010-1323 affects MIT Kerberos 5 implementations across multiple versions including 1.3.x through 1.8.3, representing a critical weakness in the cryptographic integrity verification mechanisms of the Kerberos authentication system. This flaw stems from improper checksum validation logic that fails to adequately assess the acceptability of checksums used in Kerberos protocol communications. The vulnerability specifically targets the KDC (Key Distribution Center) and affects the KRB-SAFE message format, which is designed to provide integrity protection for messages exchanged between Kerberos clients and servers. The issue manifests when the system processes checksums that are either unkeyed or utilize RC4 encryption keys, creating opportunities for attackers to manipulate authentication flows without proper authorization.
The technical exploitation of this vulnerability occurs through manipulation of checksum values in Kerberos messages, allowing attackers to alter user-visible prompt text during authentication processes. This weakness enables malicious actors to inject false information into authentication dialogs, potentially misleading users about the legitimacy of their authentication attempts. Additionally, attackers can modify responses to KDC queries, which may lead to unauthorized access to resources or disruption of legitimate authentication flows. The vulnerability also permits forgery of KRB-SAFE messages, which are specifically designed to provide integrity protection for sensitive data exchanges within the Kerberos framework. The root cause lies in the insufficient validation of checksum properties, particularly when dealing with unkeyed checksums or those employing RC4 encryption, which are inherently weaker cryptographic primitives.
From an operational impact perspective, this vulnerability compromises the fundamental security guarantees provided by Kerberos authentication systems. Organizations relying on these Kerberos versions face risks of credential theft, unauthorized access to protected resources, and potential elevation of privileges within their authentication domains. The ability to modify user prompts creates social engineering opportunities where attackers can manipulate user perceptions of legitimate authentication processes, while the KDC response modification capabilities enable more sophisticated attack vectors targeting the core authentication infrastructure. The forgery of KRB-SAFE messages represents a particularly dangerous aspect as it undermines the integrity protection mechanisms designed to prevent tampering with sensitive authentication data. This vulnerability affects the trust model of Kerberos implementations and can lead to cascading security failures within environments that depend on Kerberos for authentication services.
Mitigation strategies for CVE-2010-1323 should prioritize immediate patching of affected Kerberos versions to the latest available releases that address the checksum validation issues. Organizations must ensure that all Kerberos implementations are updated to versions that properly validate checksum acceptability, particularly focusing on eliminating support for unkeyed checksums and RC4-based key usage. Network segmentation and monitoring should be implemented to detect anomalous checksum patterns in Kerberos communications, as this vulnerability may be exploited in ways that are difficult to distinguish from legitimate protocol variations. Security teams should also consider implementing additional authentication layers or protocols that do not rely on vulnerable Kerberos checksum mechanisms, particularly for high-value assets. The vulnerability aligns with CWE-310 (Cryptographic Issues) and can be mapped to ATT&CK technique T1550.003 (Use Alternate Authentication Material) as it enables attackers to manipulate authentication flows through checksum manipulation. Organizations should also review their Kerberos configuration policies to ensure that only strong cryptographic algorithms are permitted in checksum operations, and implement regular security assessments to identify potential exploitation attempts targeting these authentication weaknesses.