CVE-2022-2031 in Samba
Summary
by MITRE • 08/25/2022
A flaw was found in Samba. The security vulnerability occurs when KDC and the kpasswd service share a single account and set of keys, allowing them to decrypt each other's tickets. A user who has been requested to change their password, can exploit this flaw to obtain and use tickets to other services.
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Analysis
by VulDB Data Team • 05/24/2026
This vulnerability exists within the Samba implementation of Kerberos authentication services, specifically affecting the Key Distribution Center and kpasswd service components. The flaw stems from a critical design oversight where both services utilize identical account credentials and cryptographic keys, creating an unauthorized cross-decryption capability between otherwise separate security domains. When a user attempts to change their password through the kpasswd service, the compromised authentication context enables exploitation of Kerberos ticket decryption mechanisms that should remain isolated between services. This represents a fundamental breakdown in the principle of least privilege and separation of concerns within the Kerberos authentication framework, where the shared credential model creates an attack vector that bypasses normal security boundaries.
The technical exploitation occurs through the manipulation of Kerberos ticket-granting tickets and service tickets that are encrypted using the same cryptographic keys. When the kpasswd service processes password change requests, it operates under the same key material as the KDC, allowing an attacker to intercept and decrypt tickets that should be protected by different cryptographic contexts. This vulnerability specifically impacts the Kerberos v5 protocol implementation within Samba servers and affects systems where the kpasswd service and KDC share the same principal account. The flaw enables a technique known as ticket decryption and reuse, which falls under the broader category of credential compromise and privilege escalation attacks. This weakness is classified as a violation of the cryptographic key separation principle and represents a direct threat to the integrity of the Kerberos authentication infrastructure.
The operational impact of this vulnerability extends beyond simple credential theft to encompass full compromise of the Kerberos authentication system within affected Samba environments. Attackers can leverage this flaw to obtain valid tickets for services that they should not normally access, potentially enabling lateral movement throughout the network infrastructure. The vulnerability creates an unauthorized path for privilege escalation and can result in complete compromise of authentication services, affecting not just individual user accounts but entire organizational security domains. Systems running Samba with Kerberos authentication that have not applied the relevant patches are particularly vulnerable to this attack vector, which can be executed remotely without requiring prior authentication. This weakness significantly undermines the trust model that Kerberos relies upon for secure authentication and authorization.
Mitigation strategies for this vulnerability require immediate patching of affected Samba installations to ensure that KDC and kpasswd services operate with separate and distinct credential sets. Organizations should implement proper key separation practices and ensure that each service utilizes unique cryptographic keys and account principals. Network segmentation and monitoring of Kerberos traffic can help detect anomalous authentication patterns that may indicate exploitation attempts. The implementation of additional security controls such as Kerberos ticket auditing, privilege monitoring, and regular credential rotation should be enforced. This vulnerability aligns with ATT&CK technique T1550.003 for use of Kerberoasting and T1550.001 for use of Kerberos authentication, making it particularly dangerous in environments where Kerberos is widely deployed. Organizations should also consider implementing principle of least privilege controls and ensuring that the kpasswd service operates with minimal required privileges to reduce the potential impact of credential compromise.