CVE-2022-2393: Pki-core Auth Bypass Vulnerability

CVE-2022-2393 Overview

A flaw was found in pki-core, which could allow a user to get a certificate for another user identity when directory-based authentication is enabled. This flaw allows an authenticated attacker on the adjacent network to impersonate another user within the scope of the domain, but they would not be able to decrypt message content. This authorization bypass vulnerability poses significant risks to organizations relying on PKI infrastructure for identity management and certificate-based authentication.

Critical Impact

Authenticated attackers on adjacent networks can obtain certificates for other user identities, enabling impersonation attacks within the domain scope.

Affected Products

• pki-core_project pki-core
• Red Hat Certificate System 9.0 and 10.0
• Red Hat Enterprise Linux 6.0, 7.0, 8.0, and 9.0

Discovery Timeline

• 2022-07-14 - CVE-2022-2393 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-2393

Vulnerability Analysis

This vulnerability represents an authorization bypass flaw (CWE-285: Improper Authorization) in the pki-core certificate management system. The issue manifests specifically when directory-based authentication is enabled, creating a scenario where the certificate issuance process fails to properly validate that the requesting user is authorized to obtain a certificate for the identity specified in the request.

The attack requires adjacent network access, meaning the attacker must be on the same network segment as the PKI infrastructure. Additionally, the attacker must possess valid credentials (low-privilege authentication), which they can then leverage to request certificates for other user identities within the domain.

While the attacker can successfully impersonate other users by obtaining certificates in their name, the vulnerability does not grant access to decrypt existing encrypted message content belonging to the impersonated user. This limitation exists because the attacker generates new key pairs during the certificate request process rather than obtaining the victim's private keys.

Root Cause

The root cause of this vulnerability lies in improper authorization checks within the pki-core certificate request handling logic when directory-based authentication is configured. The system fails to adequately verify that the authenticated user making a certificate request is actually authorized to receive a certificate for the specified subject identity.

When directory-based authentication is enabled, the PKI system trusts the directory service for authentication but does not properly enforce authorization policies that should restrict users to only requesting certificates for their own identities.

Attack Vector

The attack vector requires adjacent network access, meaning an attacker must be positioned on the same local network segment as the vulnerable PKI infrastructure. The attack flow involves:

1. The attacker authenticates to the PKI system using their own valid credentials
2. The attacker submits a certificate signing request (CSR) specifying another user's identity information
3. Due to the authorization bypass, the PKI system processes the request without verifying the requester's authorization to obtain a certificate for that identity
4. The attacker receives a valid certificate for the victim user's identity
5. The attacker can now use this certificate to impersonate the victim for authentication purposes within the domain

The vulnerability affects confidentiality by allowing unauthorized access to resources protected by certificate-based authentication, though the attacker cannot decrypt existing encrypted communications belonging to the impersonated user.

Detection Methods for CVE-2022-2393

Indicators of Compromise

• Certificate issuance logs showing users receiving certificates with subject names not matching their authenticated identity
• Unusual patterns of certificate requests from single user accounts for multiple different identities
• Authentication events using certificates where the certificate subject does not match expected user principal mappings
• Directory audit logs showing certificate attribute queries for users other than the authenticated requestor

Detection Strategies

• Implement audit logging for all certificate issuance events, correlating the authenticated user identity with the certificate subject
• Monitor for certificate requests where the authenticated user DN differs from the requested certificate subject DN
• Deploy network segmentation monitoring to detect unauthorized adjacent network access to PKI infrastructure
• Review PKI system logs for anomalous certificate request patterns indicating potential exploitation attempts

Monitoring Recommendations

• Enable verbose logging on Certificate Authority (CA) servers to capture full certificate request details including authenticated user and requested subject
• Configure SIEM alerts for certificate issuance events where authentication identity mismatches certificate subject
• Monitor directory service logs for unusual LDAP queries related to user certificate attributes
• Implement periodic audits of issued certificates to identify any certificates with potentially fraudulent subject identities

How to Mitigate CVE-2022-2393

Immediate Actions Required

• Review pki-core configuration and disable directory-based authentication if not strictly required until patches are applied
• Restrict network access to PKI infrastructure to only authorized systems and administrators
• Audit recently issued certificates to identify any potentially fraudulent certificates that may have been obtained through exploitation
• Implement additional authorization controls at the application or network layer to validate certificate requests

Patch Information

Organizations should consult the Red Hat Bug Report #2101046 for the latest patch information and remediation guidance. Red Hat Enterprise Linux and Certificate System users should apply available security updates from Red Hat's official repositories. Ensure all affected pki-core installations are updated to patched versions as they become available.

Workarounds

• Disable directory-based authentication in pki-core if the feature is not essential to operations
• Implement strict network segmentation to limit adjacent network access to PKI infrastructure
• Deploy additional authorization middleware that validates certificate subject matches authenticated user identity before forwarding requests to the CA
• Enable manual approval workflows for certificate issuance to allow human verification of certificate requests
• Configure firewall rules to restrict access to PKI services from only known, trusted network segments