Heimdal Anonymous PKINIT PA-PKINIT-KX Vulnerability [CVE-2019-12098]

CVE number – CVE-2019-12098

A vulnerability in the client side of Heimdal could allow an unauthenticated, remote attacker to conduct a man-in-the-middle attack against a user on a targeted system.

The vulnerability exists because the krb5_init_creds_step function, as defined in the lib/krb5/init_creds_pw.c source code file of the affected software, does not verify the PA-PKINIT-KX key exchange when anonymous PKINIT is used. An attacker could exploit this vulnerability to conduct a man-in-the-middle attack. A successful exploit could allow the attacker to access sensitive information or modify communications between a targeted user communicating with another system. 

Heimdal has confirmed the vulnerability and released software updates.

Analysis

• To exploit this vulnerability, the attacker may need access to the same internal, trusted network as the targeted system. This access requirement may reduce the likelihood of a successful exploit.

Safeguards

• Administrators are advised to apply the appropriate updates.
  
  Administrators are advised to allow only trusted users to have network access.
  
  Administrators are advised to run both firewall and antivirus applications to minimize the potential of inbound and outbound threats.
  
  Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
  
  Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
  
  Administrators are advised to monitor affected systems.

Vendor Announcements

• Heimdal has released release notes at the following link: Heimdal 7.6.0 – Security Release

Fixed Software

• Heimdal has released software updates at the following link: Heimdal 7.6.0