ISC BIND nxdomain Redirect Feature Denial of Service Vulnerability [CVE-2019-6467]

CVE Number – CVE-2019-6467

A vulnerability in ISC BIND could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted system. The vulnerability is due to an error in the nxdomain-redirect feature of the affected software. An attacker could exploit this vulnerability by sending a recursive query request to the targeted system. A successful exploit could cause BIND to exit and halt service to other clients, resulting in a DoS condition. ISC.org has confirmed the vulnerability and released software updates.

Analysis

• To exploit this vulnerability, an attacker must send a recursive query request to the targeted system, making exploitation more difficult in environments that restrict network access from untrusted sources.

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

• ISC.org has released a security advisory at the following link: CVE-2019-6467: An error in the nxdomain redirect feature can cause BIND to exit with an INSIST assertion failure in query.c

Fixed Software

• ISC.org has released software updates at the following link: bind 9.12.4-P1, bind 9.14.1