CVE-2018-5736 Explained : Impact and Mitigation

A vulnerability in BIND versions 9.12.0 and 9.12.1 could allow an attacker to trigger an assertion failure by rapidly transferring a slave zone multiple times. This flaw may lead to the named process exiting, impacting servers running the vulnerable versions.

Understanding CVE-2018-5736

This CVE involves a specific issue in BIND that affects the zone database reference counting mechanism, potentially leading to a server crash under certain conditions.

What is CVE-2018-5736?

The vulnerability in BIND versions 9.12.0 and 9.12.1 allows an attacker with permission to initiate zone transfers to exploit a flaw in zone database reference counting. By triggering multiple rapid transfers of a slave zone, the attacker can cause an assertion failure, resulting in the named process exiting.

The Impact of CVE-2018-5736

The vulnerability poses a risk to servers running affected versions of BIND, potentially leading to a denial of service condition if exploited by an attacker with the necessary permissions to initiate zone transfers.

Technical Details of CVE-2018-5736

This section provides more in-depth technical insights into the vulnerability.

Vulnerability Description

The flaw in BIND's zone database reference counting can be exploited by triggering rapid transfers of a slave zone, leading to an assertion failure and subsequent server crash.

Affected Systems and Versions

Vulnerable Versions: BIND 9.12.0 and 9.12.1
Systems: Servers running the affected versions of BIND

Exploitation Mechanism

Attackers with permission to initiate zone transfers can exploit the vulnerability by triggering multiple rapid transfers of a slave zone.
By sending valid NOTIFY messages, attackers can cause the named process to exit after failing the assertion test.

Mitigation and Prevention

To address CVE-2018-5736 and enhance overall security, consider the following mitigation strategies:

Immediate Steps to Take

Update BIND to a patched version that addresses the vulnerability.
Monitor server logs for any unusual zone transfer activities.

Long-Term Security Practices

Regularly update BIND and other software components to mitigate potential vulnerabilities.
Implement network segmentation to limit the impact of potential attacks.

Patching and Updates

Apply patches provided by ISC or the relevant software vendor to fix the vulnerability and enhance server security.