CVE-2018-5733 : Security Advisory and Response

A 32-bit reference counter in the DHCP server can be overwhelmed by a malicious client, potentially leading to a denial of service. This CVE affects ISC DHCP versions 4.1.0 through 4.1-ESV-R15, 4.2.0 through 4.2.8, 4.3.0 through 4.3.6, and 4.4.0.

Understanding CVE-2018-5733

This CVE involves a vulnerability in ISC DHCP that can be exploited by a malicious client to crash the DHCP server by sending an excessive amount of traffic.

What is CVE-2018-5733?

A 32-bit reference counter overflow in ISC DHCP can be triggered by a malicious client flooding the server with traffic, potentially causing a denial of service.

The Impact of CVE-2018-5733

CVSS Base Score: 5.9 (Medium)
Attack Vector: Network
Attack Complexity: High
Availability Impact: High
Successful exploitation may exhaust memory and crash the DHCP server, leading to a denial of service.

Technical Details of CVE-2018-5733

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The vulnerability involves a 32-bit reference counter overflow in ISC DHCP due to excessive traffic from a malicious client.

Affected Systems and Versions

ISC DHCP versions 4.1.0 to 4.1-ESV-R15
ISC DHCP versions 4.2.0 to 4.2.8
ISC DHCP versions 4.3.0 to 4.3.6
ISC DHCP version 4.4.0

Exploitation Mechanism

Malicious client sends an excessive amount of traffic to overwhelm the reference counter in the DHCP server.

Mitigation and Prevention

Protect your systems from CVE-2018-5733 with the following steps:

Immediate Steps to Take

Upgrade to the patched release closest to your current DHCP version.

Long-Term Security Practices

Monitor network traffic for anomalies that could indicate a potential attack.
Implement rate limiting to prevent overwhelming the DHCP server.

Patching and Updates

Apply the following patches:
DHCP 4.1-ESV-R15-P1
DHCP 4.3.6-P1
DHCP 4.4.1