CVE-2022-2929 : Exploit Details and Defense Strategies

In this article, we will discuss CVE-2022-2929, a vulnerability in ISC DHCP that could lead to a memory leak due to crafted DHCP packets with FQDN labels longer than 63 bytes.

Understanding CVE-2022-2929

This section covers the details and impact of the CVE-2022-2929 vulnerability.

What is CVE-2022-2929?

CVE-2022-2929 affects ISC DHCP versions 1.0 through versions before 4.1-ESV-R16-P2 and versions 4.2 through versions before 4.4.3.-P1. It allows an attacker with access to a DHCP server to send crafted DHCP packets, leading to a memory leak by causing the server to run out of memory.

The Impact of CVE-2022-2929

The vulnerability can result in a denial of service (DoS) condition on the affected DHCP server, impacting its availability.

Technical Details of CVE-2022-2929

In this section, we delve into the technical aspects of the CVE-2022-2929 vulnerability.

Vulnerability Description

The issue originates in the

fqdn_universe_decode()

function, which allocates buffer space for FQDN data in DHCP packets. If labels longer than 63 bytes are included, it triggers a memory leak.

Affected Systems and Versions

ISC DHCP versions 1.0 through 4.4.3 and versions 4.1-ESV-R1 through 4.1-ESV-R16-P1 are impacted by this vulnerability.

Exploitation Mechanism

An attacker can exploit this by sending specially crafted DHCP packets to the server, leading to memory exhaustion.

Mitigation and Prevention

This section focuses on steps to mitigate and prevent exploitation of CVE-2022-2929.

Immediate Steps to Take

Consider restarting DHCP servers periodically as a temporary workaround against prolonged packet sending.

Long-Term Security Practices

Regularly update and patch ISC DHCP to the latest secure versions to eliminate this vulnerability.

Patching and Updates

Upgrade to patched releases, such as 4.4.3-P1 or 4.1-ESV-R16-P2, which can be obtained from the official ISC website.