CVE-2021-43304 : Exploit Details and Defense Strategies

A heap buffer overflow vulnerability in Clickhouse's LZ4 compression codec poses a serious threat when processing malicious queries.

Understanding CVE-2021-43304

This CVE highlights a critical vulnerability in Clickhouse's LZ4 compression codec that could be exploited to trigger a heap buffer overflow.

What is CVE-2021-43304?

The vulnerability occurs due to insufficient verification in the LZ4::decompressImpl loop, specifically in the arbitrary copy operation wildCopy<copy_amount>(op, ip, copy_end), leading to potential buffer limits overreach.

The Impact of CVE-2021-43304

Attackers could craft malicious queries to trigger a heap buffer overflow, potentially leading to remote code execution or denial of service.
The vulnerability affects Yandex's Clickhouse database, specifically versions prior to 21.10.2.15-stable.

Technical Details of CVE-2021-43304

This section delves into the technical aspects of the CVE.

Vulnerability Description

The issue arises from unchecked copy operations in the LZ4 compression codec, allowing for buffer overflow attacks when processing specially crafted queries.

Affected Systems and Versions

Vendor: Yandex
Product: Clickhouse
Affected Versions: Versions prior to 21.10.2.15-stable (custom version type)

Exploitation Mechanism

Malicious queries can exploit the vulnerability by exceeding the buffer limits during the LZ4::decompressImpl loop operation.

Mitigation and Prevention

Protecting against CVE-2021-43304 requires immediate action and long-term security practices.

Immediate Steps to Take

Update Clickhouse to version 21.10.2.15-stable or newer to mitigate the vulnerability.
Implement network segmentation to limit the impact of potential attacks.

Long-Term Security Practices

Regularly monitor for security advisories and update systems promptly.
Conduct security assessments and penetration testing to uncover underlying vulnerabilities.

Patching and Updates

Stay informed about security patches and updates provided by Yandex for Clickhouse to address known vulnerabilities.