CVE-2021-21958 : Security Advisory and Response

This article delves into the heap-based buffer overflow vulnerability in Hancom Office 2020 11.0.0.2353, known as CVE-2021-21958.

Understanding CVE-2021-21958

CVE-2021-21958 is a high-severity vulnerability found in the Hword HwordApp.dll functionality of Hancom Office 2020 11.0.0.2353. It can result in memory corruption and potential arbitrary code execution when a specially crafted file triggers the flaw.

What is CVE-2021-21958?

The vulnerability identified as CVE-2021-21958 is a heap-based buffer overflow in Hancom Office 2020 version 11.0.0.2353. Exploitation of this flaw could allow an attacker to execute arbitrary code by providing a malicious file.

The Impact of CVE-2021-21958

With a CVSS base score of 7.8, CVE-2021-21958 is rated as high severity. This vulnerability can have a significant impact on the confidentiality, integrity, and availability of the affected system.

Technical Details of CVE-2021-21958

The technical details of CVE-2021-21958 provide insight into the vulnerability's description, affected systems and versions, as well as the exploitation mechanism.

Vulnerability Description

A heap-based buffer overflow flaw in the Hword HwordApp.dll functionality of Hancom Office 2020 11.0.0.2353 can be exploited by a maliciously crafted file, leading to memory corruption and potential arbitrary code execution.

Affected Systems and Versions

Hancom Office 2020 version 11.0.0.2353 is specifically impacted by CVE-2021-21958 due to the presence of the heap-based buffer overflow vulnerability.

Exploitation Mechanism

By providing a specially-crafted malformed file, an attacker can trigger the heap-based buffer overflow vulnerability in Hancom Office 2020 11.0.0.2353, potentially allowing for arbitrary code execution.

Mitigation and Prevention

To address CVE-2021-21958, immediate steps must be taken to mitigate the vulnerability and prevent exploitation. Implementing long-term security practices and ensuring timely patching and updates are crucial.

Immediate Steps to Take

Users and organizations should update Hancom Office to a non-vulnerable version, apply patches provided by the vendor, and exercise caution when handling files from untrusted sources.

Long-Term Security Practices

Maintaining secure coding practices, conducting regular security assessments, and educating users on file security best practices can help prevent similar vulnerabilities in the future.

Patching and Updates

Regularly checking for updates from Hancom and promptly applying security patches is essential in safeguarding systems against CVE-2021-21958 and other potential threats.