Remote code execution in Hancom Office 2020

1) Stack-based buffer overflow

EUVDB-ID: #VU60679

Risk: High

CVSSv3.1: 8.1 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:U/RC:C]

CVE-ID: CVE-2021-21958

CWE-ID: CWE-121 - Stack-based buffer overflow

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error in the Hword HwordApp.dll functionality. A remote unauthenticated attacker can use a specially crafted file, trigger stack-based buffer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Cybersecurity Help is currently unaware of any official solution to address this vulnerability.

Vulnerable software versions

Hancom Office: 11.0.0.2353

External links

http://talosintelligence.com/vulnerability_reports/TALOS-2021-1386

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to trick the victim to visit a specially crafted website or open a file.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.