Zero-day vulnerability in Hancom Office

Type confusion
CVE-2015-6585

Trojan.Volgmer.B. Attackers from North Korea exploited the vulnerability HANGMAN in a word processor popular with the South Korea's government to steal the documents and upload them to a C&C server.
North Korea attack in June dubbed "Macktruck".

Vulnerability details

Advisory: SB2015090701 - Remote code execution in Hangul Word Processor

Vulnerable component: Hancom Office

CVE-ID: CVE-2015-6585

CVSSv3 score: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H/E:H/RL:O/RC:C

CWE-ID: CWE-843 - Type confusion

Description:

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

The vulnerability exists due to type confusion error. A remote attacker can create a specially crafted HWPX file containing a set of directories and XML files, trick the victim into opening it, cause memory corruption and execute arbitrary code with privileges of the current user.

Successful exploitation of this vulnerability may result in arbitrary code execution on the vulnerable system.

Note: this vulnerability is being actively exploited.

Known APT campaigns:

Macktruck attack

The hackers performed the operation with the help of тАЬHangmanтАЭ malware. FireEye suspects North Korea of attack against South Korea.

External links:

https://www.fireeye.com/content/dam/fireeye-www/global/en/blog/threat-research/FireEye_HWP_ZeroDay.p...
https://www.fireeye.com/blog/threat-research/2015/09/zero-day_hwp_exploit.html
http://www.pcworld.com/article/2982577/north-korea-is-likely-behind-attacks-exploiting-a-korean-word...
http://www.hancom.com/index.jsp
http://securityaffairs.co/wordpress/40029/hacking/north-kore-0-day-hangul.html
https://c0deman.wordpress.com/2015/11/02/hangul-word-processor-hwp-zero-day-possible-ties-to-north-k...
http://www.securityweek.com/north-korea-suspected-using-zero-day-attack-south
http://www.theregister.co.uk/2015/09/10/north_korea_exploits_zero_day_in_seouls_favourite_word_doc/
http://www.spamfighter.com/News-19851-North-Korea-Probably-Main-Architect-of-Cyberattacks-in-South-K...
http://www.ehackingnews.com/2015/09/researchers-say-north-korea-behind.html


About zero-day vulnerabilities

Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.

Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.