Zero-day vulnerability in Microsoft Office

Memory corruption
CVE-2015-2545

CVE-2015-2545 fuels around 17% of attacks in Microsoft Office.

Used to target organisations in China.

Vulnerability details

Advisory: SB2015090801 - Multiple vulnerabilities in Microsoft Office

Vulnerable component: Microsoft Office

CVE-ID: CVE-2015-2545

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-119 - Memory corruption

Description:

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

The vulnerability exists due to boundary error when parsing malformed images. A remote attacker can create a file containing a specially crafted image file, trick the victim into opening it, cause memory corruption and execute arbitrary code with privileges of the current user.

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

Note: the vulnerability was being actively exploited.

External links:

https://technet.microsoft.com/en-us/library/security/ms15-099
https://www.fireeye.com/content/dam/fireeye-www/blog/pdfs/twoforonefinal.pdf
http://pwc.blogs.com/cyber_security_updates/2016/05/exploring-cve-2015-2545-and-its-users.html
https://threatpost.com/apt-groups-finding-success-with-patched-microsoft-flaw/118298/
http://www.securityweek.com/year-old-office-vulnerabilities-most-popular-current-attacks
https://securelist.com/analysis/publications/74828/cve-2015-2545-overview-of-current-threats/
https://www.symantec.com/security_response/vulnerability.jsp?bid=76667
https://blogs.sophos.com/2016/07/18/cybercriminals-shift-their-tactics-for-microsoft-office-document...
https://www.threatconnect.com/blog/word-document-trojan-exploiting-cve/
http://www.itworldcanada.com/article/exploit-kits-now-adopting-recent-office-vulnerabilities-report/...
https://www.scmagazine.com/microsoft-fixes-several-bugs-on-patch-tuesday-two-being-actively-exploite...
http://blog.morphisec.com/exploit-bypass-emet-cve-2015-2545
http://news.softpedia.com/news/one-microsoft-office-exploit-has-become-very-popular-with-cyber-espio...
http://news.softpedia.com/news/ke3chang-is-back-and-it-s-targeting-indian-embassies-around-the-globe...

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.