Remote code execution in Microsoft Word



Published: 2018-10-26 | Updated: 2018-11-15
Risk Critical
Patch available NO
Number of vulnerabilities 1
CVE ID N/A
CWE ID CWE-20
Exploitation vector Network
Public exploit This vulnerability is being exploited in the wild.
Vulnerable software
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Microsoft Office
Client/Desktop applications / Office applications

Microsoft Word
Client/Desktop applications / Office applications

Vendor Microsoft

Security Advisory

UPDATED: 15.11.2018

Added information about active exploitation of the vulnerability in the wild, changed severity vulnerability from high to critical.

This vulnerability is being treated as of now as a zero-day.

1) Logic error

Risk: Critical

CVSSv3.1: 9.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H/E:H/RL:U/RC:C] [PCI]

CVE-ID: N/A

CWE-ID: CWE-20 - Improper Input Validation

Exploit availability: No

Description

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

The weakness exists due to a logical bug is revealed when embedding a video via the 'online video' feature. A remote attacker can embed a video inside a Word document, edit the XML file named document.xml, replace the video link with a crafted payload created by the attacker which opens Internet Explorer Download Manager with the embedded code execution file and execute arbitrary code with elevated privileges.

Successful exploitation of the vulnerability may result in system compromise.

Note: as of October 31, 2018 the vulnerability is being actively exploited in the wild.

Mitigation

Cybersecurity Help is currently unaware of any official solution to address this vulnerability.
To avoid the vulnerability users are recommended to block Word documents containing an embedded video.

Vulnerable software versions

Microsoft Office: 2013, 2016, 2019

Microsoft Word: 2013, 2016

CPE External links

https://blog.cymulate.com/abusing-microsoft-office-online-video
https://blog.trendmicro.com/trendlabs-security-intelligence/hide-and-script-inserted-malicious-urls-...

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 an attachment in an e-mail message.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.



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