MS-ISAC CYBERSECURITY ADVISORIES

MS-ISAC ADVISORY NUMBER:
2016-155

DATE(S) ISSUED:
10/11/2016

SUBJECT:
A Vulnerability in Microsoft Office Could Allow for Remote Code Execution (MS16-121)

OVERVIEW:

A vulnerability has been discovered in Microsoft Office, which could result in remote code execution if the user opens a specially crafted Rich Text File (“.rtf”). Successful exploitation of this vulnerability could result in an attacker gaining the same privileges as the logged on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.

THREAT INTELLIGENCE:

There are reports of this vulnerability being exploited in the wild.

SYSTEMS AFFECTED:

· Microsoft Office 2007, 2010, 2013, 2013 RT, 2016

· Microsoft Office for Mac 2011, Office 2016 for Mac

· Microsoft Office Compatibility Pack SP3

· Microsoft Word Viewer

· Microsoft Excel Viewer

· Microsoft PowerPoint Viewer

· Microsoft SharePoint Server 2007, 2010, 2013

· Microsoft Office Web Apps 2010, 2013

· Microsoft Office Online Server

RISK:

Government:

· Large and medium government entities:High

· Small government: Medium

Businesses:

· Large and medium business entities:High

· Small business entities:Medium

Home users: Low

TECHNICAL SUMMARY:

A memory corruption vulnerability has been discovered in Microsoft Office in the way it fails to properly handle objects in memory. This vulnerability could be exploited if a user opens a specially crafted Rich Text File (“.rtf”). An attacker who successfully exploited this vulnerability could run remote code in the context of the current user.(CVE-2016-7193)

Successful exploitation of this vulnerability could result in an attacker gaining the same privileges as the logged on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.

RECOMMENDATIONS:

We recommend the following actions be taken:

· Apply appropriate patches provided by Microsoft to vulnerable systems immediately after appropriate testing.

· Run all software as a non-privileged user (one without administrative privileges) to diminish the effects of a successful attack.

· Remind users not to visit websites or follow links provided by unknown or untrusted sources.

· Inform and educate users regarding the threats posed by hypertext links contained in emails or attachments especially from untrusted sources.

· Apply the Principle of Least Privilege to all systems and services.

REFERENCES:

Microsoft:

https://technet.microsoft.com/en-us/library/security/ms16-121.aspx

CVE:

http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-7193