MS-ISAC CYBERSECURITY ADVISORIES

MS-ISAC ADVISORY NUMBER:
2015-135

DATE(S) ISSUED:
11/10/2015

SUBJECT:
Multiple Vulnerabilities in Microsoft Office Could Allow Remote Code Execution (MS15-116)

OVERVIEW:

Multiple vulnerabilities have been discovered in Microsoft Office. The most severe of these vulnerabilities could allow remote code execution. Successful exploitation of these vulnerabilities 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.

THREAT INTELLIGENCE:

There are no reports of these vulnerabilities being exploited in the wild. One elevation of privilege vulnerability (CVE-2015-2503) has been publicly disclosed.

SYSTEMS AFFECTED:

  • Microsoft Excel 2007

  • Microsoft Excel 2010

  • Microsoft Excel for Mac 2011

  • Microsoft Excel 2013, RT

  • Microsoft Excel 2016

  • Microsoft Excel 2016 for Mac

  • Microsoft SharePoint Server 2007

  • Microsoft SharePoint Server 2010

  • Microsoft SharePoint Server 2013

  • Microsoft Office Web Apps 2010

  • Microsoft Office Web Apps 2013

  • Skype for Business 2016

  • Microsoft Lync 2013 (Skype for Business)

 

RISK:

Government:

  • Large and medium government entities: High

  • Small government entities: High

 

Businesses:

  • Large and medium business entities: High

  • Small business entities: High

 

Home users: High

 

TECHNICAL SUMMARY:

Seven vulnerabilities have been discovered in Microsoft Office. The most severe of these vulnerabilities could allow remote code execution if a user opens a specially crafted Microsoft Office file, and can be exploited via email or web. An attacker who successfully exploited these vulnerabilities could run arbitrary code in the context of the current user. 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. Details of these vulnerabilities are as follows:

  • Five memory corruption vulnerabilities exist in the way Office handles objects in memory (CVE-2015-6038; CVE-2015-6091; CVE-2015-6092; CVE-2015-6093; CVE-2015-6094)

  • One Microsoft Office Elevation of Privilege Vulnerability (CVE-2015-2503)

  • One Microsoft Outlook for Mac Spoofing Vulnerability (CVE-2015-6123)

 

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 un-trusted websites or follow links provided by unknown or un-trusted sources.Unless there is a business need to do otherwise, consider disabling XBAPs in Internet Explorer 6, 7, 8. By default, newer versions of Internet Explorer no longer allow XBAPs to run on Internet websites, but they still function in the Local Intranet and Trusted Zones.

 

REFERENCES:

Microsoft:
https://technet.microsoft.com/en-us/library/security/MS15-116

CVE:
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-6038
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-6091
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-6092
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-6093
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-6094
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2503
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-6123