The following cyber advisory was issued by the New York State Office of Information Technology Services and is intended for State government entities. The information may or may not be applicable to the general public and, accordingly, the State does not warrant its use for any specific purposes.

ITS ADVISORY NUMBER:
2013-074

DATE(S) ISSUED:
8/13/2013

SUBJECT:
Vulnerabilities in Microsoft Exchange Server Could Allow Remote Code Execution (MS13-061)

OVERVIEW:

Multiple vulnerabilities have been reported in Microsoft Exchange Server WebReady Document viewing  and the Data Loss Prevention (DLP) feature that could allow remote code execution. Microsoft Exchange provides email, calendar, and contacts for corporate environments. MS Exchange Server WebReady document viewing is a feature that allows Outlook Web Access (OWA) users to view attachments such as Microsoft Office documents within the browser. Exploitation of these vulnerabilities could occur by sending an email with a specially crafted file to a user on an affected Exchange server

Successful exploitation could allow an attacker to run arbitrary code within the context of the LocalService account on the affected Microsoft Exchange Server. Depending on the privileges associated with the account, an attacker could install programs; view, change, or delete data; or create new accounts with full user rights.

SYSTEMS AFFECTED:

  • Microsoft Exchange Server 2007
  • Microsoft Exchange Server 2010
  • Microsoft Exchange Server 2013

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

DESCRIPTION:

Multiple vulnerabilities have been discovered in Microsoft Exchange Server WebReady Document Viewing and the Data Loss Prevention feature. These vulnerabilities could allow remote code execution in the security context of the Filtering Management service if a specially crafted message is received by the Exchange server. WebReady is enabled by default.

These issues exist due to vulnerabilities contained within libraries of Oracle Outside In, which are used when handling and rendering unstructured document formats. If disabled, OWA users may not be able to preview the content of email attachments.

To exploit these vulnerabilities, an attacker sends  a specially crafted file to the Exchange server or user on a vulnerable version of Microsoft Exchange. When the user opens the document within their browser, the specially crafted file runs within the privilege context of the LocalService account on the Microsoft Exchange Server. The LocalService account by default has limited system and file system privileges and sends only anonymous credentials over the network.

Successful exploitation could allow an attacker to run arbitrary code within the context of the LocalService account on the affected Microsoft Exchange Server. Depending on the privileges associated with the account, an attacker could install programs; view, change, or delete data; or create new accounts with full user rights.

RECOMMENDATIONS:
We recommend the following actions be taken:

  • Apply appropriate patches provided by Microsoft to vulnerable systems immediately after appropriate testing.
  • Evaluate the relative need for WebReady viewing. Disable if deemed non-essential.
  • Apply the principle of Least Privilege to all services
  • Remind users not to open email attachments from unknown users or suspicious emails from trusted sources.

REFERENCES:

Microsoft:
https://technet.microsoft.com/en-us/security/bulletin/ms13-061

CVE:
http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-3781
http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-3776
http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-2393

Deborah A. Snyder

Acting Chief Information Security Officer


 

Cyber Security

GIS