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

ITS Advisory Number: 
2013-074
Date(s) Issued: 
Tuesday, August 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
BUSINESS
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.

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.

Actions: 
  • 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