Public Vulnerability Reports

Apple OfficeImport Framework Excel Memory Corruption Vulnerability

03.21.11

BACKGROUND

The OfficeImport framework is an API used by Apple's mobile devices, including the iPod Touch, iPhone, and iPad. The framework is used to parse and display Microsoft Office file formats, such as Excel, Word, and PowerPoint. The OfficeImport framework is used by several applications, including MobileMail and MobileSafari. Both of these applications are attack vectors for this vulnerability. For more information, see the vendor's site found at the following link.

http://www.apple.com/iphone/softwareupdate/

DESCRIPTION

Remote exploitation of a memory corruption vulnerability in Apple Inc.'s OfficeImport framework could allow an attacker to execute arbitrary code with the privileges of the current user.

The vulnerability occurs when parsing an Excel file with a certain maliciously constructed record. This record is used to describe a formula that is shared between multiple cells. In this record, the 'formula' field is used to specify the formula used. By corrupting certain opcodes within this formula it is possible to trigger a memory corruption vulnerability. This can lead to the execution of arbitrary code.

ANALYSIS

Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user opening the file. To exploit this vulnerability, an attacker has several attack vectors. The most dangerous vector is through MobileSafari, which will automatically open and parse Office files embedded in Web pages. This behavior is similar to Microsoft Office 2000 in that it enables drive-by style attacks without any user-interaction beyond visiting a Web page (no file open dialog is displayed, the file is simply opened). Additionally, an attacker can e-mail a targeted user and attach a malicious file. The user will then have to view the e-mail and attachment with MobileMail to trigger the vulnerability.

DETECTION

iDefense has confirmed the existence of this vulnerability in OfficeFramework running on the following devices:

iPod Touch, IOS 3.1.3 iPad, IOS 3.2.2

Apple has reported Mac OS X and OS X Server 10.6 through 10.6.6 vulnerable.

WORKAROUND

iDefense is currently unaware of any workaround for this issue.

VENDOR RESPONSE

Apple Inc. has released patches which addresses this issue. For more information, consult their advisory at the following URL:

http://support.apple.com/kb/HT4581

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2011-0184 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems.

DISCLOSURE TIMELINE

01/07/2011 Initial Vendor Notification
01/07/2011 Initial Vendor Reply
03/21/2011 Coordinated Public Disclosure

CREDIT

This vulnerability was reported to iDefense by Tobias Klein.

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LEGAL NOTICES

Copyright © 2011 Verisign, Inc.

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Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.