10 - TA11-350A

Adobe has released Security Bulletin APSB11-30, which describes multiple vulnerabilities affecting Adobe Reader and Acrobat.

I. Description

Adobe Security Bulletin APSB11-30 and Adobe Security Advisory APSA11-04 describe a number of vulnerabilities affecting Adobe Reader and Acrobat. These vulnerabilities affect Reader and Acrobat
9.4.6 and earlier 9.x versions. These vulnerabilities also affect Reader X and Acrobat X 10.1.1 and earlier 10.x versions.

An attacker could exploit these vulnerabilities by convincing a user to open a specially crafted PDF file. The Adobe Reader browser plug-in, which can automatically open PDF documents hosted on a website, is available for multiple web browsers and operating systems.

Adobe Reader X and Adobe Acrobat X will be patched in the next quarterly update scheduled for January 10, 2012.

Additional details for the U3D memory corruption vulnerability can be found in US-CERT Vulnerability Note VU#759307.

II. Impact

These vulnerabilities could allow a remote attacker to execute arbitrary code, write arbitrary files or folders to the file system, escalate local privileges, or cause a denial of service on an affected system as the result of a user opening a malicious PDF file.

III. Solution

Update Reader

Adobe has released updates to address this issue. Users are encouraged to read Adobe Security Bulletin APSB11-30 and update vulnerable versions of Adobe Reader and Acrobat.

In addition to updating, please consider the following mitigations.

Disable Flash in Adobe Reader and Acrobat

Disabling Flash in Adobe Reader will mitigate attacks that rely on Flash content embedded in a PDF file. Disabling 3D & Multimedia support does not directly address the vulnerability, but it does provide additional mitigation and results in a more user-friendly error message instead of a crash. To disable Flash and 3D &
Multimedia support in Adobe Reader 9, delete, rename, or remove access to these files:

Microsoft Windows
"%ProgramFiles%\Adobe\Reader 9.0\Reader\authplay.dll"
"%ProgramFiles%\Adobe\Reader 9.0\Reader\rt3d.dll"

Apple Mac OS X
"/Applications/Adobe Reader 9/Adobe Reader.app/Contents/Frameworks/AuthPlayLib.bundle"
"/Applications/Adobe Reader 9/Adobe Reader.app/Contents/Frameworks/Adobe3D.framework"

GNU/Linux (locations may vary among distributions)
"/opt/Adobe/Reader9/Reader/intellinux/lib/libauthplay.so"
"/opt/Adobe/Reader9/Reader/intellinux/lib/librt3d.so"

File locations may be different for Adobe Acrobat or other Adobe products that include Flash and 3D & Multimedia support. Disabling these plugins will reduce functionality and will not protect against Flash content that is hosted on websites. Depending on the update schedule for products other than Flash Player, consider leaving Flash and 3D & Multimedia support disabled unless they are absolutely required.

Disable JavaScript in Adobe Reader and Acrobat

Disabling JavaScript may prevent some exploits from resulting in code execution. Acrobat JavaScript can be disabled using the Preferences menu (Edit -> Preferences -> JavaScript; uncheck Enable Acrobat JavaScript).

Adobe provides a framework to blacklist specific JavaScipt APIs. If JavaScript must be enabled, this framework may be useful when specific APIs are known to be vulnerable or used in attacks.

Prevent Internet Explorer from automatically opening PDF files

The installer for Adobe Reader and Acrobat configures Internet Explorer to automatically open PDF files without any user interaction. This behavior can be reverted to a safer option that prompts the user by importing the following as a .REG file:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\AcroExch.Document.7]
"EditFlags"=hex:00,00,00,00

Disable the display of PDF files in the web browser

Preventing PDF files from opening inside a web browser will partially mitigate this vulnerability. If this workaround is applied, it may also mitigate future vulnerabilities.

To prevent PDF files from automatically being opened in a web browser, do the following:

1. Open Adobe Acrobat Reader.
2. Open the Edit menu.
3. Choose the Preferences option.
4. Choose the Internet section.
5. Uncheck the "Display PDF in browser" checkbox.

Remove or restrict access to 3difr.x3d

By removing or restricting access to the 3difr.x3d file, Adobe Reader and Acrobat will fail to render U3D content, which helps to mitigate this vulnerability. PDF documents that use the PRC format for 3D content will continue to function on Windows and Linux platforms.

To disable U3D support in Adobe Reader 9 on Microsoft Windows, delete or rename this file:

"%ProgramFiles%\Adobe\Reader 9.0\Reader\plug_ins3d\3difr.x3d"

For Apple Mac OS X, delete or rename this directory:

"/Applications/Adobe Reader 9/Adobe Reader.app/Contents/Frameworks/Adobe3D.framework"

For GNU/Linux, delete or rename this file (locations may vary among distributions):

"/opt/Adobe/Reader9/Reader/intellinux/plug_ins3d/3difr.x3d"

File locations may be different for Adobe Acrobat or other Adobe products or versions.

Do not access PDF files from untrusted sources

Do not open unfamiliar or unexpected PDF files, particularly those hosted on websites or delivered as email attachments. Please see Cyber Security Tip ST04-010.