Adobe Reader and Acrobat Affected by Multiple Vulnerabilities

• Adobe Reader 9.3.4 and earlier versions for Windows, Macintosh, and UNIX
• Adobe Acrobat 9.3.4 and earlier versions for Windows and Macintosh
• Adobe Reader 8.2.4 and earlier versions for Windows, Macintosh, and UNIX
• Adobe Acrobat 8.2.4 and earlier versions for Windows and Macintosh

Adobe has released Security Bulletin APSB10-21, which describes multiple vulnerabilities affecting Adobe Reader and Acrobat.

Adobe Security Bulletin APSB10-21 describes a number of vulnerabilities affecting Adobe Reader and Acrobat. These vulnerabilities affect Reader and Acrobat 9.3.4, earlier 9.x versions, 8.2.4, and earlier 8.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.

Additional information is available in US-CERT Vulnerability Note VU#491991.

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.

Update

Adobe has released updates to address this issue. Users are encouraged to read Adobe Security Bulletin APSB10-21 and update vulnerable versions of Adobe Reader and Acrobat.

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 feature 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.

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.

October 06, 2010: Initial release