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National Cyber Alert System
Technical Cyber Security Alert TA10-103C archive

Adobe Reader and Acrobat Vulnerabilities

Original release date: April 13, 2010
Last revised: --
Source: US-CERT

Systems Affected

  • Adobe Reader 9.3.1 and earlier 9.x versions
  • Adobe Reader 8.2.1 and earlier versions
  • Adobe Acrobat 9.3.1 and earlier 9.x versions
  • Adobe Acrobat 8.2.1 and earlier versions

Overview

Adobe has released Security Bulletin APSB10-09, which describes multiple vulnerabilities affecting Adobe Reader and Acrobat.


I. Description

Adobe Security Bulletin APSB10-09 describes a number of vulnerabilities affecting Adobe Reader and Acrobat. These vulnerabilities affect Reader and Acrobat 9.3.1 and earlier 9.x versions, and 8.2.1 and earlier versions.

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


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 document.


III. Solution

Update

Adobe has released updates to address this issue. Users are encouraged to read Adobe Security Bulletin APSB10-09 and update vulnerable versions of Adobe Reader and Acrobat.

Adobe does not offer standalone installers of Reader or Acrobat versions 9.3.2 or 8.2.2. For a fresh installation, first install Adobe Reader 9.3.0 or 8.2.0 and then use the automatic update feature or install the appropriate update referenced in APSB10-09.

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 documents

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 documents in the web browser

Preventing PDF documents 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 documents 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 documents from untrusted sources

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


IV. References


Feedback can be directed to US-CERT.

Produced 2010 by US-CERT, a government organization. Terms of use


Revision History

April 13, 2010: Initial release

Last updated April 13, 2010
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