US-CERT Technical Cyber Security Alert TA09-161A -- Adobe Acrobat and Reader Vulnerabilities

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National Cyber Alert System

Technical Cyber Security Alert TA09-161A

Adobe Acrobat and Reader Vulnerabilities

Original release date: June 10, 2009
Last revised: --
Source: US-CERT

Systems Affected

* Adobe Reader versions 9.1.1 and earlier, 8.1.5 and earlier, and 7.1.2 and earlier
* Adobe Acrobat (Standard, Professional, and 3D) versions 9.1.1 and earlier, 8.1.5 and earlier, and 7.1.2 and earlier


Adobe has released Security Bulletin APSB09-07, which describes
several buffer overflow vulnerabilities that could allow a remote
attacker to execute arbitrary code.

I. Description

Adobe Security Bulletin APSB09-07 describes several
memory-corruption vulnerabilities that affect Adobe Reader and
Acrobat. Some of these vulnerabilities occur when Adobe Reader and
Acrobat handle files with specially crafted JBIG2 streams. An
attacker could exploit these vulnerabilities by convincing a user
to load a specially crafted Adobe Portable Document Format (PDF)
file. Acrobat integrates with popular web browsers, and visiting a
website is usually sufficient to cause Acrobat to load PDF content.

II. Impact

An attacker may be able to execute arbitrary code.

III. Solution


Adobe has released updates to address this issue. Users are
encouraged to read Adobe Security Bulletin APSB09-07 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:

* Open the Edit menu.
* Select Preferences.
* Choose JavaScript.
* Un-check Enable Acrobat JavaScript.
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 the safer option of
prompting 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. This workaround may also
mitigate future vulnerabilities.

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

* Open Adobe Acrobat Reader.
* Open the Edit menu.
* Choose the Preferences option.
* Choose the Internet section.
* Un-check the Display PDF in browser check box.
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. See
Cyber Security Tip ST04-010.

Additional workarounds are available in Vulnerability Note

IV. References

* Adobe Security Bulletin APSB09-07 -

* Vulnerability Note VU#568153 -


The most recent version of this document can be found at:


Feedback can be directed to US-CERT Technical Staff. Please send
email to <cert@xxxxxxxx> with "TA09-161A Feedback VU#568153" in
the subject.

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Produced 2009 by US-CERT, a government organization.

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Revision History

June 10, 2009: Initial release

Version: GnuPG v1.4.5 (GNU/Linux)