Vulnerability Note VU#660993

Adobe Flash 10.1 ActionScript AVM1 ActionPush vulnerability

Original Release date: 10 Aug 2010 | Last revised: 28 Mar 2012

Overview

Adobe Flash contains a vulnerability in the handling of the ActionScript, AVM1 ActionPush command, which can allow a remote, unauthenticated attacker to execute arbitrary code.

Description

Adobe Flash supports two main types of ActionScript, which is the scripting language for Flash. ActionScript 3.0 is supported by the ActionScript Virtual Machine 2 (AVM2), while previous versions are supported by the ActionScript Virtual Machine 1 (AVM1). Flash 9 and later provide both AVM versions for compatibility with both ActionScript varieties. The AVM1 implementation provided with Flash 10.1 contains a vulnerability in the handling of the ActionPush command, which can result in stack corruption. Previous versions of Flash do not appear to be affected.

Impact

By convincing a user to view a specially crafted HTML document (e.g., a web page or an HTML email message or attachment), PDF file, Microsoft Office document, or any other document that supports embedded SWF content, an attacker may be able to execute arbitrary code.

Solution

Apply an update

This issue is addressed in Adobe Flash Player 10.1.82.76, AIR 2.0.3, and Flash CS3 9.0.280. Please see Adobe Security Bulletin APSB10-16 for more details.

Disable Flash in your web browser

Disable Flash or selectively enable Flash content as described in Securing Your Web Browser.

Disable Flash and 3D & Multimedia support in Adobe Reader 9

Flash and 3D & Multimedia support are implemented as plug-in libraries in Adobe Reader. Disabling Flash in Adobe Reader will only mitigate attacks that use an SWF embedded in a PDF file. Disabling 3D & Multimedia support does not directly address the vulnerability, but it does provide additional mitigation and results not in a crash but in a more user-friendly error message.

To disable Flash and 3D & Multimedia support in Adobe Reader 9 on Microsoft Windows, delete or rename these files:

    "%ProgramFiles%\Adobe\Reader 9.0\Reader\authplay.dll"
    "%ProgramFiles%\Adobe\Reader 9.0\Reader\rt3d.dll"
For Apple Mac OS X, delete or rename these files:
    "/Applications/Adobe Reader 9/Adobe Reader.app/Contents/Frameworks/AuthPlayLib.bundle"
    "/Applications/Adobe Reader 9/Adobe Reader.app/Contents/Frameworks/Adobe3D.framework"
For GNU/Linux, delete or rename these files (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 plug-ins will reduce functionality and will not protect against SWF files 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.

Remove Flash

Adobe has provided a TechNote with utilities for uninstalling the Flash Player plug-in and ActiveX control on Windows and Mac OS X systems. Removing these components can mitigate the web browser attack vector for this vulnerability. Note that this will not remove the instances of Flash Player that are installed with Adobe Reader 9 or other Adobe products.

Disable JavaScript in Adobe Reader and Acrobat

Disabling JavaScript can help mitigate some techniques that use Adobe Reader as an attack vector.

To disable JavaScript in Adobe Reader:
  1. Open Adobe Acrobat Reader.
  2. Open the Edit menu.
  3. Choose the Preferences... option.
  4. Choose the JavaScript section.
  5. Uncheck the Enable Acrobat JavaScript checkbox.
Disabling JavaScript will not resolve the vulnerabilities, it will only disable the vulnerable JavaScript component. When JavaScript is disabled, Adobe Reader and Acrobat prompt to re-enable JavaScript when opening a PDF that contains 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 displaying of PDF documents in the web browser

Preventing PDF documents from opening inside a web browser reduces the attack surface. If this workaround is applied to updated versions of Adobe Reader and Acrobat, it may protect against future vulnerabilities.

To prevent PDF documents from automatically opening in a web browser with Adobe Reader:
  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.
Enable DEP in Microsoft Windows

Consider enabling Data Execution Prevention (DEP) in supported versions of Windows. DEP should not be treated as a complete workaround, but it can mitigate the execution of attacker-supplied code in some cases. Microsoft has published detailed technical information about DEP in Security Research & Defense blog posts "Understanding DEP as a mitigation technology" part 1 and part 2. DEP should be used in conjunction with the application of patches or other mitigations described in this document.

Vendor Information (Learn More)

VendorStatusDate NotifiedDate Updated
AdobeAffected01 Jun 201010 Aug 2010
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base 9.0 AV:N/AC:M/Au:N/C:C/I:C/A:P
Temporal 7.0 E:POC/RL:OF/RC:C
Environmental 7.0 CDP:ND/TD:ND/CR:ND/IR:ND/AR:ND

References

Credit

This vulnerability was reported by Will Dormann of the CERT/CC.

This document was written by Will Dormann.

Other Information

  • CVE IDs: CVE-2010-0209
  • Date Public: 10 Aug 2010
  • Date First Published: 10 Aug 2010
  • Date Last Updated: 28 Mar 2012
  • Severity Metric: 10.02
  • Document Revision: 20

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