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PUBLIC

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ACROS Security Problem Report #2010-09-08-1
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ASPR #2010-09-08-1: Remote Binary Planting in Apple Safari for Windows
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Document ID:     ASPR #2010-09-08-1-PUB
Vendor:          Apple, Inc. (http://www.apple.com)
Target:          Apple Safari for Windows
Impact:          Remote execution of arbitrary code
Severity:        Very high
Status:          Official patch available, workarounds available
Discovered by:   Simon Raner of ACROS Security

Current version 
   http://www.acrossecurity.com/aspr/ASPR-2010-09-08-1-PUB.txt


#####    TEST YOUR COMPUTER'S EXPOSURE TO BINARY PLANTING NOW!      #####
#####          http://www.binaryplanting.com/test.htm               #####

#####          THE BINARY PLANTING RESEARCH REVEALED                #####
#####              http://blog.acrossecurity.com                    #####


Summary
=======

A "binary planting" [1] vulnerability in Apple Safari for Windows allows 
local or remote (even Internet-based) attackers to deploy and execute 
malicious code on Windows machines in the context of logged-on users. 


Product Coverage
================

- Apple Safari 5.0.1 (7533.17.8) for Windows (at least XP, Vista and 
  Windows 7)
- Apple Safari 4.0.5 (531.22.7) for Windows (at least XP, Vista and 
  Windows 7)

Note:  We only tested the above versions; other versions may also be 
affected. 


Analysis 
========

As a result of an incorrect process launching in Apple Safari for Windows, 
an attacker can cause her malicious EXE [1] to be loaded and executed from 
local drives, remote Windows shares, and even shares located on Internet. 

What a remote attacker has to do is plant a malicious explorer.exe on a 
network share and get the user to open an HTML file from this network 
location with Safari - which should require minimal social engineering. 
Then, when the user tries to open one of his downloaded files in the 
containing folder (e.g., menu: Window -> Downloads -> right-click on a 
file -> Show Containing Folder), the malicious explorer.exe is launched 
instead of the legitimate one.

Alternatively, if the HTML file opens (or redirects to) any "file://" 
location, Safari's attempt to launch Windows Explorer will result in 
launching the malicious explorer.exe.

Since Windows systems by default have the Web Client service running -
which makes remote network shares accessible via WebDAV -, the malicious 
EXE can also be deployed from an Internet-based network share as long as 
the intermediate firewalls allow outbound HTTP traffic to the Internet. 

Microsoft's CWDIllegalInDllSearch protection tool [2] DOES NOT protect 
against this attack, as it only affects the way libraries (DLLs) are 
loaded, whereas this is a case of launching an executable (EXE).

More information on binary planting:

- http://blog.acrossecurity.com
- http://www.binaryplanting.com


Mitigating Factors 
==================

- A firewall blocking outbound WebDAV traffic (in addition to blocking all 
  Windows Networking protocols) could stop an Internet-based attack.

- In case of an Internet-based remote attack, Windows can display a "Open 
  File - Security Warning" dialog to the user as part of the Windows 
  "defense in depth" mechanism. Our experience in penetration tests shows, 
  however, that users are likely to okay such warnings when they appear to 
  be coming from a trusted application (in this case, Safari).


Solution 
========

Apple has issued a security bulletin [3] and published remediated 
versions of Safari for Windows that fix this issue.


Workaround 
==========

- Stopping the Web Client service could stop Internet-based attacks as 
  long as the network firewall stops outbound Microsoft Networking 
  protocols. This would not, however, stop remote LAN-based attacks where 
  the attacker is able to place a malicious DLL on a network share inside 
  the target (e.g., corporate) network.

Other workarounds are commercially available to interested corporate and 
government customers under NDA.


Related Services
================

ACROS is offering professional consulting on this issue to interested 
corporate and government customers. Typical questions we can help you 
answer are:

1) To what extent is your organization affected by this issue?

2) Is it possible to get remote code from the Internet launched inside 
   your network? Can this be demonstrated?

3) Have you adequately applied the remedies to remove the vulnerability?

4) Are there other workarounds that you could implement to fix this issue 
   more efficiently and/or inexpensively?

5) Are your systems or applications vulnerable to other similar issues?


Interested parties are encouraged to ask for more information at 
security@acrossecurity.com.
 

References
==========

[1] Binary Planting Goes "EXE" 
    http://blog.acrossecurity.com/2010/09/binary-planting-goes-exe.html

[2] Microsoft's CWDIllegalInDllSearch protection tool
    http://support.microsoft.com/kb/2264107

[3] About the security content of Safari 5.0.2 and Safari 4.1.2 
    http://support.apple.com/kb/HT4333


Acknowledgments
===============

/


Contact
=======

ACROS d.o.o.
Makedonska ulica 113
SI - 2000 Maribor

e-mail: security@acrossecurity.com
web:    http://www.acrossecurity.com
phone:  +386 2 3000 280
fax:    +386 2 3000 282

ACROS Security PGP Key
   http://www.acrossecurity.com/pgpkey.asc
   [Fingerprint: FE9E 0CFB CE41 36B0 4720 C4F1 38A3 F7DD]

ACROS Security Advisories
   http://www.acrossecurity.com/advisories.htm

ACROS Security Papers
   http://www.acrossecurity.com/papers.htm

ASPR Notification and Publishing Policy
   http://www.acrossecurity.com/asprNotificationAndPublishingPolicy.htm


Disclaimer
==========

The content of this report is purely informational and meant only for the 
purpose of education and protection. ACROS d.o.o. shall in no event be 
liable for any damage whatsoever, direct or implied, arising from use or 
spread of this information. All identifiers (hostnames, IP addresses, 
company names, individual names etc.) used in examples and demonstrations 
are used only for explanatory purposes and have no connection with any 
real host, company or individual. In no event should it be assumed that 
use of these names means specific hosts, companies or individuals are 
vulnerable to any attacks nor does it mean that they consent to being used 
in any vulnerability tests. The use of information in this report is 
entirely at user's risk.


Revision History
================

September 8, 2010: Initial release


Copyright
=========

(c) 2010 ACROS d.o.o. Forwarding and publishing of this document is
permitted providing the content between "[BEGIN-ACROS-REPORT]" and
"[END-ACROS-REPORT]" marks remains unchanged.

=====[END-ACROS-REPORT]=====