n.runs-SA-2009.005 - Apple Safari - Information disclosure

2009-06-2300:00:00

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n.runs AG
http://www.nruns.com/ security(at)nruns.com
n.runs-SA-2009.005 23-Jun-2009

Vendor: Apple Inc., http://www.apple.com
Affected Products: Safari Browser 3.2.3 all platforms
Vulnerability: Information disclosure to Denial of Service
Risk: MEDIUM

Vendor communication:

2009/06/07 Bug found
2009/06/08 Preparing PoC's and problem description for three bug
classes (n.runs-SA-2009.004 - n.runs-SA-2009.006);
writing initial email
2009/06/08 Apple releases Safari 4.0 [1]
2009/06/09 Sending initial email in midnight hour (UTC/GMT +2 hours)
2009/06/09 Bot reply mail delivered; received Follow-Up ID
2009/06/09 Due to a press release n.runs is now aware of new release;
testing three PoC's; two of them seems to be fixed
2009/06/10 Apple replies and outlining "to take any report of a
potential security issue very seriously." Asking for PoC's
2009/06/10 Sending all PoC's with further description and outlining
at the time of writing the initial email, n.runs was aware
of new Safari release. Two PoC's (n.runs-SA-2009.005 and
n.runs-SA-2009.006) are not working with new Safari
release but asking to have a closer look into it.
2009/06/11 Apple response two PoC's are not working on the latest
release, so Apple don't see the need for any further
action. With regards to n.runs-SA-2009.004, Apple
acknowledge the issue still affects Safari 4 and is
looking to fix it.
2009/06/15 n.runs informs Apple to release this advisory
due to time difference
2009/06/23 n.runs releases this advisory

Overview:

Quoting http://www.apple.com/safari/:
"What is Safari ?
It's a browser. It's a platform. It's an open invitation to innovate.
Whether on a Mac, PC, iPhone, or iPod touch, Safari continuously
redefines the browser, providing the most enjoyable way to experience
the Internet."

Description:

Passing the file protocol handler to a certain HTML allows to read local
files.
On Windows it is possible to create an instance of Windows Explorer by
calling an executable file. Other operating systems were not tested.

In detail, the following flaw was determined:

Safari fails to sanitaze the file protocol handler thus leading to an
information disclosure, e.g. local file theft.
Creating dynamically a certain HTML tag and using a valid file path to
an executable may lead to a Denial of Service condition.

Impact

An attacker could trigger the vulnerability by constructing a specially
prepared html file. When a user views this file, local content can be
send to a third party. Additionaly, various ghost instances of Window
Explorer may harm the stability of the users system.

Solution:

Apple has issued an update to correct this vulnerability.
For detailed information about the fixes follow the link in
References [1] section of this document.

Credit:
Bugs found by Alexios Fakos of n.runs AG.

References:
[1] http://support.apple.com/kb/HT3613

This Advisory and Upcoming Advisories:
http://www.nruns.com/security_advisory.php

Unaltered electronic reproduction of this advisory is permitted. For
all other reproduction or publication, in printing or otherwise,
contact [email protected] for permission. Use of the advisory
constitutes acceptance for use in an "as is" condition. All warranties
are excluded. In no event shall n.runs be liable for any damages
whatsoever including direct, indirect, incidental, consequential loss
of business profits or special damages, even if n.runs has been advised
of the possibility of such damages.

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