Firespoofing [Firefox 1.0]

[mikx]

__Summary

Using javascript it is possible to spoof the content of security and
download dialogs by partly covering them with a popup window. This can fool
a user to download and automaticly execute a file (if a file extension
association exists) or to grant a script local data access (if codebase
principals are enabled).

__Expected Behavior

Modal dialogs should always be on top and it should not be possible to
obfuscate their appearance.

__Proof-of-Concept

http://www.mikx.de/firespoofing/

The PoC is designed for Firefox 1.0 running in a maximized window.

Part 1 - download dialog spoofing
Shows how to cover a download dialog and fool the user to execute a file
with a standard windows file association (in this case a .ht file). BTW,
remember the latest .ht buffer overflow...

Part 2 - security dialog spoofing
Shows how to cover a security dialog. Make sure codebase principals are
enabled (not default but encouraged by many XUL sites). Creates the file
c:\booom.txt to proof local system access.

__Status

The bug is confirmed but currently unfixed (open for more than 3 months). As
a partial workaround set dom.disable_window_flip to true in about:config.
The vendor failed to respond to multiple status requests which led to this
public disclosure.

2004-09-20 Vendor informed (bugzilla.mozilla.org #260560)
2004-09-20 Vendor confirmed bug
2004-10-20 Status request (open for 1 month - no reply)
2005-01-03 Status request (open for 3 months - no reply)
2005-01-07 Status request (disclosure warning - no reply)
2005-01-11 Public disclosure

__Affected Software

Tested with Firefox 1.0, Mozilla 1.7.5 and Netscape 7.1 on Windows XP SP2.

__Contact Informations

Michael Krax <mikx@mikx.de>
http://www.mikx.de/?p=7

mikx

[Pavel Kankovsky]

On Tue, 11 Jan 2005, mikx wrote:

> The bug is confirmed but currently unfixed (open for more than 3 months). As
> a partial workaround set dom.disable_window_flip to true in about:config.

Setting most of dom.disable_window_open_feature.* to true (and making it
impossible to remove browser "decorations" from browser windows) is a
pretty efficient (even if not 100% bullet-proof) way to thwart this kind
of attack. As well as other GUI spoofing attacks.

--Pavel Kankovsky aka Peak [ Boycott Microsoft--http://www.vcnet.com/bms ]
"Resistance is futile. Open your source code and prepare for assimilation."