MS and Mozilla in row over blame for cross-browser attack.
An exploit which involves browsing to a malicious website using
Internet Explorer
, but then launches an attack via a loophole in
Mozilla Firefox
, is causing controversy over which piece of software is ‘vulnerable’.
The attack, apparently discovered simultaneously by two separate groups of researchers, uses the ‘FirefoxURL’ function, which can allow executable code to run from a remote source. When such a call is made from within
Firefox
security measures detect the action as suspicious and prevent it, but
Explorer
accepts the command and passes it straight to the system, allowing malicious code to be run without restraint. The attack is similar to
a problem found
with the
Windows
version of the
Safari
browser some time ago.
While one of the researchers (whose release on the discovery is
here
) describes the problem as an ‘
Internet Explorer
0day’, vulnerability specialist
Secunia
has issued an alert, labelled ‘Highly Critical’, which puts the blame for the flaw on
Firefox
(see
here
).
Mozilla
has released a statement (
here
) saying that, while it believes the problem is down to
Internet Explorer
passing on dangerous data, it nevertheless plans to issue a fix for the problem. According to a report in
The Register
here
,
Microsoft
has denied that its browser is at fault and has no plans to make changes to the behaviour.
Windows
security expert Jesper Johansson has said that
IE
is dealing appropriately with the data passed to it. Johansson was unable to get the exploit to work – his blog entry on the matter,
here
, includes instructions for disabling the dangerous functionality in
Firefox
. Another sample exploit is online
here
. The problem is thought only to affect
Firefox
version 2.0.2 or later.
Posted on 11 July 2007 by
Virus Bulletin
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