Another Windows zero-day exploit seen in wild

Trojans sneaking in through animated cursor flaw.

A vulnerability has been discovered in the handling of .ani files, used for animated cursors on web pages and in HTML emails, and has been spotted as a proof-of-concept exploit on malware writers’ discussion boards and in use for attacks.

The exploit involves maliciously crafted .ani files, implanted on web pages or spammed via email, and can be used to silently install trojans on victim machines. After an initial blog posting from

McAfee

(

here

), exploitation of the flaw has been reported by numerous sources and

Microsoft

has issued an initial security advisory. Users of most current versions of

Windows

, including

Windows Vista

, are thought to be affected, although the exploit may not work on

Windows XP

without Service Pack 2, and the

Firefox 2

and

Internet Explorer 7

browsers are also thought to be protected from the flaw.

Users are advised to allow only plain-text email, although this may not protect users of the popular

Outlook Express

, or the

Windows Live Mail

program included with

Vista

. Administrators may want to consider blocking .ani files at the gateway.

Microsoft

‘s advisory is

here

, while an update to

McAfee

‘s blog posting is

here

and some analysis of an exploit from

Trend Micro

is

here

. An alert from the

SANS Internet Storm Centre

can be found

here

, and another from

Secunia

, labelled ‘extremely critical’, is

here

.

Posted on 30 March 2007 by

Virus Bulletin