New virus first to infect Macromedia Flash

[InfoSec News <isn () c4i org>]

http://news.cnet.com/news/0-1005-200-8410601.html?tag=mn_hd

By Robert Lemos
Staff Writer, CNET News.com 
January 8, 2002, 3:05 p.m. PT 

Antivirus companies warned PC users Tuesday that future Macromedia
Flash movies could carry malicious viruses and worms.

The caution came after an unknown virus writer sent just such an
infectious program to U.K. antivirus company Sophos. Dubbed
SWF/LFM-926, the new program does little but infect Flash files on a
PC when the movie is played.

"It's really a proof of concept, as opposed to something that you
should lie awake at night worrying about," said Graham Cluley, senior
technology consultant for the Abingdon, England-based company. "But
whenever a new vulnerability like this is found, other copycats tend
to create more malicious variants."

The SWF/LFM-926 should mainly be a concern to Web site designers who
use Flash animations to add pizzazz to their sites, Cluley said. Flash
technology, created by digital media company Macromedia, is typically
used on sites to add interactive user interfaces and multimedia
presentations.

Macromedia went even further, calling the vulnerability through which
the virus spread "not that serious."

"Ninety-nine-point-nine percent of the time, people play Flash movies
from the Web in their browser," said Pete Santangeli, vice president
of engineering for Flash at the San Francisco company. "That's
completely safe."

It's only when a Flash file or movie is played on a PC through a
standalone player included with Macromedia's authoring tools for Web
designers that this type of virus can actually infect a PC.

When the infected Flash movie is played, the virus displays the
message "Loading.Flash.Movie..." and drops a 926-byte DOS file onto
the PC. This file--named V.COM--is run by the virus and infects all
other Flash files in the current directory. The SWF/LFM-926 virus'
name is derived from the abbreviation for Shockwave Flash, as
Macromedia Flash used to be known, the displayed message and the size
of the file.

The virus will infect only Windows NT, Windows 2000 and Windows XP
systems, but has not yet been seen circulating the Internet. Moreover,
since the virus doesn't have a way to spread quickly, it's unlikely to
infect a large number of PCs in its current form, said Craig Schmugar,
virus research engineer for security-software maker Network
Associates.

"It won't be a very effective spreading method if they only use
Shockwave Flash," he said, citing NAI tests that confirmed the virus
will not spread when the Macromedia Flash is played in a Web browser.

"It is a double-edged sword," he said. "They have given their
authoring community an ability to create increased functionality. For
the most part, Macromedia has been strict about security; it would
have been difficult for them to see this coming."

The virus is not the first to try to fool those PC users with a
weakness for Flash movies. In December 1999, the ProLin worm spread
through e-mail by posing as a Flash movie, but in reality it was a
simple Windows program file.

SWF/LFM-926 is a pure virus, meaning the program infects files and can
only spread when the compromised file is moved to another system.

Macromedia will release a workaround to disable the file association
between Flash files and the local Flash player within a couple of
days, Macromedia's Santangeli said. In addition, the company plans to
close the hole in the player by the next version.

For the time being, e-mail users will have to add the SWF file format
to their list of attachments of which to be wary.

"Just as we have seen a first Adobe Acrobat file infector and the
first AutoCAD file infector, this is just a new way to get into the
PC," Sophos' Cluley said. "It does show that the virus writers are
always looking for new battlegrounds."



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