Rex,
Good point and generally this is true, but we are talking viruses.

From Trend's (www.antivirus.com) virus encyclopedia on the VBS_LOVELETTER and variants :
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VBS_LOVELETTER has generated many variants (copycats) and the following descriptions (below) show how they differ from the original...<things cut out here for brevity>

However, due to Explorer default setting a file named: nameoffile.jpg.vbs, will appear in Windows as nameoffile.jpg only, with the .vbs hidden from view. If you click on this attachment Windows will execute the file instead of opening the default .jpg viewer.

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Chances are the list in question will not let this in because it's extension is .vbs not jpg. But because Windows Explore saws jpg, doesn't necessarily make it so. I still maintain the best options for virus protection other than public flogging for perpetrators are user education and multi-layer Anti Virus software.


Doug

Doug Wheeler
Sr. Technical Analyst - Information Resources
Neenah Technical Center
Georgia-Pacific Corporation
email : mailto:[log in to unmask]
voice : 920.729.8178 fax : 920.729.8164




-----Original Message-----
From: rex [mailto:[log in to unmask]]
Sent: Monday, August 05, 2002 1:22 PM
To: [log in to unmask]
Subject: Re: Limiting types of images - another try


On Mon, 05 Aug 2002 at 02:09:57PM -0400, Wheeler, Doug (NTC) wrote:
> It seems to me that to rely on limiting image type to jpg/jpeg with a
> size limit (or similar approaches) as a virus protection is extremely
> risky.
>
> Yes, you will avoid some of the viruses that fall within those
> parameters, but what about the other methods that these creeps use?
> (what happens if a virus is 600 lines, with a false extension of
> jpg?)

Files with a .jpg extension do not get executed and thus pose no
viral threat regardless of the actual content.

Regards,

-rex