full-disclosure - Re: E-Mail viruses

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From: purdy at tecman.com (Curt Purdy)
Subject: Re: E-Mail viruses

docco wrote:
> What Curt Purdy is saying looks to me like a
> great_pain_in_the_ass_solution.
> In case the "supersecret" extension would get leaked or
> compromised, which I
> beleive would be absolutely not hard to achieve (by means of social
> engineering, sniffing or just brute force - combinations of
> three letters,
<snip>

Jeese, it's amazing how a thread can get so twisted overnight.  My original
point was that is was never necessary to hide the proprietary extension and
it would never need to change.  The purpose of blocking everything but this
extension, in our case .dps (see, I'm not scared) is to squash 99.999%
(experience has been 100% so far) of all possible infected attachments
before it ever gets to our email AV server.  Of course that percentage may
now drop if some "security expert" on this list decides to rename netsky and
send it to us.  However that would be a waist of time unless it was a 0-day,
and I doubt anyone would want to waist that on us.

In addition, it is much easier to train users to change the extension than
to "not open attachments" because they are self-motivated to do the former
if they ever want another attachment.  If you try to educate users to do the
latter, you are just setting yourself up to continually battle the social
engineering used by virus coders.

While I'm on the subject, just this morning on a nationally syndicated show,
I heard a piece on the current "virus war" and was amazed when I heard it
end with "a security expert" say "only open attachments from someone you
know".  We disabled notifications on our AV server months ago.

Curt Purdy CISSP, GSEC, MCSE+I, CNE, CCDA
Information Security Engineer
DP Solutions

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If you spend more on coffee than on IT security, you will be hacked.
What's more, you deserve to be hacked.
-- White House cybersecurity adviser Richard Clarke