full-disclosure - Re: E-Mail viruses

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Message-ID: <00f001c4035e$73215530$fc5a5cd4@sdfx23432m0z86>
From: docco at zeelandnet.nl (docco)
Subject: Re: E-Mail viruses

I still think teaching users to handle attachments correctly would be by far
easier, as this would be a one_time_lesson, while otherwise you would have
to expect all users to keep all_the_time up to date to the last extension
used.
What would happen if some forget their current (now old) extension is not
valid any more? How would those attachments be handled? Would you have to
allow for a reasonable (??) period of time two different "supersecret"
extensions?

The more I think about it, the scarier it gets ...

(And two more ... make 4 cents)
Regards,
Nacho Pobes

----- Original Message ----- 
From: "MacDougall, Shane" <smacdougall@...nalytics.com>
To: "docco" <docco@...landnet.nl>; <full-disclosure@...ts.netsys.com>
Sent: Saturday, March 06, 2004 10:12 AM
Subject: Re: [Full-Disclosure] Re: E-Mail viruses

Curt's idea could be more effective in a client/server environment that used
extensions that changed periodically (fast enough to thwart virus attacks,
etc). The extension transformations could be length/format. How this updated
extension exchange would be implemented would be another kettle of fish...

Just a thought.
Shane

 -----Original Message-----
From: docco
Sent: Sat Mar 06 00:58:09 2004
To: full-disclosure@...ts.netsys.com
Subject: Re: [Full-Disclosure] Re: E-Mail viruses

 Hi all,

>>"The nice thing about this approach is that it completely
>>eliminates the need for any anti-virus on the mail server
>>since all virus attachments are automatically dropped
>>without the need for scanning [...]"

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,
wow, that IS hard to guess) you should:

- Change your whole statregy. As the extension is been compromised you could
not trust ANY attatchment anymore from that moment on, loosing probably good
and valid attachments.

- Inform all users about the "supersecret" extension been compromised and
ask them to use the new "supersecret" extension.

Then, and I'm playing Devil's Advocate, suppose the new "supersecret"
extension gets again compromised in the time users are getting used to this
new second one, and that you, again, have to inform everybody to change once
more the way they send attachments ...

Well I'm guessing, but I'm almost sure some of your users would just quit
their jobs and go insane.

You Can't Judge a Book By Looking At The Cover
(Willie Dixon)
You Can't Judge a File By Looking At The Extension
(Common Sense)

Just my two cents.
Regards,
Nacho Pobes

PS.- I follow the list for a while with great interest and it's a good
learning experience. Thanx to everybody who participate.

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