[Esa-l] Re: Idea: Multiple extension detector

[John D. Hardin]

On Sun, 11 Jun 2000, Brett Glass wrote:

> >Not so new. All of the .VBS worms were written that way too.
> 
> That's where they got the idea.
> 
> >Interesting idea. I don't think the current version could do it too
> >well, but there's a simple way to put that into your poisoned-files
> >list, assuming you don't want to poison *all* .EXE attachments:
> >
> >   *.[a-z0-9]+.exe
> 
> Doesn't one need to "escape" the dots? (One would in a Perl regular
> expression, but I haven't checked to see whether your pattern language
> is different.)

The syntax of the poisoned-files list is a hybrid of standard regular
expressions and standard file globbing - I wanted it to look more like
extended file globbing than regular expressions, and entries get
interpreted a little before the comparison. Periods may be bare, they
will be escaped for the filename comparison RE; * and ? will be
converted to .* and .? for the RE.

After a bit of thought, a better version of the above is:

   *.[a-z0-9]+.[a-z0-9]+

Since the poisoning is only done on executable extensions, this will
catch (for example) "fnord.txt.com" (assuming you don't already poison
*.com).

--
 John Hardin KA7OHZ   ICQ#15735746   http://www.wolfenet.com/~jhardin/
 jhardin at wolfenet.com      pgpk -a finger://gonzo.wolfenet.com/jhardin
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