hi..

not having used razor, nor have i looked at the open source for the client.
however, it is my understanding that the client maintains a list of some of
the hash emails that have been identified as spam as a method of reducing
the amount of time/traffic that has to go back to the database. i was also
under the impression that the client had/has some ability to "detect" new
msgs that "might" be spam, even though there may not be a direct "match" to
the spam hashed emails that have already been identified....

but i may be wrong!

-bruce


-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of John
Andersen
Sent: Friday, June 18, 2004 10:34 AM
To: [EMAIL PROTECTED]
Subject: Re: [Razor-users] Detection rates


On Friday 18 June 2004 02:08, Christopher Sharp wrote:
> On Thu, 17 Jun 2004 21:40:36 -0800, John Andersen <[EMAIL PROTECTED]>
wrote:
> >On Thursday 17 June 2004 03:32, Christopher Sharp wrote:
> >>   Figures to date indicate it's NOT a drop in detection rates, but
> >> instead has all the hallmarks of someone having produced a spam package
> >> that actually manages to avoid all SpamNet/Razor algorithms.
> >
> >Razor does not have detection "algorithms" as such but relies on matching
> >spam previously reported to razor by someone prior to your getting it.
> >So if those reporting spam are less active, or if razor has network
issues
> >then spam gets thru.
>
> OK, I'll bite...
>
> To quote the Razor readme:
>       "Detection is done with statistical and randomized signatures that
> efficiently spot mutating spam content."
>
> Razor as a database naturally does not contain any detection algorithms.
> The clients, namely razor-agents, do this.  The database simply stores the
> hashed signatures for determined spam.  Naturally it's more complicated
> than that once you add in TeS, revocations etc.
>
> Ultimately anything contributing signatures to the Razor database must
> apply sufficiently similar algorithms for the database to be of any value
> to the client.

Razor's mode of operation is to have hashes of known spam submitted
to a database.  When your client gets an email, it hashes that email
and queries the databse in a process not unlike a DNS query, except
it uses the hash rather than a domain name.

If the hash is found in the DB, then your client knows its spam.

The client's can't tell its spam on their own, they need the database.
The client's only "smarts" is in the hashing of the message body
and to a lesser extend the hashing of any url's found in the body.

So, getting back to the original posters question, spam need only be
NEW (not yet reported to the Razor db) and it will get thru.

It is not correct to think of spam that gets thru the razor check as
having been designed to evade razor, or to think someone having
"produced a spam package that actually manages to avoid all
 SpamNet/Razor algorithms".

The postulated algorithms do not exist in that sense.  The algorithms
do not "detect" spam.
The only algorithms that exist (if you can call them that) are those
that HASH the spam body and submit it for a razor check.

Once submitted to the database (enough times) anything, ANYTHING
AT ALL will be henseforth considdered as spam.

Therefore it is not necessary to postulate a method to avoid razor's
algorithms, it is merely necessary to assume (in order of probability):
   A flood of   New spam not previously seen
   Slowness or technical problems with the razor database
   Spam reporting to razor falling off (people on vacations , etc)

Further you stated (or were you still quoting?)
  "> Razor as a database naturally does not contain any detection
algorithms.
   > The clients, namely razor-agents, do this.  "

No they don't.  They simply contain hashing algoithms.  Client's do not
detect spam.  They hash all email and submit each hash to the razor
database to ask if it has any record of that hash.

--
_____________________________________
John Andersen



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