[SURBL-Discuss] Re: RFC: sex site domain SURBL

Jeff Chan jeffc at surbl.org
Tue Jul 20 18:37:16 CEST 2004

On Tuesday, July 20, 2004, 4:55:01 PM, Marc Kool wrote:
> Jeff Chan wrote:

>> The main reason we did this was to defeat the "random
>> subdomain" spammers who generate random subdomains to
>> try to defeat simple URI pattern matching or to key
>> their spams to confirm the recipient addresses.  Examples
>> might be "abc1.xyz.spammerdomain.com" and
>> "abc2.xyz.spammerdomain.com".  Those we want to reduce
>> to just "spammerdomain.com" since the randomized/keyed
>> versions may occur only once and the sc.surbl.org data
>> engine tries to increase the likelyhood of inclusion
>> in the list with an increasing number of reports.
>> It may be useful to read about the sc.surbl.org data:

> Yep, the reasons why this is done are clear but are not flawless.
> There are ISPs myisp.net that give customers a subdomain:
> e.g. myspamsite.myisp.net which can not be included in SURBL.
> I also assume that the percentage of these type of domains is not so big...

Yes, I think they are rare because a legitimate ISP would not
want a major spam site on their domain, even a subdomain, for
damage to their reputation, etc.  Any ISP that would willingly
host a spam site on a subdomain of their own domain I think
we would consider rogue ISPs which I would not feel too bad
about blocking entirely.  But few ISPs seem to put themselves
into this position, which is perhaps why big spammers use so
many custom domains.

I think you're right; I can't really think of many examples of
this actually happening, so our design compromise perhaps
seems reasonable.  :-)

> For the record: my originals proposal would make sex.surbl.org more
> of a squidguard-based list than a surbl-based list.

Right, which is fine.  Please see my next message for some
proposed solutions to this.

> One of the reasons to propose sex.surbl.org was the fact that SURBL list
> lag behind reality.  In July I received 156 spams of which 16 were not
> detected by SA+SOME_SARE_RULES+OWN_RULES+SURBL because the SURBL lists 
> were not updates fast enough (the 16 spams were marked as spam at a later
> time because then SURBL marked them and the SA rating went up).
> This is not meant to criticize anybody, just to put a fact.

> I observed that many spams from new domains 
> - share IP addresses
> - automatically forward you to a known sex site (in the squidguard database)
> and proposed sex.surbl.org

There will always be some lag, but once caught, SURBLs have the
potential to limit the spread of the spams, at least ones with
the same URIs mentioned repeately.

Note that the next version of the sc data engine will cut this
lag quite dramatically, especially for those resolving to
frequently appearing spammer IP blocks.  For more info on the
proposed next version of this data engine, please see:


> However, I see some value for the squidguard adult database to be used by software
> behind spamtraps: if an URI is retrieved and redirects you to a known sex site,
> the URI can be added automatically (= fast) to a SURBL list.

> Marc

I agree RBLs are a convenient and fast way to get data out.
It takes good advantage of the existing DNS infrastructure.

Jeff C.

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