Fighting email spam and anti-UBE pointers

Archive-name: mail/anti-ube-pointer
Posting-Frequency: 2 times a month
Maintainer: Jari Aalto A T cante net

Announcement: "Bounces, Challenge-response systems, MTA, Bayesian tools (article pointer)"

Availability

FAQ archive is at http://www.faqs.org/faqs/

This message is an excerpt from bigger from Procmail Module
Library project's README.html document titled "Procmail
strategies against spam." available at
http://pm-lib.sourceforge.net/

The key points discussed in the document:

- Auto-replying or bouncing is considered a bad tactic
- MTA rejects can be abused and system administrators should
check their setup at least in regard to viruses.
- Challenge-Response system is based on false assumption that sender's
address can be used for authentication. It cannot and thus any C-R
system will contribute nothing else by amplifying the spam problem.

See picture http://pm-lib.sourceforge.net/pic/cr-system-joe-job.png

What should be done then?

- Bayesian tools are non-intrusive, harm no third parties
(in contrast to C-R), are easy to use and provide a good shelter.
- Battery of bayesian tools give even better shield due to
each program using a slightly different algorithm.

Many clarifying pictures are included:

- How address harvesting works
- How viruses should not be treated (at MTA level)
- Challenge-Response based authentication (overview)
- Challenge-Response system causing "Joe-Job"
- How MTA level UBE prevention works
- Procmail with battery of statistical tools

Table of contents:

1.0 Thoughts about increasing spam annoyance
1.1 Bouncing messages do no good
1.2 Rule based systems are not the solution
1.3 Challenge-Response systems make matters worse
1.3.1 Challenge-Response is not a doorbell but a
gun shooting decoys
1.3.2 Questioning Challenge-Response systems implementations
1.3.3 Summary - What are the effects of Challenge-Response
systems
1.4 Spam appearing in your yard - a story

2.0 A lightweight UBE block system with pure procmail
2.1 Suitable for accounts which ...
2.2 Where to put "pure procmail" UBE checks?
2.3 Using Procmail Module Library to fight spam

3.0 A heavyweight UBE blocking system
3.1 Advice for Debian Exim 4 mail system administrator
3.2 Advice for the normal account
3.3 Configuring Bayesian programs
3.4 A heavyweight spam catch setup using procmail

Some terminology

._UBE_ = Unsolicited Bulk Email
._UCE_ = (subset of UBE) Unsolicited Commercial Email

_Spam_ = Spam describes a particular kind of Usenet posting (and
canned spiced ham), but is now often used to describe many kinds of
inappropriate activities, including some email-related events. It
is technically incorrect to use "spam" to describe email abuse,
although attempting to correct the practice would amount to tilting
at windmills.

_Spam_ = definition by Erik Beckjord. "Some people decide that Spam
is anything you decide you want to ban if you can't handle the
intellectual load on a list." Remember, not to be confused with
real spam, which is unwanted bulk mail.

People are nowadays seeking a cure which will stop
or handle UBE. That can be easily done with procmail (under your
control) and with sendmail (by your sysadm). In order to select the
right strategy against UBE messages, you should read this section
and then decide how you will be using your procmail to deal with it.

Re: Fighting email spam and anti-UBE pointers

On comp.mail.misc, in , " (Jari Aalto+mail.procmail)" wrote:


> Newsgroups: comp.mail.misc,comp.answers,news.answers

Fortunately, almost no one subscribes to any of those
newsgroups, so almost no one will see this spammer's attempt
to convince people to use spam filters that he and his criminal
buddies can easily beat, and to avoid the only type of spam
filters that they _can't_ beat.

Like all petty criminals he's too lazy to do a good job of it.

He should follow my example and post to hundreds of newsgroups
every week with a link to a real anti-spam website contained
in what looks like just a normal query to the newsgroup.

That website gets about 3000 hits a week at this point.

No. I never post that link here. Why bother? No one reads
this group but spammers and trolls, by-and-large.

Want to find it? Just cruise the Usenet and read everyone's
sig.



[Note: I don't read the posts of "Sam" or his numerous
sockpuppets or his 'friends', nor any responses to them.]


Alan


--
URLs of possible interest in my headers.

FAQ: Canonical list of questions Beavis refuses to answer (V1.50) (was Re: Fighting email spa

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Usenet Beavis writes:

> On comp.mail.misc, in , " (Jari Aalto+mail.procmail)" wrote:
>
>
>> Newsgroups: comp.mail.misc,comp.answers,news.answers
>
> Fortunately, almost no one subscribes to any of those
> newsgroups, so almost no one will see this spammer's attempt
> to convince people to use spam filters that he and his criminal
> buddies can easily beat, and to avoid the only type of spam
> filters that they _can't_ beat.

Fortunately, everyone loves reading Usenet Beavis's latest kookfarts, and
everyone will amuse themselves with this recurring spectacle.

Can't beat quality entertainment. Especially when it's free.

> No. I never post that link here. Why bother? No one reads
> this group but spammers and trolls, by-and-large.

And, Beavis, which one of these categories would you place yourself into?


> [Note: it's not my fault that I'm a complete dumbass. I was dropped on my
> head as a child. See http://www.pearlgates.net/nanae/kooks/alanconnor for
> more information]

FAQ: Canonical list of questions Beavis refuses to answer (V1.50)

This is a canonical list of questions that Beavis never answers. This FAQ is
posted on a semi-regular schedule, as circumstances warrant.

For more information on Beavis, see:

http://www.pearlgates.net/nanae/kooks/alanconnor.shtml

Although Beavis has been posting for a long time, he always remains silent
on the subjects enumerated below. His response, if any, usually consists of
replying to the parent post with a loud proclamation that his Usenet-reading
software runs a magical filter that automatically identifies anyone who's
making fun of him, and hides those offensive posts. For more information
see question #9 below.

============================================================ ================

1) If your Challenge-Response spam filter works so well, why are you munging
your address, when posting to Usenet?

2) If spammers avoid forging real E-mail addresses on spam, then where do
all these bounces everyone reports getting (for spam with their return
address was forged onto) come from?

3) If your Challenge-Response filter is so great, why do you still munge
when posting to Usenet?

4) Do you still believe that rsh is the best solution for remote access?
(http://tinyurl.com/5qqb6)

5) What is your evidence that everyone who disagrees with you, and thinks
that you're a moron, is a spammer?

6) How many different individuals do you believe really post to
comp.mail.misc? What is the evidence for your paranoid belief that everyone,
except you, who posts here is some unknown arch-nemesis of yours?

7) How many times, or how often, do you believe is necessary to announce
that you do not read someone's posts? What is your reason for making these
regularly-scheduled proclamations? Who do you believe is so interested in
keeping track of your Usenet-reading habits?

8) When was the last time you saw Bigfoot (http://tinyurl.com/23r3f)?

9) If your C-R system employs a spam filter so that it won't challenge spam,
then why does any of the mail that passes the filter, and is thusly presumed
not to be spam, need to be challenged?

10) You claim that the software you use to read Usenet magically identifies
any post that makes fun of you. In http://tinyurl.com/3swes you explain
that "What I get in my newsreader is a mock post with fake headers and no
body, except for the first parts of the Subject and From headers."

Since your headers indicate that you use slrn and, as far as anyone knows,
the stock slrn doesn't work that way, is this interesting patch to slrn
available for download anywhere?

11) You regularly post alleged logs of your procmail recipe autodeleting a
bunch of irrelevant mail that you've received. Why, and who exactly do you
believe is interested in your mail logs?

12) How exactly do you "enforce" an "order" to stay out of your mailbox,
supposedly (http://tinyurl.com/cs8jt)? Since you issue this "order" about
every week, or so, apparently nobody wants to follow it. What are you going
to do about it?

13) What's with your fascination with shit? (also http://tinyurl.com/cs8jt)?

14) You complain about some arch-nemesis of yours always posting forged
messages in your name. Can you come up with even a single URL, as an example
of what you're talking about?

15) You always complain about some mythical spammers that pretend to be
spamfighters (http://tinyurl.com/br4td). Who exactly are those people, and
can you post a copy of a spam that you supposedly received from them, that
proves that they're really spammers, and not spamfighters?


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