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Fighting the Hydra -- A Spam Warrior's Tale
Selanit writes "Salon has an interesting article about the battle against spam from the viewpoint of Suresh Ramasubramanian, a sysadmin working in Hong Kong. His most interesting complaint concerns the fragmentation of anti-spam forces: not only does he have to deal with spammers, but also with anti-spammers who assume because his company is Chinese that he isn't doing anything about spam. Hmm ... decentralized opponents striking from the shadows against quarreling allies. Does this sound familiar to anyone else?"
No matter what he does, he can't please everyone. According to Tiffiany Mork, senior abuse engineer at Allegiance Internet, a very thick skin is a requirement for an abuse-desk worker. Her typical day includes verbal harassment, screaming, threats, and "all manner of nasty things."
Like that is different from working in any other kind of helpdesk!
This whole spammers versus spamblockers has proven to be a destructive arms race.
Many legitimate machines and users - even whole ISPs - unfairly end up on blacklists, while the spammers just find another way through.
The spamblocker tools and their heuristics get smarter, but don't forget that spammers keep up with these tools and constantly find new ways around them.
I was using Razor and SpamAssassin for months. Formidable combination - networked blocklists plus pattern matching. Gave me a bit of peace. Very few false negatives. But in the last month, I've seen a whole new generation of spam coming through that the filters don't even touch.
Peace has finally come from a package called Active Spam Killer, a package which works from a white list, and provides a convenient way for new correspondents to get themselves onto the whitelist.
There are other whitelist-based packages, such as TMDA, but ASK is simple and painless to set up.
Result?
Spams to my mailbox have gone from 40 a day to zero.
-- In the beginning was the WORD, and the WORD was UNSIGNED, and the main(){} was without form and void...
If 50% of all mail in the US is spam, then the other 50% must be the bounces for all that undeliverable mail!
I run a mail gateway for a medium sized company, and although not on the scale of a large ISP, I see many of the same problems. Dealing with spam on a gateway level is quite different from dealing with a single personal mailbox. And spam flooding has gotten much worse in the last few months. Getting over a 1000 messages in under a minute can really start to tax your infrastructure. Actually from my own observations, I'd say that at least 75% of all mail is spam, and 80% of that is undeliverable.
Of course one of the big problems as Ramasubramanian points out is that spammers are getting very sophisticated at impersonating other entities. This results in a large number of bounces being directed back to the wrong guy. So not only are you getting spammed, but you are also indirectly spamming the poor guy who is being impersonated with your flood of bounces. And the bounces also cause other problems because it tends to fill up your outbound mail spools, as well as making the required postmaster account near useless sometimes.
One thing I've learned is that a mail administrator must be very careful about constructing blacklists and filters. I use sendmail and make heavy use of it's milter programatic filter interface. It's amazing how being able to analyze the mail at the protocol level (such as the HELO command) helps identify impersonated mail that can't just be done by only looking at mail headers or the message body. It is also possible to help correlate large volumes of nearly identical inbound mail from a large number of different servers, as well as correlate them with large number of undeliverable outbounds. I'm also very careful to check whois an other registrar databases before adding blacklist entries, to help prevent blacklisting the wrong guy. But I do admit that for a few of the most audacious flood attacks, I actually have to resort to iptables firewall blocks to stop it even before sendmail sees it. I really dislike having to disobey the SMTP standards, but spam floods are IMHO just as destructive as worms and viruses!
The thing I fear most as a mail administrator is not the inbound spam, but that some spammer may start impersonating my company! We'd start getting placed on blacklists and blocked, plus we'd start getting flooded with all those bounce messages (probably an order of magnitude more than direct spam). How can one possibly protect against that?
Shuresh is also a regular poster in the newsgroup news.admin.net-abuse.email, a discussion forum about e-mail abuse.
Check his postings from the Google Groups archive.