Protecting Your Small Domain from Spam Hijacking?

Black Cardinal asks: "I have a small domain which I mostly use to post family photos and some software. I also use it to manage a few e-mail addresses that my wife and I use. A spammer recently hijacked my domain name, using it to construct fake return addresses for sending spam (without actually cracking my host account), and caused a flood of undeliverable mail messages to be sent to my domain hosting service, which promptly suspended my account. At the moment it looks like I may never be able to have any @gelhaus.net e-mail again. What can I and my domain hosting service do now to protect their incoming mail servers and my account from this kind of attack, and how can I protect my small domain from this kind of hijacking and allow me to keep it running?"

"My domain hosting service, CubeSoft, has been a good host for my domain for the past three years, and they have been very helpful in re-enabling most of my account, but at the moment they don't want to re-enable my e-mail because of the flood of returned spam coming in (30,000 messages per day). Since the return addresses are all invalid (e.g. 'nonexistent_address@gelhaus.net'), I would think it would be simple to filter out all messages that aren't specific ones I've set up (e.g. 'valid_address@gelhaus.net'). I can't believe my domain is the first to have experienced this problem. It would be a tragedy to have to just shut down my domain because of this. CubeSoft says there isn't any way to prevent it because there is nothing that stops a spammer from using a fake return e-mail address. What have others with small domains done to protect themselves?"

Comments

Use SPF to protect against "Joe Jobs"

[Karl J. Smith]

If everyone uses SPF, it will cut down on spam and joe-jobs.

See http://spf.pobox.com You can publish your DNS now, indicating which legitimate IPs are in use for mail from your domain.

An Idea

[ewhenn]

My host is set up so that all emails recieved that have no account (invalid email address) are forwarded to an account with a quota of 1K. Of course the quota is full, so it is an instant bounce. Problem solved. Hope this may help you.

Push the emails back toward the spammer

[Zocalo]

A former colleague of mine had one of her domains *seriously* Joe Jobbed like this a short while ago - thousands of bounces a day. Since the domain wasn't actually used for much she contacted the people that were using it, asking them to use an alternate domain as the obvious stop gap. Her next step was novel to say the least...

A brief investigation of a few of the bounces revealed that the spammer was using a variety of email addresses and domains in the message as their contact point. Many of the domains shared the same mail server, which was obviously a co-lo box, so she simply pointed all of the MX records for her domain towards the spammers primary email server. Unfortunately it wasn't misconfigured to actually accept the bounces, but each bounce was tying up resources and bandwidth belonging to the spammer. When she reset the MX records back a month or so later it was all over.

This is only applicable if you have your own domain like in this instance of course, I doubt an ISP would even consider this course of action with one of their subdomains as it's a dubious course of action to say the least. You also lose all use of your domain while the MX records as repointed, so you better be *damn* sure nothing sensitive is going to be received in legit email because the spammer could, if they wanted, accept and read your email.

Interesting and apparently effective strategy though.