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Don’t spam filter your role accounts

A variety of “amazon.com order confirmations” showed up in my inbox this morning. They were quite well done, looking pretty close to real Amazon branding, so quite a few people will click on them. And they funnel people who do click to websites that contain hostile flash apps that’ll compromise their machines (and steal their private data, login and banking credentials then add them to botnets to attack other sites and so on).

Not good. Just the sort of urgent, high-risk issue that ISP abuse desks really want to hear about. I sent email about it to the ISPs involved, including a copy of the original email. One of them went to iWeb, a big (tens of thousands of servers) hosting company.

This was the response:

<abuse@noc.privatedns.com>: host mott.privatedns.com[174.142.252.34] said: 554 rejected due to spam content (in reply to end of DATA command)

That’s iWeb’s main abuse address for their address space, as registered with ARIN. They even have a comment in their network registration that says “Please use abuse@noc.privatedns.com for abuse issues”.

For email related abuse (spam, malware email, botnets, phishing, viruses, …) almost all valid, actionable abuse reports will include a copy of the email involved. And that’s exactly the sort of content that content-based spam filters do their best to block. That means that putting content-based spam filters on your abuse or security role addresses will prevent you seeing most reports about abusive traffic coming from your network.

There are some companies that have an intentional policy of rejecting most spam reports sent to them so that their abuse metrics look better, and they don’t have to pay for abuse desk staff to handle the high volumes of abuse reports their customers provoke. “Mistakenly” putting spam filters on their abuse alias is one way of doing that – others include using non-standard abuse aliases, demanding reports come in only via web forms, requiring abuse reports be sent in non-human-writable formats while discarding all others, and many more. If you don’t want to behave responsibly it’s easy enough to dodge those reports.

Legitimate companies really want to know about abusive traffic sooner rather than later, so they can shut it down and mitigate the damage as quickly as possible. Email systems are complex, though, and it’s quite easy for an upgrade to spam filtering at a companies main mailserver to mistakenly by applied to abuse@ and security@ aliases – especially when spam filtering or email services are outsourced. And if you’re a company that uses dozens of domains it’s easy to lose track of where mail to abuse@ some of those domains ends up.

If you’re responsible for email, abuse or security at your organization it’s worth occasionally checking that your role accounts actually work. Find yourself a fairly obvious bit of spam, then forward it to your abuse@ role address (with a sentence or two telling your abuse desk that you’re just testing, and can they reply to your mail so you know they received it).

Real spam sent directly to abuse@ role addresses can be a severe problem, but content-based filtering is not the way to deal with it. One approach that we suggest to our Abacus users is to prioritize reports that mention a URL or an IP address on your network, so that legitimate, actionable reports will “bubble up” above any spam.

3 comments

  1. John L says

    You can also use well-run DNSBLs like the Spamhaus ones on role accounts with little risk of losing reports. Those BLs list only hosts that send 100% spam, which would not include anything from a real person.

  2. Matthew E says

    A better title would be, “Don’t use CONTENT-BASED FILTERS to spam filter your role account.”

    DNSBLs, and other verified sender reputation-based systems are appropriate.

    And I add customer email addresses to the list of things that, if mentioned, bump incoming role email priority.

  3. Kelly Molloy says

    I’m late, but also: don’t include role accounts in spamtraps. It’s bad.

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