Spamhaus comments on subscription attack

Steve Linford, CEO of Spamhaus commented on my blog post about the current listings. I’m promoting it here as there is valuable information in it.

Excellent well summarized article Laura 🙂

No we’ve not changed SBL policy to require COI. It’s something we very strongly advise but we can not make a requirement. We’ll have to consider it if list-bombing of this magnitude can not be kept in check by list managers.

This incident involved a large number of government addresses belonging to various countries being subscribed to very large numbers of lists in a very short space of time by scripts run by the attacker(s). Most of the lists hit by the attack used COI and therefore only sent confirmation requests and did not subscribe any addresses. The attack undoubtably also hit lists which used Captcha in addition to COI and thus did not even proceed to COI (those list admins deserve some sort of community ‘hi 5’ award, since one can imagine how hard it is to convince one’s management to implement COI let alone put Captcha in front of it).

The issue is the badly-run ‘open’ lists which happily subscribed every address without any consent verification and which now continue as participants in the list-bombing of government addresses. These we are trying to address with SBL listings to prompt resolution by the Senders. As you noticed, most of these particular incident listings are for IPs ending “.0/32” which does not cause any mail issue to the Sender and is deliberately used where we have a good relationship with the Sender and know they will act quickly on the alert.

Steve Linford
Chief Executive
The Spamhaus Project

Efforts are ongoing to help ESPs clean up. Multiple commenters have been sharing data in the comments. If you have data you’d like to share with others, but don’t want to share it publicly please contact me directly.


  1. Moliverability says

    This is a targeted attacked for sure! It’s not hard to guess email addresses of corporate entities/governments once you know the domain and syntax.

  2. Chris says

    This could be true if it was just one or two corporate/governments involved (and their employee’s names, not just syntax), but it was a lot more than that. This strikes me more as a test or experiment using a number of mailing lists.

    I can’t tell you how many times people have told me that they were targeted by something, but our trap array shows it to be global and pretty indiscriminate.

    Targetted, perhaps, but likely only weakly.

  3. Two Blogs on Fallout from Two DDoS Attacks » MainSleaze says

    […] CEO Steve Linford discussed the attack, why Spamhaus listed the ESPs, and what they hoped to accomplish on Steve and Laura Atkins’ Word to the Wise blog, a popular bulk email industry forum. In his […]


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