I was getting hammered with blog comment spam. A large part of the problem is how easy it is to spam blogs. Comments are wide open and Movable Type blogs are one of the most widely used. So making some spamming software to spam an arbitrary Movable Type blog a) wouldn't be that hard to do and b) would be useful on a high number of blogs. That's the disadvantage of using popular software (like Windows, Outlook) -- it becomes a target.

Why comment spam a blog? Seems like a pretty useless thing to do, but Google scores this blog pretty highly. So if someone puts text on my blog in a comment, that text and/or link will be rated higher in Google. The more links that are spammed, the higher the rating for the linked place. Spammers are abusing this feature of Google to improve their rating by spamming blogs.

The latest spamming attack was pretty unique however. First of all, the spams came in waves of a few hundred but only exactly 15 comments per post. The software writer was obviously aware that Google would penalize links on overly flooded pages. Every comment had a different IP address, even on the same post. So either the IP was spoofed (unlikely) or a group of computers were coordinated to spam my blog (equally unlikely, so where does that leave me? hehe). The IP changed so I couldn't ban a single IP from the flood.

Most of the attacks happened on popular older posts, which because of the linking scoring system that Google uses, rank highly. They either link to a high profile blogger like Scoble or Dave Winer or were linked to by other people. So the spammer obviously targetted the more popular pages, which could have been found simply by searching Google for this blog. Google sorts the links in the results by score by default.

So I started deleting these spam comments. They were a nuissance and often offensive. But then I got attacked twice more by a few hundred spam comments and that prompted me to start looking for a more permanent solution. I discovered that a lot of people were closing comments on older posts so they couldn't be spammed.

The downside of closing comments on a post is that people can't come back months later and make a comment -- they are already closed. That's a small downside however, because usually by then the discussion has finished, or is no longer relevant. The best comments are usually the ones that are made in the first few days after a post.

So that's how I'm going to fight this: just close comments on posts as they are spammed. I've been also trying to get an automatic script working to close all posts older than a few weeks but haven't had luck yet getting it to work.