Like most of you know spam is a big problem on the Internet. There are various forms of spam and various techniques to stop spam. A lot of websites and blogs with comment and user registration forms use so-called CAPTCHAs to eliminate most spam.
CAPTCHAs are simple tests to determine whether the user is a human or an automated spam bot. Computers have a really hard time solving these CAPTCHAs and now some clever spammers have found that they can use this technique to their advantage.
Last week Neil Cook from anti-spam firm Cloudmark said that a new trend in the spam world are e-mails with distorted text images in PDF files.
He added: “We’ve been seeing a lot of PDF stock spams for the last 10 days or so, and there was another spike last night. Images are particularly easy for humans to pick up, but particularly hard for computers.
“These ones are distorted too – it’s the same technique that websites use to keep spammers off by making visitors type in distorted text during registration, and now the spammers are using it on us.”
I get lots of spam mails (hundreds a day) and one of the things I’m seeing a lot lately are image-based spam mails like this one for all kinds of pills and also for software like AutoCAD:
The most anything thing about it is that my spam filter doesn’t catch these mails yet