Daily Archives: 2006-02-12

EarthLink has just 31 challenge-response CAPTCHAs

EarthLink, the US ISP, provides its users with a number of spam blocking and filtering systems. One of these systems, deployed since 2003 or so, is called “Suspect Email Blocking” and is one of those tedious and ineffective “Challenge-Response” systems. They might have made sense once, but now they just send out their challenges to the third parties whose identity has been stolen by the spammers.

Since the spammers have been stealing my identity a LOT recently — and since Earthlink is failing to detect their emails as spam — I have received several hundred of these Challenge-Response emails 🙁 Effectively, EarthLink customers are dumping their spam filtering costs onto me.

Well I’m now mad as hell and not going to take it any more. So I’ve been responding to these challenges, and whenever possible I’ve been sending along a message that indicates the practical effect of the system. Of course this will mean that the spam will be delivered (and the forged email address will be whitelisted in future) which is hardly what is desired! Since this should be quite noticeable, if everyone was to spend a few minutes each day responding to the challenges then Challenge-Response systems would die out overnight! So please join in!!

Howver, responding is rather tedious (the idea, after all, is that the spammers won’t be able to afford to do it — though in practice they would be able to keep sending their more profitable spam by using labour from the Third World). To avoid this tedium I’ve been working on the automation of my responses. However, the EarthLink web page on which you respond contains a visual CAPTCHA — specifically so as to prevent automatic responses to the challenges. Nevertheless, I got a lot slicker at answering the questions when I wrote some Perl and put up a little Tk widget to collect the answer to the CAPTCHAs.

TK widget for EarthLink CAPTCHAs

The idea was to move on to some fancy image processing since there’s been a lot of success at this (see here and here for starters)… However, that won’t be necessary. It turns out, nearly 300 challenges later, that EarthLink only have 31 CAPTCHAs in total… although since some turn up a great deal more more rarely than others, it may be that there’s a few more to be collected!

01 EarthLink CAPTCHA 01 02 EarthLink CAPTCHA 02 03 EarthLink CAPTCHA 03
04 EarthLink CAPTCHA 04 05 EarthLink CAPTCHA 05 06 EarthLink CAPTCHA 06
07 EarthLink CAPTCHA 07 08 EarthLink CAPTCHA 08 09 EarthLink CAPTCHA 09
10 EarthLink CAPTCHA 10 11 EarthLink CAPTCHA 11 12 EarthLink CAPTCHA 12
13 EarthLink CAPTCHA 13 14 EarthLink CAPTCHA 14 15 EarthLink CAPTCHA 15
16 EarthLink CAPTCHA 16 17 EarthLink CAPTCHA 17 18 EarthLink CAPTCHA 18
19 EarthLink CAPTCHA 19 20 EarthLink CAPTCHA 20 21 EarthLink CAPTCHA 21
22 EarthLink CAPTCHA 22 23 EarthLink CAPTCHA 23 24 EarthLink CAPTCHA 24
25 EarthLink CAPTCHA 25 26 EarthLink CAPTCHA 26 27 EarthLink CAPTCHA 27
28 EarthLink CAPTCHA 28 29 EarthLink CAPTCHA 29 30 EarthLink CAPTCHA 30
31 EarthLink CAPTCHA 31

For rather more detail, and the current totals for each CAPTCHA (some have turned up nearly 30 times, some just once) please see the detailed account which I’ve placed on my own webspace.

By the way: If you’re an EarthLink user reading this — then please turn OFF “Suspect Email Blocking”! You’re just annoying everyone else 🙁