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Google, Yahoo, Microsoft, Craigslist... Losing the War Against Spam

added by michael on 8 Aug 2008

It's not just Captcha that has fallen to the barbarian hordes...  virtually every technology that larger service providers have used to defend themselves has been exploited in some fashion.  Huge targets garner a huge amount of attention.

 

Tech World records the struggle: 

By January 2008, Yahoo Mail's CAPTCHA had been cracked. Gmail was ripped open in April. Hotmail's top got popped during the same month. And then things got worse.

 

There are now programs available online (no, we will not tell you where) that automate CAPTCHA attacks. You don't need to have any cracking skills. All you need is a desire to spread spam, make anonymous online attacks against your enemies, propagate malware or, in general, be an online jerk.

 

It's not just free email sites that can be made to suffer, though.

 

John Nagle, founder of SiteTruth, a site that tries to identify bogus businesses and their websites, wrote in late May on Techdirt that while spam on the popular online classified ad service Craigslist "has been a minor nuisance for years ... this year, the spammers started winning and are taking over."

 

Craigslist tried "to stop spamming by checking for duplicate submissions," Nagle explained. "They check for excessive posts from a single IP address. They require users to register with a valid email address. They added a CAPTCHA to stop automated posting tools. And users can flag postings they recognise as spam."

 

According to Nagle, waxing sarcastic, "Several commercial products are now available to overcome those little obstacles to bulk posting. A tool called CL Auto Posting Tool is one such product. It not only posts to Craigslist automatically, it has built-in strategies to overcome each Craigslist anti-spam mechanism."

 

It's not the only one. There are, he added, "other desktop software products [such as] AdBomber and Ad Master. For spammers preferring a service-oriented approach, there's ItsYourPost." The result? "The defenses of Craigslist have been overrun. Some categories on Craigslist have become over 90 percent spam. The personals sections were the first to go, then the services categories, and more recently, the job postings."

 

Of course, you don't have to pay anything. There are now free CAPTCHA crackers available online.

 

Craigslist is fighting back. The organisation is now using phone verification for some ads. Crackers, in return, are working on a way to break Craigslist's phone defences. With combat costs mounting, it's hard to see how Craigslist, which has always been a free service, can continue to survive with its no-visible-means-of-revenue model.

 

It's not, as the Craigslist situation shows, that malicious email is the only problem coming from broken CAPTCHA security. Paul Wood, senior analyst at MessageLabs, a UK-based e-mail security company, says, "MessageLabs have already begun to see examples of spammers exploiting other techniques once they have bypassed the CAPTCHA of Google and Hotmail - for example, using Google Docs to create spam content and including the link in the spam email messages, evading traditional antispam techniques that rely on identifying known spam domains in URLs."

 

Social network users are also vulnerable to attack from CAPTCHA-compromised sites, says Stephan Chenette, manager of security research at Websense Security Labs.

 

"The newer generation doesn't use email to communicate," Chenette explains. "Instead, they use social networks, and they're not too concerned about revealing their personal information on social networks or blogs where they post instead of sending email. What happens is that an attacker creates a public blog of his own or sets up an account; he can then use these to publish malicious links. By exploiting the trust of the people on that community, he uses them to spread botnets and the like."

 

Because social networks offer such an "enormous attack surface" and "their users don't think of themselves as being vulnerable in the same way experienced email or IM users are," they're especially easy to exploit, says Chenette.

 

Another new attack vector is coming from CAPTCHA's collapse: the quick creation of fake websites. According to Chenette, these sites get their content from legitimate websites by copying and pasting to maximise their search engine optimisation and reputation to quickly gain an audience.

 

"Reputation is all the rage for malicious attackers. From a search engine perspective, the content is what matters. Malicious attackers will pull sites' contents and embed it in their site, and that gives them a high search-engine ranking, which gives them a higher reputation," says Chenette. "We've been seeing that quite a lot recently. Of course, search engine poisoning is quite old, but now reputation sites [such as Digg] that use CAPTCHA are being targeted."

 

So what will be the answer?  No one knows.  Expect to encounter more complicated "Human Detection" on websites in the near future: automatic tests that