Spammers dodge junk filters with Google Translate

Spammers are using Google's good reputation to dodge mail filters deliver their irritable spew to inboxes across the Internet.

The junkster tactic was discovered by Barracuda Labs after examining the messages from a variety of large-volume spam campaigns showing up in the company's honeypots.

The messages contain links that use Google Translate to hide the ultimate destination of the link -- typically a website hawking gray market pharmaceuticals.

Most targets of the spam will ignore it and the link when they receive it because of the obvious intent of its content. But as Barracuda noted in a blog post, "Someone must be clicking on them because these spammers show no signs of giving up."

Ordinarily, spammers choose websites with lower profiles than Google to whitewash the links in their annoying missives. "One of the primary reasons that small weakly defended websites are hacked is to install simple redirect code," Barracuda explained.

That allows the spammer to take advantage of the good reputation of the website to evade spam filters, it continued, while anyone foolish enough to click on the links in a message, will be taken to the hacked website which will redirect them to the website that the spammer is promoting.

However, the Google Translate dodge is a little more complicated. Clicking on the link takes you to Google Translate, but it also instructs the service to go to a website in France and translate a page there that's written in Russian.

Once the Russian page is translated into English and displayed in an iFrame by Google Translate, GT executes code sent to it by the French website, breaks out of the iFrame and sends the victim to the real destination of the link: the pharmaceutical site.

[Also see: Spam fighter, spammer spat becomes massive DDoS attack]

Matters are complicated further by the spammers using URL shorteners to make the links even more difficult to identify by email filters.

"Because of the reputation of Google, the spam with shortened URL links are able to use reputable intermediaries such as bit.ly, y.ahoo.it, and lnkd.in," Barracuda Research Scientist Dave Michmerhuizen explained to CSO. "The use of the Google domain makes it harder for these services to detect abuse."

"A mitigating factor is that the spam we've seen so far has been easy to spot -- pharmacy and porn spam, so even if people see it we hope that they are unlikely to open it," he added.

Google said it will take strong action against any website that violates its webmaster guidelines. "We have algorithms in place designed to detect spam and automatically take action," a representative said. "We take both webspam and email spam very seriously, and we take strong action on it."

Signs that Google was aware of the translate exploit have been spotted by Barracuda. "[I]t appears that Google may be implementing code that defeats framebusting, but our tests are inconclusive," the company said.

"Some links now redirect to google.com, while others still redirect to pharmacy sites," it explained. "We certainly hope this technique is not discovered by malware distributors."

The translate exploit is all part of the endless cat-and-mouse game between spammers and spam fighters, observed Wade Williamson, a senior security analyst with Palo Alto Networks.

"As long as spammers get some return --even though now it may not be as valuable as it was in the past -- I certainly don't see spam going away altogether any time soon," Williamson told CSO in an interview.

While the translate tactic has an interesting twist, spammers are full of interesting twists, added Dave Jevans, chairman and CTO of Marble Security. "Translate is a clever thing," he said. "But they'll find another clever thing next week."

Read more about social engineering in CSOonline's Social Engineering section.