Phishers Enlist Google 'Dorks'

A researcher at MarkMonitor has discovered that 75 percent of phishing sites are built around Google search terms traded and shared in underground forums.

Phishers use these so-called “Google dorks,” or search terms, as a simple way to search for and locate vulnerable Websites to hack -- mainly those based on PHP -- that they then can use to host their phishing attacks. John LaCour, CISSP and director of anti-phishing for MarkMonitor, says he found the trend while canvassing some hacker forums and sampling a group of phishing sites.

"These are search terms that are actively traded by hackers. They have done the work to find the magic strings to find the vulnerable Websites. And they leverage those to install phishing" exploits, LaCour says: He sampled one fourth of all the phishes MarkMonitor had logged, and 75 percent of them had been created by using some 750 Google dorks and the related PHP vulnerabilities to gain access to the victim servers.

LaCour has compiled a spreadsheet full of popular Google dorks. With the dork inurl:index1.php?go=*.php, for instance, the phisher would enter that string into the search engine. "The search results would return a list of potentially vulnerable sites. The attacker then selects one of the sites and exploits the PHP application by referencing their own remote PHP file for inclusion," LaCour says.

He says the bad guys come up with these search terms both by trolling legitimate security research forums as well as sites that publish exploit information, such as Milw0rm.

The process of searching for vulnerable sites isn’t necessarily manual. Some phishers use pre-programmed "search bots" that do the dirty work of Googling for vulnerabilities, he says. "[Hackers] also create search bots that sit in the RFC channel and wait for commands. Hackers log in themselves, type a message, and instruct the bot to send queries to Google, Yahoo, and AOL Search. They use IRC and bots to aggregate these results."

Researcher and phishing expert Nitesh Dhanjani, who with researcher Billy Rios recently infiltrated the phisher universe and found most are not as sophisticated as you’d think, says phishers' use of Google dorks jibes with the low-tech level of expertise he and Rios saw in their research. (See Researchers Expose 'Stupid Phisher Tricks'.)

"This drives home the point that the average phisher isn't the Einsteinian ninja hacker that the media makes them out to be -- they don’t employ sophisticated techniques, but rely on easy to exploit issues," Dhanjani says. "This particular instance illustrates how phishers are after the low-hanging fruit -- high rewards, yet very little effort required."

MarkMonitor’s LaCour says he has shared his list of Google dorks with Google itself, which has already taken several steps to prevent or limit automated queries. “But nothing can be done to stop [phishers and bad guys] from using them manually.”

Much of the problem, he says, is that there’s a nearly endless stream of vulnerable, PHP-based Websites that phishers can use. "They are using these sites to host stolen information, and they tend to be smaller sites, like the local PTA chapter or the local Frisbee club," he says. "These smaller sites are not as likely to have updated patches for their applications."

As PHP has increasingly become a popular Web platform, its number of vulnerabilities has risen as well. LaCour says there are now over 1,800 known PHP application vulnerabilities, the most popular being remote file inclusion (RFI) bugs. "RFI is easy to exploit," he says.

But Google dorks aren’t just for phishing. "They are using the same techniques for defacing sites and putting up blogging pages for a hacker group," for instance, LaCour says. They also are used to hack Websites and databases for more vulnerable small sites. "It’s a basic [hacking] technique for any purpose."

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