Google, hackers have discovered, is very good at finding Web-facing security vulnerabilities. But searching for one vulnerability at a time can be slow -- so it's time to automate.
Attackers are now using botnets and Google "dorks" -- clearly defined search parameters -- to speed the process of finding exploitable flaws on the Internet, according to a new report issued today by researchers at Imperva.
"What the hackers are doing is building an army of zombies to perform automated cyber-reconnaissance," says Noa Bar Yosef, senior security strategist at Imperva. "This makes the Google search much more efficient, and it also makes it harder to detect, because each zombie only issues two to four queries per minute, which is not enough to raise a red flag."
"Search engines can be directed to return results that are focused on specific potential targets by using a specific set of query operators," the Imperva report explains. "For example, the attacker may focus on all potential victims in a specified geographic location. In this case, the query includes a 'location' search operator.
"In another scenario, an attacker may want to target all vulnerabilities in a specific website, and achieves this by issuing different queries containing the 'site' search operator," the report continues. "These particular search queries are commonly referred to as 'Google dorks,' or simply 'dorks.'
"Automating the query and result parsing enables the attacker to issue a large number of queries, examine all the returned results, and get a filtered list of potentially exploitable sites in a very short time and with minimal effort."
In some cases, the Dork might focus on a particular application that is known to be vulnerable, Bar Yosef says. It's possible, for example, that a Google Dork search might be responsible for the recent rash of infections found on websites running the osCommerce application -- researchers at Armorize now report that this infection has hit more than 8 million Web pages.
"With a list of potentially vulnerable resources, the attacker can create, or use a ready-made, script to craft targeted attack vectors that attempt to exploit vulnerabilities in pages retrieved by the search campaign," the Imperva report says. "Attacks include infecting Web applications, compromising corporate data, or stealing sensitive personal information."
There's no easy defense against a botnet and a dork search, Bar Yosef says. "If you're online, you're vulnerable," she says. "Your best bet is to assume that your vulnerabilities will be exploited, and take the next steps to mitigate those attacks."
One step that enterprises can take is simply to Google themselves for vulnerabilities, using dorks or other tools to help locate the search engine-facing flaws they could be presenting to hackers. But even a thorough search might not turn up all of the vulnerabilities in your Web-facing systems, Bar Yosef says.
"One thing we need to do is to call upon Google and the other search engines to help," Bar Yosef says. "The search engines may be able to detect this type of activity on their sites and blacklist those who are doing it, or they may be able to tell users when their computers have been compromised, as they have done already in some cases."
In the near term, however, it's likely that the botnet-based search methods will continue to evolve and proliferate, Bar Yosef says. "Attackers are using botnets now to abuse search engines, just as they used them to distribute spam," she says. "What that says is that hackers could go after smaller companies as well as larger enterprises. Everyone could be a target."
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