According to the researchers, their tool -- an acronym for Block All Drive-By-Download Exploits, which they tested with both Internet Explorer and Firefox -- "successfully blocked all drive-by malware installation attempts from the more than 1,900 malicious websites tested," producing no false positives and consuming minimal system resources. In comparison, "major antivirus software programs caught less than 30% of the more than 7,000 drive-by download attempts from the same websites."
As opposed to malware that circulates via spam email attachments, attackers can infect websites with malicious code, then use them to push malware via drive-by-downloads onto PCs with known or zero-day vulnerabilities, oftentimes infecting them silently. According to Georgia Tech, "approximately 560,000 websites -- and 5.5 million web pages on those sites -- were infected with malware during the fourth quarter of 2009." Visiting any one of those websites or pages could expose someone to drive-by-downloads.
To block such attacks, "Blade monitors and analyzes everything that is downloaded to a user's hard drive to cross-check whether the user authorized the computer to open, run or store the file on the hard drive," said Wenke Lee, a professor in the School of Computer Science in Georgia Tech's College of Computing, who's also part of the Blade development team. "If the answer is no to these questions, Blade stops the program from installing or running and removes it from the hard drive."
"Other research groups have tried to stop drive-by downloads, but they typically build a system that defends against a subset of the threats," said Lee. "We identified the one point that all drive-by downloads have to pass through -- downloading and executing a file on the computer -- and we decided to use that as our chokepoint to prevent the installs."
But the team cautioned that its tool couldn't stop social engineering attacks, or users who didn't set their browsers to require their explicit consent before downloading anything from the Internet. According to the researchers, "Internet users are still the weakest link in the security chain."