Expert: Attacks, Not Vulnerabilities, Are Keys To IT Defense

In the past year, attackers have shifted from mining software advisories for new vulnerabilities to grabbing code from zero-day disclosures, bugs bounty programs, and targeted attacks, according to a security expert.

Security consultant Daniel Guido said last week in a presentation at the Source Boston conference that although thousands of vulnerability reports are issued every year, only 13 of the vulnerabilities discovered in the past year and 27 of the flaws discovered in the past two years were involved in the most popular exploit kits used to fuel mass attacks.

On the other hand, an increasing number of those kits incorporate exploits copied from advanced targeted attacks aimed at enterprises.

"We can step back and study these things that are coming after us, and we can build more informed defenses that are more effective against those particular threats and that are less costly than not having done this process to begin with," Guido said.

Defenders should pay attention to these emerging exploit kits because systems hardened against those attacks would also be immune to the mass attacks that frequently target specific networks, Guido said.

Rather than focus on the more than 8,000 vulnerabilities found in 2010, according to data from security-services firm Secunia, companies need to focus on the techniques that attackers are using, Guido said.

"The goal is not to create invulnerable software, but to minimize the attack. Somewhere along the line we forgot about that," he said. "You have to realize that these applications have vulnerabilities, no matter how many patches we apply or how many pieces of malware we write signatures for."

Focusing on attacks and not vulnerabilities can help companies prioritize their defensive efforts, says Dino Dai Zovi, a well-known independent security researcher. While 27 vulnerabilities threatened the average company in 2009 and 2010, the other 99.7 percent of vulnerabilities could have been given a lesser priority for patching, he says.

"If you look at it that way, you realize that vulnerabilities just don't matter at all," Dai Zovi says. "There is almost no level of mobilization that we -- vendors, organizations, and everyone involved -- could mount to get all these vulnerabilities off our systems in the span of a few years."

Attackers attempt to economize their efforts by copying successful exploits that can reach many computers, rather than writing such exploits themselves, experts say. For example, Guido found that out of the 15 exploit kits widely used in the underground, 11 crimeware frameworks used Java exploits. Turning off Java in the Internet zone could have prevented any attacks based on those vulnerabilities.

Another key defense mechanism is turning on data-execution protection (DEP), Guido said. The exploit packs Guido studied contain methods of compromising systems using 19 memory-corruption vulnerabilities. By turning on DEP, the exploitation of 14 of those vulnerabilities would have been prevented, he said.

"We now know how effective our particular defenses are," Guido said. "We have hard numbers now about how effective, say, DEP is against attacks."

Defense-in-depth still matters, Guido said, and companies should still have a process to patch their vulnerabilities. But to help prioritize their efforts, companies should first protect against the most likely attacks, he noted.

"How can you protect yourself against [advanced persistent threats], when you can't even protect yourself against being accidentally hacked?" Guido asked.

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