Original URL: http://www.theregister.co.uk/2009/04/24/most_dangerous_exploits/

Security experts rate the world's most dangerous exploits

Pass the hash...

By Dan Goodin

Posted in Security, 24th April 2009 23:24 GMT

Criminal hackers continue to penetrate many more company networks than most administrators care to admit, according to two security experts who offered a list of the most effective exploits used to gain entry.

Topping the list is an attack dubbed super-flexible pivoting. It abuses Linux machines connected to a network's DMZ, or demilitarized zone, to bypass corporate firewalls and access sensitive resources on an internal network. The technique has already been used to steal vast amounts of data, including "millions of credit cards," said Ed Skoudis, a senior security consultant for InGuardians, a security company that frequently responds to major network breaches.

"If the bad guy can get control of one of your DMZ machines, he doesn't need to make inbound connections there anymore," Skoudis said during a panel at the RSA security conference. "Instead, he can make outbound connections that effectively give him inbound access on your internal network."

Another powerful exploit Skoudis is seeing frequently is the evolution of an attack known as pass the hash, which is used to penetrate Windows servers. Windows authentication works by checking a user's cryptographic hash, rather than password. Attackers can steal the hash by exploiting a simple unpatched browser or application vulnerability and then injecting it into the memory of the Windows box.

Although pass the hash has been around for a decade, the attacks have remained successful. That's in part thanks to a proliferation of software that streamlines the exploit. Examples include this download from Core Security, or this one from JoMo-kun. Nessus and Metasploit also have modules that perform the attacks.

Skoudis was joined by Johannes Ullrich, the CTO of the SANS Internet Storm Center. Together, they presented their list of the world's most dangerous new attack techniques and ways organizations can protect themselves against them.

"The real big problem here is user education," Ullrich told a standing-room audience. "And user education is more than going to the user and saying don't click on it. User education also means getting your own house in order."

Too many organizations are still failing to patch applications such as Adobe's Flash and Reader, he added. In other cases, they aren't teaching employees how to avoid social-engineering attacks on social networking sites and elsewhere.

Other dangerous exploits include:

The take-away is that admins should assume they've already been hacked.

"I believe that a determined but not necessarily well-funded attacker can pretty much break into any organization," Skoudis said. "If you think it's less than 50 percent, I think you need to look a little more carefully." ®