Targeted hacker attacks, such as the one believed to have caused the massive credit card security breach disclosed this month, are low tech and well understood. Nevertheless, they are extremely hard to stop, IT managers said last week.

The growing problem is compelling companies to implement defense strategies that emphasize data-level monitoring and protection mechanisms and stronger user authentication to supplement their network intrusion-detection and egress-filtering measures.

"We"re clearly seeing a trend away from broadcast attacks to much more targeted and much more sophisticated types of attacks," said Andreas Wuchner-Bruhl, head of global IT security at Novartis Pharma AG, a drug maker in Basel, Switzerland. "Dealing with it is much tougher."

That"s because "the cons in the attacks are so much better customized" for the specific companies they target, said Lloyd Hession, chief information security officer at BT Radianz, a New York-based provider of telecommunications services to the financial industry. "The chances of them being successful are much higher" than in large-scale attacks, he said.

MasterCard International Inc. on June 17 disclosed the security breach at CardSystems Solutions Inc., a provider of payment services for credit card companies [QuickLink a6230]. The hacking incident exposed up to 40 million credit cards to the hackers, MasterCard said.

A malicious script placed in a computer that stored data at a CardSystems facility is believed to have been used to steal the data.

The breach was seen by security experts as further evidence of a growing trend away from mass-mailing worms and viruses to more-tailored attacks directed against specific high-value targets.

Because such targeted attacks generate much less traffic than mass attacks, they are a lot harder to detect using traditional antivirus and e-mail filtering tools, said Matt Kesner, chief technology officer at Fenwick & West LLP, a law firm in Mountain View, Calif.

"The problem is that the antivirus, antispam and firewall companies are all geared to respond to major outbreaks that hit tens of thousands of computers," Kesner said. A smaller attack, he added, "may not be noticed by those vendors. That leaves most companies very vulnerable."

Often, the attackers use social engineering tricks -- via spoofed e-mails and Web sites -- to get users to unknowingly install malicious code. Targeted messages are also used to get users to part with IDs and passwords that are then used to gain access to critical systems and information, said Jason Jones, a webmaster at a private university in Texas that he asked not be named.

In a test, Jones and his team at the university successfully collected authentication credentials from over 90 percent of targeted individuals by using spoofed e-mail and Web pages designed to look like they were from the university"s IT security team.

"The credentials were enough for us to remotely gain access to all of the data we wanted, completely undetected," he said.

Dealing with targeted hacking "very much requires an in-depth defense" strategy, said Kevin Houle, senior member of the technical staff at Carnegie Mellon University"s CERT Coordination Center.

Apart from ensuring that antivirus signatures, patches and e-mail filters are updated, it"s also key for IT operations to implement tools for detecting anomalous network behavior, Houle said. "What we are advocating is the ability to go out and look for patterns on the network," he said.

Knowing what"s going out of the network is as important as keeping track of what"s coming in, so it"s a good idea to implement egress-filtering tools, Hession said. Similarly, database-level access-monitoring and encryption can help mitigate the impact of such targeted attacks, analysts and users said.