What steps can companies take to protect themselves?

The computer-security systems of many major corporations today are a Maginot line: Hackers are all too often overwhelming the defenders.

New forms of customized fake e-mails and other sophisticated programs can easily breach computer firewalls. Cyberthieves are devising new strains of spyware quicker than many companies can thwart them with antivirus software.

In the burgeoning world of Internet espionage, the advantage seems to be increasingly tipping toward the spies.

“Attackers’ capabilities are racing ahead while many companies don’t yet realize the full threat they face,” says Paul Williams, a cybersecurity expert who spoke at a recent oil-industry conference in Houston.

To redress the balance, experts offer several suggestions. One is for companies to become more zealous about monitoring critical information as it moves across their own networks. Often, companies are vigilant about setting up secure walls around their systems that try to prevent offending viruses and other spyware from getting in.

But they are usually less rigorous in monitoring key information that is going out of the network, which can be a window into nefarious activity that might be going on and who’s behind it, according to Daniel Geer, chief information security officer for In-Q-Tel, a nonprofit venture capital firm funded by the Central Intelligence Agency.

Dr. Geer, author of the book “Economics and Strategies of Data Security,” argues that rather than zeroing in on people, firms should first:

UIdentify critical data and then adopt systems so that you know how often the information is being accessed, by whom, and where it is going. Data that are valuable should be monitored at a level “in proportion to its value,” he writes.

UMake data security a principal focus of the company, not just an afterthought. That would include developing both surveillance and “interdiction” capability to be able to cut off access to key data — swiftly. This means built-in, rather than bolted on, security.

— Mark Clayton