Internet security researchers on Thursday warned that hackers have caught on to a "critical" flaw that lets them control traffic on the Internet.
An elite squad of computer industry engineers that labored in secret to solve the problem released a software "patch" two weeks ago and sought to keep details of the vulnerability hidden at least a month to give people time to protect computers from attacks.
"We are in a lot of trouble," said IOActive security specialist Dan Kaminsky, who stumbled upon the Domain Name System (DNS) vulnerability about six months ago and reached out to industry giants to collaborate on a solution.
"This attack is very good. This attack is being weaponized out in the field. Everyone needs to patch, please," Kaminsky said. "This is a big deal."
DNS is used by every computer that links to the Internet and works similar to a telephone system routing calls to proper numbers, in this case the online numerical addresses of websites.
The vulnerability allows "cache poisoning" attacks that tinker with data stored in computer memory caches that relay Internet traffic to its destination.
Attackers could use the vulnerability to route Internet users wherever the hackers wanted, no matter what website address is typed into a web browser.
The threat is greatest for business computers handling online traffic or hosting websites, according to security researchers.
The flaw is a boon for "phishing" cons that involve leading people to imitation web pages of businesses such as bank or credit card companies to trick them into disclosing account numbers, passwords and other information.
"I was not intentionally seeking to cause anything that could break the Internet," Kaminsky said Thursday during a conference call with peers and media. "It's a little weird to talk about it out loud."
Kaminsky built a web page, www.doxpara.com, where people can find out whether their computers have the DNS vulnerability. As of Thursday, slightly more than half the computers tested at the website still needed to be patched.
"People are spending tens of thousands of hours getting this patch out the door," Kaminsky said.
The US Computer Emergency Readiness Team (CERT), a joint government-private sector security partnership, is among the chorus urging people to quickly protect computers linked to the Internet.
"Just like you should wear a seat belt going down the road to be safe in a car accident, the same applies here," said Jerry Dixon, a former director of cyber security at the US Department of Homeland Security.
"The patch is your seat belt. The exploit is out there and you definitely need to take precautions. Now is not the time to keep waiting."
Two "exploits," software snippets that take advantage of the vulnerability, have been unleashed on the Internet in the past 24 hours, Securosis analyst Rich Mogul said during the conference call.
"The threat is there," Mogul said.