FBI: Hackers Penetrated E-Commerce Sites

March 8 -- The FBI says organized hacker groups based in Russia and Ukraine have penetrated the e-commerce sites of hundreds of U.S. businesses, stealing customer proprietary information, including more than a million credit card numbers.

According to an FBI warning issued today, the hackers scanned e-commerce sites for vulnerabilities, exploited them, and then downloaded personal information of customers.

The hackers then contacted the victimized companies, notified them of their intrusion, and offered to fix the problems for a fee. If the companies didn't respond, the hackers issued threats and tried to extort money from them, the FBI said.

The FBI and U.S. Secret Service have launched investigations into alleged attacks against 40 companies in 20 states, and estimate more than 1 million credit card numbers have been stolen.

Warnings To Tighten Security

FBI officials say the hackers have been exploiting vulnerabilities in unsecured Microsoft Windows NT operating systems.

The FBI and Microsoft have been issuing warnings about installing security patches for the operating systems since 1998, but many companies apparently have not heeded the calls for concern.

ABCNEWS' Pierre Thomas contributed to this report.