Judging from their techniques and from his previous research, Thompson believes the attackers are college students based in China and that they may be the same group that notoriously hacked the Web sites of the Miami Dolphins and Dolphin Stadium ahead of the 2007 Super Bowl football championship.

Earlier this year, a similar attack compromised more than 1.5 million Web pages, Kaspersky said. "Things are still developing, and the similar nature of the malicious programs used in both attacks lead us to think that this new wave of attacks is potentially pretty serious."