Government and industry security experts are expressing concern about the growing sophistication of Web page hacks by organised groups that have political agendas.
Such hackers may have already left behind malicious code that's capable of turning unsuspecting systems into time bombs for future distributed denial-of-service (DDOS) attacks.
These so-called zombie machines were a key part of the DDOS attacks against sites last February, including those of CNN and eBay.
The problem remains serious enough that the US government's Cyber Incident Coordination Group (CICG) - a newly formed group of select cyberintelligence experts from the US Central Intelligence Agency, the National Security Council, the Critical Infrastructure Assurance Office and the US Federal Bureau of Investigation - recently held a secure videoconference to discuss it.
The mission of the CICG is to coordinate the government's response to cyberincidents that may pose threats to national security.
Recent industry reports of "widespread infestation" of zombie computers and concern about the new generation of DDOS tools capable of exploiting always-on Internet devices and broadband connections prompted the meeting, said a member of the CICG.
National security officials are "very concerned" about the number of systems that may be infected with DDOS code, the CICG official said.
Ben Venzke, an analyst at Internet security and intelligence firm iDefense, has monitored the cyberconflict in the Middle East closely.
According to Venzke, hacker groups that have traditionally specialized in Web defacements, such as GForce Pakistan, are now reaching beyond defacements to more damaging activity.
For example, when GForce Pakistan recently defaced the Web site of the Indira Gandhi Centre for Atomic Research in India, the group made reference to "owning" the site and possibly stealing sensitive nuclear information.
"In the past, there might have been a tendency to write off defacements," said Venzke. "You need to step back and determine what other activity could be running in parallel. There may very well be more sophisticated elements trying to gain root access or launch DDOS attacks."
John Pescatore, a security analyst at Stamford, Conn.-based Gartner Group Inc., said "hactivism" and Web site vandalism are among the top problems that companies will confront in the coming years.
The security incidents that companies are likely to see include self-inflicted wounds from poor administration, viruses, targeted information theft by hactivists, and more sophisticated information warfare spillover from hostilities such as the Palestinian-Israeli conflict, Pescatore said.
"The more dangerous types are the subtle ones, where a single line of text is changed in a press release," said Diane Fraiman, a spokeswoman for Sanctum, a company that has helped defend Israeli government Web sites in their conflict in cyberspace against pro-Palestinian hackers.
"The cost to business, brand and customer loyalty can be devastating," said Fraiman. "We're seeing that happen now on a regular basis."
However, once the hacker breaks into the Web server and defaces a Web page, questions remain about the integrity of the rest of the system and the network it's connected to, said Fraiman.
Once you're in the Web application, "you have total control at that point of all the content sitting on the back-end of that system," she said.