Hacker groups such as Anonymous and Lulz Security may need to be monitored more closely in the event they are assisted by other hackers with higher skill levels and decide to strike critical infrastructure.
The warning (PDF) comes from the NCCIC (National Cybersecurity and Communications Integration Center), which is part of the U.S. Department of Homeland Security.
"Some members of LulzSec have demonstrated moderately higher levels of skill and creativity that include using combinations of methods and techniques to target multiple networks," according to the six-page advisory. "This does not take into account the possibility of a higher-level actor providing LulzSec or Anonymous more advanced capabilities."
Anonymous and a splinter group known as LulzSec have wreaked havoc against government and business websites and servers, from low-level defacement of websites up to more sophisticated actions such as stealing sensitive data.
The agency categorized the attacks as "rudimentary" and associated with youths known as "script kiddies" for their use of simple tools to hack. But law enforcement agencies in countries such as the U.S., U.K., Spain, and the Netherlands have made arrests in attempts to stem their activities.
On Monday, U.K. prosecutors charged an 18-year-old man with five offenses and said that he is "Topiary," a spokesman for Anonymous who ran a prolific Twitter account antagonizing law enforcement and promoting the groups' cybermischief. Jake Davis, of the Shetland Islands, was freed on bail and is not allowed to use a computer.
Anonymous and LulzSec have targeted defense contractors such as HBGary and ManTech as well as the U.S. Central Intelligence Agency and the U.K. Serious Organised Crime Agency. Private industry targets included Fox.com and SonyPictures.com.
Anonymous coordinated a large campaign in defense of WikiLeaks in December 2010. The websites of MasterCard, Visa, PayPal and the Swiss Bank PostFinance were subjected to denial-of-service attacks after they stopped processing payments to WikiLeaks following the whistle-blowing site's release of secret U.S. diplomatic cables.
The NCCIC wrote that the groups often do "a significant amount of reconnaissance" before attacking an organization, heavily using social media outlets such as Twitter and Facebook to announce their targets.
Those warnings can allow computer security experts to bolster their defense, the NCCIC wrote. The U.S. government expects further attacks on its infrastructure.
"Future attacks are likely to continue but will likely remain limited in scope due to a lack of advanced capabilities," the NCCIC wrote. "These attacks are also likely to target the Federal government and critical infrastructure sectors, particularly in response to publicized events relating to civil liberties, cyber security, or allegations of censorship (online or otherwise)."
The Twitter account "AnonymousIRC" acknowledged the NCCIC's warning: "Now they know what Lulz are," the group wrote, using the Internet term for "laugh out loud."
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