Program for Hackers Is Causing Concerns

Computer security experts in both government and the private sector are monitoring the emergence of a new, sophisticated hacker program that connects infected computers to far-flung peer-to-peer file-sharing networks.

By some estimates, hundreds of thousands of computers running Microsoft Corp.’s Windows operating system already have been infected worldwide. The program, software code that security researchers have dubbed “Phatbot,” allows its authors to gain control over computers and link them into file-sharing networks that can be used to send large amounts of spam e-mail messages or to flood websites with data in an attempt to knock them offline.

The new hacker threat caught the attention of cyber security officials at the Department of Homeland Security, prompting the agency to send an alert last week to a select group of computer security experts.

According to computer security experts, Phatbot can evade antivirus software, steal America Online login names and passwords, harvest e-mail addresses from the Web for spam purposes, and sniff Internet network traffic for small computer files, or cookies, that contain personal data used by the PayPal online payment system.

Phatbot is “a virtual Swiss army knife of attack software,” said Vincent Weafer, senior director of security response at Cupertino, Calif.-based Symantec Corp.