Hacker Tool Poses Threat, Experts Say

Computer security experts said Wednesday that they have discovered a new, rapidly spreading program that hackers could use to shut down Web servers via a popular instant-messaging platform.

The hacker tool, named Voyager Alpha Force, has been used to infect more than 300 computers, said Elias Levy, chief technology officer at SecurityFocus.com.

Although the infected computers have not yet been used to shut down Web servers, they easily could be, Levy said.

In such an attack, software that has been sneaked onto computers is instructed to send so many requests to a targeted Web server that it overloads it, rendering it inaccessible to legitimate requests.

The new tool infects computers running Microsoft Corp.’s SQL Server database software that has not been configured to change the blank default password, Levy said.

Levy recommends changing the default passwords and putting the server behind firewall software to block unauthorized access.