SAN FRANCISCO – An obnoxious computer program that barged into Twitter Inc.'s mishmash of Internet chatter served as another reminder of the challenges facing the rapidly growing service.
The nettlesome program, known as a worm, targeted Twitter's network with four different attacks starting early Saturday and ending early Monday, according to Twitter co-founder Biz Stone.
The worm was set up to promote a Twitter knockoff, StalkDaily.com. It displayed unwanted messages on infected Twitter accounts, urging people to visit the Web site.
The worm was designed to automatically reproduce itself once its links were clicked on, but it didn't filch any personal information from the more than 6 million people with Twitter accounts, Stone wrote in a posting about the incident. Nearly 10,000 Twitter messages, known as "tweets," had to be deleted to contain the potential damage.
"We are still reviewing all the details, cleaning up and we remain alert," Stone reassured Twitter's audience.
Michael "Mikeyy" Mooney, a 17-year-old high school student who created StalkDaily, acknowledged unleashing the worm in a Monday interview with The Associated Press. Besides wanting to promote his Web site, Mooney said he wanted to expose Twitter's weaknesses.
"I really didn't think it was going to get that much attention, but then I started to see all these stories about it and thought, 'Oh my God,' " said Mooney, who lives in Brooklyn, N.Y. He first confessed his responsibility for the worm to BNONews.com.
Mooney began having second thoughts about what he had done after reading a part of Stone's posting indicating that Twitter might pursue legal action against its tormenter. In a Monday e-mail sent to the AP, Stone said he didn't know whether Twitter will go after Mooney.
"If I get hit with a lawsuit, I am going to have major regrets and a big brick on my back," Mooney said. "I am backing off now. Twitter ignored its vulnerability (to worms) so I am hoping they can just ignore me now."
In the mean time, Mooney is retooling StalkDaily.com to accommodate more users. He has temporarily closed the site after getting swamped by the traffic triggered by his worm.
The trouble with Mooney represents another rite of passage for San Francisco-based Twitter, which has emerged a popular way to communicate on the Web and mobile phones since its debut three years ago.
Twitter's system, which limits messages to 140 characters, is used to broadcast both mundane and tantalizing information by a diverse group of users that include teenagers, celebrities, news agencies, politicians, police departments and companies.
Twitter's broadening reach makes it an inviting target for mischief makers and scam artists. Two of the Internet's biggest online hangouts, Facebook and MySpace, both have had to grapple with similar threats.
The widening usage also occasionally overwhelms the free service, whose 30 employees have been subsisting on about $55 million in venture capital until Stone and fellow co-founder Evan Williams come up with a way to generate revenue.
Although it doesn't break down as frequently as it did in its early days, Twitter periodically remains inaccessible because its computer servers can't handle all the traffic.
Such challenges have spurred speculation that Twitter eventually will be sold to a larger Internet company. Twitter already spurned a $500 million buyout offer from Facebook Inc. There also have been unsubstantiated reports that Internet search leader Google Inc. is eyeing a possible bid for Twitter.
Both Williams and Stone have said they intend to build Twitter into a profitable, independent company.