A team of journalists and security experts from the BBC said that it has managed to purchase itself a botnet containing more than 22,000 infected PCs.
The network was constructed as part of an investigation into cybercrime by the television programme Click. The network said that it obtained access to the infected systems by purchasing information from cybercriminals in chat rooms.
After assembling the botnet, the researchers tested it out by ordering the infected machines to spam a pair of test e-mail accounts. A denial of service attack was also performed on a test website .
The network said that the botnet has since been disabled and the infected users have all been notified by the BBC and provided with security tips to prevent further infection.
The rise of botnets has been well documented and observed by security experts in recent years.
Massive botnets such as Storm controlled hundreds of thousands of infected machines at their peak and were used not only by their builders, but also leased out to other cycbercriminals for spam runs and online attacks.
While the BBC's botnet was modest in comparison to those infections, experts say that the experiment was still dangerous, and possibly illegal.
"This is clearly an unauthorised modification of computer data, and is, to my mind, a breach of the Computer Misuse Act," wrote Sophos senior security consultant Graham Cluley.
"The law says you can't mess around with other people's computers without authorisation. The BBC and PrevX did not have the permission of the computer users to send those spam mesages."
"Sending spam from someone else's computer obviously gobbles up bandwidth and will use up system resources. Even if the BBC felt the impact would be minimal, it doesn't make it right."
The BBC plans to air the segment on the March 14 episode of Click.