Servers running the Koobface botnet have stopped responding after Jan Droemer and Dirk Kollberg working with Facebook named and shamed five suspected ringleaders.

After more than two years of work, a pair of researchers on Tuesday published the names, aliases and photographs of a gang they accused of running a criminal enterprise known as Koobface that had primarily targeted Facebook after it cropped up in 2008.

Kollberg's employer, the UK anti-virus software maker Sophos, said that some computers used to control Koobface had previously been disabled and it had not spread through Facebook connections since early last year. But the ad continued to target other social networks as a long-running FBI probe failed to result in arrests in Russia.

But it is clear that as result of the exposure the botnet is down. Droemer and Kollberg said that they had planned to hold off on publishing their data until coppers captured the suspects. They released it earlier, with Facebook's blessing, after one of those suspects, who goes by the alias "Krotreal," was named last week by another researcher.