A computer virus has infected more than 10,000 machines and directed them to connect with and attempt to overwhelm online forums critical of the ruling Vietnamese Communist Party, security researchers said on Thursday.
The resulting denial-of-service attacks on a handful of sites show how such programs are increasingly being used to target opposition voices.
Similar attacks have been waged on anti-Russian sites operated from conflict zones in the Caucuses and on some more mainstream sites run by politicians at odds with the Kremlin.
Researchers at SecureWorks, who dubbed the new virus Vecebot, said they couldn’t prove that it was unleashed by the government or someone working for it. Such software is rarely traced to an author.
But they noted a piece of interesting timing. On Oct. 19, a Vietnamese blogger using the name Dieu Cay was to be released after serving a 30-month sentence.Vecebot could have been released ahead of that date, with a view toward shutting down sites that would have been likely to celebrate his return to freedom.
As it happened, the blogger was kept in jail on new charges. But it’s easy to imagine that the opposition sites might have complained about that turn of events-were they functioning well enough to do so.

