A newly-discovered botnet is 'practically indestructible', security researchers say.
TDL-4 is the rootkit component of the TDSS malware, which has been around since 2008. But in the three months since it hit the scene, it's sucked in more than four and a half million PCs around the world. About a third are based in the US.
And in this, its latest incarnation, it has the cheek to include its own version of an anti-virus capability, which scans slave machines for software that could enable it to be taken over by another botnet.