Older versions of Windows receive new fix to stop WannaCry attacks

The company said it had seen "no exploitation" before the update, but it was "very likely" that the malware authors would use this security hole. Some systems with authentication at the network level have a partial defense because they require identification information before the vulnerability is usable.

There is no doubt about why Microsoft does this. WannaCry has had a devastating impact on PCs around the world, including the UK healthcare system, and Microsoft does not want to risk contributing to the problem by leaving the systems unpatched. There is no guarantee, however, that this will prevent a crisis. Malware like WannaCry tends to spread precisely because companies and institutions are reluctant to update their systems and risk compromising important software. This will only be effective if Microsoft can convince customers that patches are too important to ignore.