You don't fix viruses with a patch file. If you actually have a virus, you need to clean the infection with a good antivirus program.
It could be a vulnerability patch for a security hole, but those are ALWAYS given on the official Windows Update site.
How did you get notified? I am guessing that this was in an email, from a place that claimed to be Microsoft, and they were offering the program (or a link to it) right there? If so, that's almost definitely a scam, even if the sender address looks legit. It's far more likely that the "patch" is actually a virus itself.
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