Watch out for the Invalid worm

Yet again a bogus Microsoft Security Bulletin is being used to harbour a mass mailing virus.

Dubbed the Invalid worm, this mass mailing virus randomly encrypts executable files, effectively rendering them unusable.

Only last month a variant of the destructive Leave worm was using the same method of propagation, when it was doing the rounds as a fake Microsoft security bulletin.

The Invalid worm virus appears in an email pretending to be from Microsoft Technical Support. The subject line of the message is along the lines of "Invalid SSL Certificate".

The body of the message contains text which tries to socially engineer a user into running an attached executable, sslpatch.exe.

This is done under the pretence that it will secure their machine against a buffer overrun in Internet Explorer, which would allow a hacker to attack their computer.

Once activated, the virus will scan the user's hard drive for all files featuring a '.ht' extension. It will then scan these files for email addresses and send itself to all the addresses it finds.

Most antivirus companies have already released an update to protect against this virus. It is available from the relevant vendor's website.