Trusteer, a leading security firm, released a warning for Spear-Phishing email attacks disguised as linked in invitations.
The fake email invitation is nearly identical to the real email invitation.
If you click on the fake invitation you are directed to a malware site trying to look like salesforce.com. The url they send you to is salesforceappi.com. If you visit this site, there is a very good chance you will get infected.
If you've recently accepted a linked in invitation, look at your browser history to see if you can find salesforceappi in the history. If you find this URL in your history, you need to get your computer cleaned. That may take some time, and even a visit to a local professional, so in the meantime do the following:
Print your browser history in chronological order from the time of visiting salsforceappi.
If you use your computer for business, contact your employer's IT or Loss Prevention department and explain the situation. If you have access to financial accounts, be sure they take action and change passwords accordingly.
Until the computer is cleaned or re-installed, don't be tempted to use your computer without the Live CD. The malware installed by this site is particularly hard to remove, and most likely includes a keylogger. If you're computer is running windows Vista or XP, consider this a good opportunity to do a clean install of Windows 7 and maybe even just upgrading to a new hard-drive.