The email, sent from a bogus email address, urges the recipient to join the senders' network on the professional social network:
Clicking on the "Allow" button or the link beside it takes victims to a website sporting the "Please wait a moment…You will be forwarded…" message.
What they don't know is that the website hosts the Blackhole exploit kit which, while they wait, bombards their machine with exploits for a number of flaws in popular and ubiquitous software.
Afterwards they are sent to another website where they are urged to download and install a plug-in. As expected, the plug-in is actually the Cridex information-stealing Trojan.
Users are advised to be careful with email invitations such as these. When in doubt, it's always best to log into your social networking account and check the claim, but do it by entering the site's URL in the browsers' address bar and not by following links included in the emails.