Here are the steps in the process:

1. Cybercriminals purchase Facebook user names and passwords on websites at a cost of $75 to $200 per 1000 matching pairs.

2. Cybercriminals enter accounts and get access to friends, emails, dates of birth, mother’s maiden names, home towns, and vital information from profiles and postings to start online conversations.

3. Messages are sent to friends with information of interest (based on postings) that include a link to a website that results in a malicious executable file being placed on the recipient’s PC.

4. Executable files contain keystroke loggers that capture all user keystrokes on a periodic basis that are emailed to free Gmail or Hot Mail accounts that are set up by the Cybercriminal.

5. Eventually, the user logs into the employer’s network through VPN or Citrix and the cybercriminal captures the user name and password.

6. The cybercriminal enters the corporate network and probes for weaknesses such as those caused by failure to update security patches.

7. A vulnerable server is found and breached resulting in the hacking of confidential information.

Source: http://www.usatoday.com/NEWS/usaedition/2010-03-04-1Anetsecurity04_CV_U.htm?csp=N009

Attackers use “botnets” or networks of “zombie” personal computers, which they have infected with a virus.  Denial of service comes in to play when the controlled computers are instructed to contact target websites on a repeated basis until such target websites are overwhelmed. 

More sophisticated e commerce websites protect against these attacks by using special software that detects and shuts down suspicious traffic.

Protect your computers!  Viruses often attack and there are no apparent signs that your computer has been contaminated.  Software is available to identify and flag dubious traffic flow.  Many companies offer a free scan, so make sure you update your antivirus software and run regular scans.  Also, potentially affected businesses should purchase Cyber Liability insurance to protect against this risk.

Source: http://www.msnbc.msn.com/id/31803381/ns/technology_and_science-security/