To the best of my knowledge, it looks for a Java vulnerability and if it finds it, it launches a program which then checks your Adobe Acrobat version. If Acrobat has a vulnerability, it launches Acrobat and tries to run a program that downloads malware onto your machine.
The best way to block it in my opinion is to make sure you have up to date Internet Security Software, not just anti-virus. I'm running Norton Internet Security 2011. The free anti-virus programs are worth what you pay for them , IMO.
Also, you can block the IP I gave above in your router. Hope this helps.