Conficker.C is a worm which exploits a vulnerability in the Windows Server Service which allows remote code execution. It is the vulnerability MS08-067.
If the system date is after January 1, 2009, it will try to connect to a certain website in order to download and run another type of malware in the affected computer.
On the one hand, it reduces considerably the protection level of the computer, as it prevents the user and the computer from connecting to many websites related to antivirus companies.
On the other, it uses weak passwords to access the user accounts in order to modify their security policies.
Conficker.C spreads by exploiting the vulnerability MS08-067. In order to do so, it sends malformed RPC requests to other computers in which it attempts to enter a copy of itself. Additionally, it spreads through shared and removable drives.
It is highly recommended to download and apply the security patch for the vulnerability MS08-067. Click here to access the web page for downloading the patch.