A rootkit is a collection of computer software, typically malicious, designed to enable access to a computer or areas of its software that would not otherwise be allowed (for example, to an unauthorized user) while at the same time masking its existence or the existence of other software. A bootkit is similar to a rootkit except the malware infects the master boot record on a hard disk. Malicious software such as bootkits or rootkits typically require administrative privileges to be installed.
Therefore, one method of preventing such attacks is to remove administrative access for local users.
A common source of malware infections is portable USB flash drives. The flash drives are often plugged into less secure computers such as a user's home computer and then taken to work and plugged in to a work computer. We can prevent this from happening by restricting or disabling access to USB devices.
Incorrect Answers:
A: Using a group policy to limit web access is not a practical solution. Users in a company often require Web access so restricting it will affect their ability to do their jobs.
B: Rootkits or Bootkits would not be caught by connecting to the network over a VPN so disabling VPN access will not help.
C: Removing full-disk encryption will not prevent Bootkits.
E: Bootkits are not caught by connecting to network resources using Telnet connection so disabling Telnet access to resources will not help.
F: Performing vulnerability scanning on a daily basis might help you to quickly detect Bootkits. However, vulnerability scanning does nothing to actually prevent the Bootkits.
References:
https://en.wikipedia.org/wiki/Rootkit