How might a hacker cause a denial-of-service attack on an FTP 1D0-470
server?

A.
By executing a damaging program on the server

B.
By initiating an ICMP flood

C.
By initiating a broadcast storm

D.
By filling the server’s hard drive to capacity

Explanation:
When the space on the server is depleted, you can no longer upload files to the FTP server. If the FTP server is an upload server, a full disk becomes a problem because no more files can be written. A denial of service attack involves monopolizing all the resources so no legitimate user can use them. Here, the resource is disk space, and that is what has been monopolized. Depending on the location of the hard drive in relation to the Operating System and other tasks, filling the hard drive may even disable the FTP server and deny service on even downloads, and even possible crash of the entire server. This can happen when there is only one disk in the server, and the operating system comes to a halt due to lack of logging or paging space.
Incorrect Answers:
A: Execution of a damaging program on the server is caused by a virus. A FTP server cannot directly invoke a virus because even though the file containing the virus can be deposited on the server by an upload FTP, the file cannot be executed. FTP does not invoke any user code in the normal execution of the FTP services.
B: An ICMP flood would knock out the FTP server, and the increased traffic could also knock out the other servers on the subnet, and possibly connected subnets along the path. This question is trying to focus on a vulnerability specific to the FTP server itself.
C: A broadcast storm would knock out the FTP server and every other server on the LAN. This question is trying to focus on a vulnerability specific to the FTP server itself.