Bill has successfully executed a buffer overflow against a Windows IIS web server. He has been able to spawn an interactive shell and plans to deface the main web page. He first attempts to use the "Echo" command to simply overwrite index.html and remains unsuccessful. He then attempts to delete the page and achieves no progress. Finally, he tries to overwrite it with another page again in vain.

What is the probable cause of Bill’s problem?

A.
The system is a honeypot.

B.
There is a problem with the shell and he needs to run the attack again.

C.
You cannot use a buffer overflow to deface a web page.

D.
The HTML file has permissions of ready only.

Explanation:
The question states that Bill had been able to spawn an interactive shell. By this statement we can tell that the buffer overflow and its corresponding code was enough to spawn a shell. Any shell should make it possible to change the webpage. So we either don’t have sufficient privilege to change the webpage (answer D) or it’s a honeypot (answer A). We think the preferred answer is D