8

Chapter 2

Exploit

An 

exploit

 is the means by which an attacker, or pen tester for that matter, takes 

advantage of a flaw within a system, an application, or a service. An attacker 
uses an exploit to attack a system in a way that results in a particular desired 
outcome that the developer never intended. Common exploits include buffer 
overflows, web application vulnerabilities (such as SQL injection), and con-
figuration errors.

Payload

A 

payload

 is code that we want the system to execute and that is to be selected 

and delivered by the Framework. For example, a 

reverse shell

 is a payload that 

creates a connection from the target machine back to the attacker as a Win-
dows command prompt (see Chapter 5), whereas a 

bind shell

 is a payload that 

“binds” a command prompt to a listening port on the target machine, which 
the attacker can then connect. A payload could also be something as simple as 
a few commands to be executed on the target operating system.

Shellcode

Shellcode 

is a set of instructions used as a payload when exploitation occurs. 

Shellcode is typically written in assembly language. In most cases, a command 
shell or a Meterpreter shell will be provided after the series of instructions 
have been performed by the target machine, hence the name.

Module

A 

module

 in the context of this book is a piece of software that can be used by 

the Metasploit Framework. At times, you may require the use of an 

exploit 

module

, a software component that conducts the attack. Other times, an 

auxiliary module

 may be required to perform an action such as scanning or 

system enumeration. These interchangeable modules are the core of what 
makes the Framework so powerful.

Listener

A 

listener 

is a component within Metasploit that waits for an incoming connection 

of some sort. For example, after the target machine has been exploited, it may 
call the attacking machine over the Internet. The listener handles that connec-
tion, waiting on the attacking machine to be contacted by the exploited system.

Metasploit Interfaces

Metasploit offers more than one interface to its underlying functionality, 
including console, command line, and graphical interfaces. In addition to 
these interfaces, utilities provide direct access to functions that are normally 
internal to the Metasploit Framework. These utilities can be invaluable for 
exploit development and situations for which you do not need the flexibility 
of the entire Framework.