Computer Security Fundamentals

by Chuck Easttom

Chapter 6 Techniques Used by Hackers

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Chapter 6 Objectives

Understand the basic methodology used by hackers

Be familiar with some of the basic tools Understand the hacking mentality

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Introduction

Basic Terminology Reconnaissance

Passive Scanning

Netcraft.com

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Archive.org

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Port Scanning

NMap

NMAP Flags

-O detects operating system -sP is a ping scan -sT TCP connect scan -sS SYN scan -sF FIN scan -sX XMAS Tree scan -sN NULL scan -sU UDP scan -sO Protocol scan -sA ACK Scan -sW Windows scan -sR RPC scan -sL List/DNS scan -sI Idle scan

-Po Don’t ping

-PT TCP ping

-PS SYN ping

-PI ICMP ping

-PB TCP and ICMP ping

-PM ICMP netmask

-oN Normal output

-oX XML output

-oG Greppable output

-oA all output

-T timing

-T0 paranoid

-T 1 Sneaking

-T 2 Polite

-T 3 Normal

-T 4 Aggressive

-T 5 Insane

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Ping Scan

The ping scan sends a single ICMP echo request from the source to the destination device. A response from an active device returns an ICMP echo reply, unless the IP address is not available on the network or the ICMP protocol is filtered.

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Connect Scan

Fully connect to the target ip address and port. Does a complete TCP handshake. This is the most reliable but will absolutely be detected.

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Syn Scan

Sends syn (synchronize) requests to the target to gather information about open ports without completing the TCP handshake process. When an open port is identified, the TCP handshake is reset before it can be completed. This technique is sometimes called to as "half open" scanning.

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Fin Scan

Sends a FIN (or finish) packet to target. If that port is not listening, no response. If it is listening an error response is received.

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Enumeration

Sid2User Cheops (Linux only) UserInfo UserDump DumpSec Netcat NBTDump

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Cain and Abel

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SQL Injection

One of the most common attacks Depends on knowledge of SQL Basics are easy Versatile and can do a lot more than many

realize

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What Is SQL? A relational database contains one or more tables

identified each by a name. Tables contain records (rows) with data. For example, the following table is called "users" and

contains data distributed in rows and columns: SQL (Structured Query Language) uses commands like

such as SELECT, UPDATE, DELETE, INSERT, WHERE, and others. Example:SELECT * FROM tblUsers WHERE USERNAME = ‘admin’

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More on SQL

Web sites are written in some programming language such as PHP, ASP, JSP, ASP.net. Those programming languages have their own syntax (NOT SQL). So programmers put the SQL into their code in strings. So lets say you type your username into a text field called txtUsername and your password into a text field called txtPassword. The code in their program has to put SQL statements into a string and append whatever you entered in those two text fields. It will look something like this:

string sSQLstatement; sSQLstatement = “SELECT * FROM tblUSERS WHERE UserName = ‘ “

+ txtUsername.Text +’” + “ AND Password = ‘” + txtPassword.Text +”’”;

so the string will contain

‘SELECT * FROM tblUSERS WHERE UserName =‘admin’ AND Password = ‘password’’;

However whatever you type in, gets put into the text field.

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SQL Script Injection

Single quote added to password: Add the following to the username box and the password:

' or ‘1' =‘1 OR ' or 'a' ='a Also try password’ or (1=1) Or people try anything' OR 'x'='x or people try password:’1=1- - Try using double quote (") if single quote (') is not working

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What Does This Cause?

Well you would have had

‘SELECT * FROM tblUSERS WHERE UserName =‘admin’ AND Password = ‘password’’;

Instead you have

‘SELECT * FROM tblUSERS WHERE UserName =‘' or ‘1' =‘1

’ AND Password = ‘' or ‘1' =‘1

’’;

So now it says to get all entries from table = tblUsers if the username is ‘’ (blank) OR IF 1 =1. And if password = ‘’ (blank) OR IF 1=1!

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Cross Site Scripting

An attacker injects client-side script into web pages viewed by other users. The term cross-site scripting originally referred to the act of loading the attacked, third-party web application from an unrelated attack site, in a manner that executes a fragment of JavaScript prepared by the attacker in the security context of the targeted domain

Essentially you enter scripts into an area that other users interact with. So that when they go to that part of the site, you have your own script run, rather than the intended Web site functionality. This can include redirecting them.

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OphCrack- How It Works

Download OphCrack and burn the image to a CD.

Put the CD in the target computer and boot through CD.

It boots as Linux, grabs the Windows password file, and then uses cracking tools to crack that file and produces a text file with username and passwords.

You cannot even consider yourself a hacker without this tool in your toolkit.

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