Eli the Computer Guy

Info

• Level: Intermediate
• Presenter: Eli the Computer Guy
• Date Created: November 1, 2010
• Length of Class: 45 Minutes

Tracks

• Hacking
• Computer Security /Integrity

Prerequisites

• Knowledge of TCP/IP and Domain Name Resolution

Purpose of Class

• This class teaches students how use DNS to redirect computer or network users to alternate websites or servers for security or malicious purposes.

Topics Covered

• How DNS Works
• Editing the HOSTS file
• Alternate Public DNS
• Planning a DNS Hack
• Reasons to Hack DNS

Class Notes

1. Introduction
   1. DNS resolves Domain Names to IP Addresses
   2. Warning: Use at your own risk
2. DNS
   1. HOSTS file is the local file that resolves Domain Names
   2. Windows Location = C:\Windows\System32\drivers\etc
   3. Example = 10.1.10.2              www.elithecomputerguy.com
   4. In Vista/ Windows 7 First Open Notepad using “Run as Administrator” and then open the HOSTS file.  Otherwise you will not be able to save your edits.
   5. Computers FIRST try to Resolve a Domain Name with the HOSTS file, they then Go To the LOCAL DNS Server, and then they Query the PUBLIC DNS Server.  If any server has a record the computer does not ask any other sources.  SO if the HOSTS file has a record the computer uses that record and stops.
3. Using Alternate DNS
1. You do not have to use the Public DNS IP Addresses that your ISP gave you.  You can use Alternate Public DNS Servers.
2. The benefit of using a server like OpenDNS.org is that they will prevent Domain Names for malicious websites from resolving.  This is a HUGE security tool.
3. You can create your own Public DNS Server for Good/ Bad Purposes.
4. The DNS Attack
1. HOSTS file can be compromised either through manual editing, or through scripting.  If users are logged in as USERS vs. ADMINISTRATORS there is far less chance that a script will be able to modify the HOSTS file.
2. By Wardriving or Plugging Into an Unsecured Network Jack You May be able to Hack the DNS Server.  Routers/ Modems with default passwords are easy to Hack.
3. A clever, well disguised DNS Hack is very difficult to detect once it has been successfully implemented, and it is moderately difficult to circumvent if it is done by a network administrator to secure a network.
5. Final Thoughts
1. Hacking DNS is the EASIEST way to either protect or attack a network or computer

Resources

Eli the Computer Guy (437 Posts)

Eli the Computer Guy has 16 years experience in technology being the guy to fix "it". From the Army, to building out new satellite offices for the enterprise, to running his own shop with 9 full time employees Eli has real world experience with almost all systems that technicians will be working with. Eli has 1600 hours of formal technical beyond his Bachelors Degree in Criminal Justice on technologies ranging from Avaya PBX/ Audix to Microsoft, Red Hat Linux, MySQL, Cisco and much more.