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Hands-On Ethical Hacking and Network Defense
Second Edition
Chapter 3 Network and Computer Attacks

Objectives
• After this lecture and completing the exercises, you will be able to :
– Describe the different types of malicious software and what damage they can do – Describe methods of protecting against malware attacks – Describe the types of network attacks – Identify physical security attacks and vulnerabilities

Hands-On Ethical Hacking and Network Defense, Second Edition

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Malicious Software (Malware)
• Network attacks prevent a business from operating
– Malicious software (malware)
• Virus • Worm • Trojan program

– Goals
• • • • Destroy data Corrupt data Shutdown a network or system Make money
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Hands-On Ethical Hacking and Network Defense, Second Edition

Viruses
• Virus attaches itself to a file or program
– Needs host to replicate – Does not stand on its own – No foolproof prevention method

• Antivirus programs
– Detection based on virus signatures
• Signatures are kept in virus signature file • Must update periodically • Some offer automatic update feature

Hands-On Ethical Hacking and Network Defense, Second Edition

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Table 3-1 Common computer viruses

Hands-On Ethical Hacking and Network Defense, Second Edition

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Viruses (cont’d.)
• Encoding using base 64
– – – – – – – – Typically used to reduce size of e-mail attachments Also, used to encrypt (hide) suspicious code. Represents zero to 63 using six bits A is 000000… Z is 011001 Create groups of four characters Convert decimal value of each letter to binary Rewrite as three groups of eight bits Convert binary into decimal
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• Converting base-64 strings to decimal equivalent

Hands-On Ethical Hacking and Network Defense, Second Edition

Hands-On Ethical Hacking and Network Defense, Second Edition

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Viruses (cont’d.)
• Base-64 decoders
– Available for purchase

• Shell
– Executable piece of programming code (references executable DLL files, e.g. User32.dll, Kernel32.dll) – Creates...

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