desktop pc computer security

IT Security AwarenessJanuary 24, 2011

MATC

Chapter 2Desktop Security

Security Awareness

Chapter 2Desktop Security

Objectives

After completing this chapter, you should be able to do the following:•Describe the different types of software and hardware attacks•List types of desktop defenses•Explain how to recover from an attack

Security Awareness, 3rd Edition 3

Attacks on Desktop Computers• Most attacks fall into two categories

– Malicious software attacks – Attacks on hardware


Malicious Software Attacks

• Malware – Wide variety of damaging or

annoying attack software– Enters a computer system

without the owner’s knowledge or consent

• Primary objectives of malware– Infect a computer system

with destructive software – Conceal a malicious action


Infecting Malware

• Viruses – Malicious program that needs a

‘‘carrier’’ to survive– Two carriers

• Program or document• User


Infecting Malware (cont’d.)• EVERY IT Security lecture must have a picture of a

padlock in it, somewhere• Viruses have performed the following functions:

– Caused a computer to crash repeatedly– Erased files from a hard drive– Installed hidden programs, such as stolen software,

which is then secretly distributed from the computer– Made multiple copies of itself and consumed all of the

free space in a hard drive– Reduced security settings and allowed intruders to

remotely access the computer– Reformatted the hard disk drive


Infecting Malware (cont’d.)• Types of computer viruses

– File infector– Resident– Boot– Companion– Macro– Polymorphic


Infecting Malware (cont’d.)• Worms

– Take advantage of a vulnerability in an application or an operating system

– Enter a system– Deposit its payload– Immediately searches for another computer

that has the same vulnerability


Infecting Malware (cont’d.)• Different from a virus

– Does not require program or user• Actions that worms have performed include

– Deleting files on the computer – Allowing the computer to be remote-

controlled by an attacker


Concealing Malware

• Trojan horse (or just Trojan) – Program advertised as performing one

activity but actually does something else– Typically executable programs that contain

hidden code that attacks the computer system


Concealing Malware (cont’d.)• Rootkit

– Set of software tools – Used to break into a computer, obtain special

privileges to perform unauthorized functions– Goal is not to damage a computer directly– Go to great lengths to ensure that they are

not detected and removed– Replace operating system commands with

modified versions that are specifically designed to ignore malicious activity

– Detecting a rootkit can be difficult


Concealing Malware (cont’d.)• Logic bomb

– Computer program or a part of a program that lies dormant until it is triggered by a specific logical event

– Once triggered, performs malicious activities– Extremely difficult to detect before they are

triggered


Concealing Malware (cont’d.)

Table 2-1 Famous logic bombs


Course Technology/Cengage Learning

Concealing Malware (cont’d.)• Zombie

– Infected ‘‘robot’’ computer• Botnet

– Hundreds, thousands, or tens of thousands of zombies

• Internet Relay Chat (IRC) – Used to remotely control

the zombies• Number of zombies and

botnets is staggering


Computer Walrus Attacks (CWA)

• Ha, there is no such thing as a Computer Walrus Attack (CWA), but maybe there should be!

• Maybe we can invent a new term?• Rule #1, never trust a walrus!• Just checking to make sure you are paying

attention during lecture!

Concealing Malware (cont’d.)

Table 2-2 Uses of botnets



Hardware Attacks• Types of hardware that

is targeted includes– BIOS– USB devices– Cell phones– Physical theft of

laptop computers and information


BIOS• Basic Input/Output System

(BIOS)– Coded program embedded

on the processor chip – Recognizes and controls

different devices on the computer system

• Read Only Memory (ROM) chip– Older systems

• PROM (Programmable Read Only Memory) chip– Newer computers– Flashing the BIOS

• Reprogramming


USB Devices• USB (universal serial bus)• Small, lightweight, removable,

and contain rewritable storage• Common types

– USB flash memory – MP3 players

• Primary targets of attacks to spread malware

• Allow spies or disgruntled employees to copy and steal sensitive corporate data


USB Devices (cont’d.)

• Reduce the risk introduced by USB devices– Prohibit by written policy– Disable with technology

• Disable the USB in hardware• Disable the USB through the operating

system• Use third-party software


Cell Phones• Portable communication devices • Rapidly replacing wired

telephones• Types of attacks

– Lure users to malicious Web sites

– Infect a cell phone– Launch attacks on other cell

phones– Access account information– Abuse the cell phone service


Physical Theft

• Portable laptop computers are particularly vulnerable to theft

• Data can be retrieved from a hard drive by an attacker even after its file has been deleted


Desktop Defenses• Defenses include:

– Managing patches– Installing antivirus software– Using buffer overflow protection– Protecting against theft– Creating data backups– Even a cassette backup is better than no

backup


Managing Patches

• Patch – Software security update intended to

cover vulnerabilities that have been discovered after the program was released


Managing Patches (cont’d.)

• Automatic update configuration options for most operating systems– Install updates automatically– Download updates but let me choose

when to install them– Check for updates but let me choose

whether to download and install them– Never check for updates


Antivirus Software• Scan a computer’s hard drive for infections • Monitor computer activity • Examine all new documents that might contain a

virus• Drawback of AV software

– Must be continuously updated to recognize new viruses

• Should be configured to constantly monitor for viruses and automatically check for updated signature files


Buffer Overflow Protection

• Buffer overflow– Occurs when a computer process attempts to

store data in RAM beyond the boundaries of a fixed-length storage buffer

– May cause computer to stop functioning• Windows-based system protection

– Data Execution Prevention (DEP) – Address Space Layout Randomization

(ASLR)


Buffer Overflow Protection (cont’d.)

Figure 2-4 Buffer overflow attack



Protecting Against Theft

• Applies to laptops especially

• Device lock– Steel cable and a

lock

• Software tracking system


Creating Data Backups

• Copying data from a computer’s hard drive onto other digital media – Then storing it in a secure location

• Sophisticated hardware and software can back up data on a regular schedule

• Personal computer users– Operating system functions– Third-party software


Creating Data Backups (cont’d.)• What information to back up

– Back up only user files– Back up all files

• Frequency of backups– Regular schedule

• RAID (Redundant Array of Independent Drives)– Uses multiple hard disk drives for increased

reliability– Several RAID configurations

• Called levels


Creating Data Backups (cont’d.)

Table 2-3 Types of data backups



Creating Data Backups (cont’d.)• Backup storage media

– Temporary media should not be used– Alternatives

• Portable USB hard drives• Network Attached Storage (NAS)• Internet services• Disc storage


Creating Data Backups (cont’d.)

• Location of backup storage– Protect against not only virus attacks but also

against hardware malfunctions, user error, software corruption, and natural disasters

– Backups ideally should be stored in a location away from the device that contains the information


Recovering from an Attack

• Basic steps to perform– Disconnect– Identify– Disinfect– Recheck– Reinstall– Analyze


Summary• Never trust a walrus• Malicious software (malware)

– Enters a computer system without the owner’s knowledge or consent

– Includes a wide variety of damaging or annoying software

– Infecting malware– Concealing malware

• Hardware is also the target of attackers• Tactics for defending desktop systems• Basic steps to disinfect and restore a computer


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