Chapter Nine Maintaining a Computer Part III: Malware

© Wiley, Inc. All Rights Reserved. Strata Objectives Covered 4.1 (3.1 FC0-U11 U.K.) Recognize the basic security risks and procedures to prevent them –Identify risks –Identify prevention methods 4.2 (3.2 FC0-U11 U.K.) Recognize security breaches and ways to resolve them –Recognize the proper diagnostic procedures when infected with a virus –Recognize the proper procedures to maintain a secure environment 2

© Wiley, Inc. All Rights Reserved. Types of Malware Attacks Exploits Viruses Worms Trojan Horses Adware Spyware Rootkits Backdoors Botnets 3

© Wiley, Inc. All Rights Reserved. OS and Application Exploits Vulnerability: a flaw in programming that creates the potential for misuse Exploit: a criminal activity that uses a vulnerability to attack a system All Oses have weaknesses that can be exploited Download and install all available updates and patches to minimize the risk 4

© Wiley, Inc. All Rights Reserved. Viruses A computer code that inserts itself into an executable file When file executes, virus’s code executes too Viruses can have harmless or harmful results Most have a self-replicating component that causes them to spread between executable files via RAM 5

© Wiley, Inc. All Rights Reserved. Trojan Horses Rogue applications that may appear to do something useful but also secretly do something harmful, such as install a keylogger Keylogger records all keystrokes and sends the information to a file or a remote location Trojan horses don’t replicate themselves; they commonly spread via worms 6

© Wiley, Inc. All Rights Reserved. Worms Self-transporting applications that carry an active payload, such as virus or Trojan horse Active or passive –Active: self-transport without human intervention –Passive: rely on user’s innocence to transport themselves, via or social engineering 7

© Wiley, Inc. All Rights Reserved. Adware Application that displays un-asked- for ads; most often comes from an add-on toolbar for the web browser Adware companies make money when people click the ads they display Not all adware is illegal, but it is annoying Adware programs may be difficult to remove, much like a virus infection 8

© Wiley, Inc. All Rights Reserved. Spyware Software that secretly records your computer usage Spyware makers get revenue from collecting consumer marketing data or stealing passwords for criminal activity Most spyware is illegal, and can be difficult to remove Not self-replicating; relies on social engineering to spread 9

© Wiley, Inc. All Rights Reserved. Anti-Malware Software Antivirus software –Defends against viruses, worms, and Trojan horses Anti-spyware software –Defends against adware and spyware Anti-spam software –Reduces the amount of junk you receive Suites combine multiple security functions 10

© Wiley, Inc. All Rights Reserved. Antivirus Software Identifies infections by scanning all files on your hard disk Looks for virus signatures in executable code Maintains a database of virus definitions for which to scan executable files 11

© Wiley, Inc. All Rights Reserved. Antivirus Software May also create MD5 for each application –A math calculation that results in a unique value for the file –If the file’s MD5 doesn’t match its original MD5 value, it may have been altered by a virus Windows Security Essentials is a free antivirus program available from Microsoft 12

© Wiley, Inc. All Rights Reserved. Antivirus Software Usually resident, meaning continuously running in the background Each file is checked as it is opened, and each as it is received Quarantining a file places it in an off-limits area where it can’t be run 13

© Wiley, Inc. All Rights Reserved. Anti-Spyware Software Find and remove adware and spyware Find and remove tracking cookies and other potential privacy threats Many antivirus programs also have anti-spyware capabilities Windows Defender comes free with Windows 14

© Wiley, Inc. All Rights Reserved. Anti-spam Software Spam is unwanted junk mail Most spam tries to sell products or services, or to use social engineering to commit crimes Mail applications often include basic anti-spam capabilities Third-party anti-spam programs are also available 15

© Wiley, Inc. All Rights Reserved. Diagnosing and Fixing Malware Infections Symptoms of infection: –Antivirus software disabled and can’t be re-enabled –System runs sluggishly –CPU and memory usage high –Warning or message boxes refuse to go away –Friends receive strange s from you that you didn’t send –Bombarded with pop-up ads when using web browser 16

© Wiley, Inc. All Rights Reserved. Virus Removal Run a full antivirus check If your antivirus software won’t run, use an online checker such as Follow virus checker advice 17