Malicious Software

Chapter 21

MALICIOUS SOFTWARE

o Types Of Malicious Software

·        Backdoor

·        Logic Bomb

·        Trojan Horses

·        Mobile Code

·        Multiple-Threat Malware

o Viruses

·        The Nature of Viruses

·        Viruses Classification

·        Virus Kits

·        Macro Viruses

·        E-Mail Viruses

o Virus Countermeasures

·        Antivirus Approaches

·        Advanced Antivirus Techniques

o Worms

·        The Morris Worm

·        Worm Propagation

·        Model Recent Worm Attacks

·        State of Worm Technology

·        Mobile Phone

·        Worms Worm Countermeasures

o Distributed Denial Of Service  Attacks

·        DDoS Attack Description

·        Constructing the Attack Network

·        DDoS Countermeasures

KEY POINTS

◆      Malicious software is software that is intentionally included or inserted in a system for a harmful purpose.

◆      A virus is a piece of software that can “infect” other programs by modify- ing them; the modification includes a copy of the virus program, which can then go on to infect other programs.

◆      A worm is a program that can replicate itself and send copies from com- puter to computer across network connections. Upon arrival, the worm may be activated to replicate and propagate again. In addition to propaga- tion, the worm usually performs some unwanted function.

◆      A denial of service (DoS) attack is an attempt to prevent legitimate users of a service from using that service.

◆      A distributed denial of service attack is launched from multiple coordinated sources.

Perhaps the most sophisticated types of threats to computer systems are presented by programs that exploit vulnerabilities in computing systems. Such threats are referred to as malicious software, or malware. In this context, we are concerned with threats to application programs as well as utility programs, such as editors and compilers, and kernel-level programs.

This chapter examines malicious software, with a special emphasis on viruses and worms. The chapter begins with a survey of various types of malware, with a more detailed look at the nature of viruses and worms. We then turn to distributed denial-of-service attacks. Throughout, the discussion presents both threats and countermeasures.