Security

1
Security

• Davis Rajkumar, pp. 116, 117, 292, 465-474, 516

2
Overview

• Security as effectiveness criterion
• Security implications of kernel privileges
• Client/server environment
• Security
• Hackers and malware
• Vulnerabilities
• Antivirus software
• Firewalls
• Encryption
• Secure sockets layer
• Security services
• TCP Wrappers

3
Security as Effectiveness Criterion

• Security is important criteria for computer
  effectiveness
• As effective criterion, security measures ability
  of system avoid breaches
• Difficult to measure quantitatively

4
Security and Kernel Privileges

• Both Windows NT (and higher) and Unix varieties
  distinguish between users and the kernel
• Windows XP has user mode and kernel mode
• Unix has root and variety of other users
• Kernel (or root)
• All powerful user
• Can bypass security measures

5
Client/Server Environment

• Server
• Computer that provides services
• Client
• Computer or device that receives services

6
Security

• Definition freedom from danger
• System dangers
• Espionage or sabotage
• Crime
• Attack
• Unauthorized use

7
Security Objectives

• Accessensure that authorized user have
  reasonable access to resources need to do work
• Authenticationverify access is authorized
• Integrityensure soundness of software, data, and
  transmissions
• Privacyensure only authorized access of data and
  transmissions
• Non-repudiationoriginator of data or message is
  genuine
• Recoverycapability to get system back online
  following security breach
• Auditabilityensure that security procedures can
  be inspected and evaluated

8
Hackers and Malware

• Hacker troublemakers, spies, terrorists,
  opportunists lacking respect for others
• Malware malicious software
• Viruses
• Boot sector
• File infection
• Macro
• Network
• Trojan horse
• Worm
• Bot

9
Vulnerabilities

• Vulnerability is condition that would allow
  hacker to gain access or do damage
• Exploit is use of vulnerability to breach system
  security
• Known vulnerabilities
• Buffer overflow checks in daemons such as
  Sendmail and IIS
• Default user accounts
• Misconfigured email, ftp and web servers
• Discovery of open ports and host OS discovery
• Denial of service discovery
• Backdoors and virus infected host
• P2P, chat and suspicious file sharing services

10
Antivirus Software

• Software used to detect and remove or disable
  malware
• Signature scanning
• Integrity checking
• Monitoring of unexpected file changes
• Regular updates and modifications
• Consistently report only valid viruses
• Heuristic scanning -- most fallible

11
Firewall
12
DMZ and Firewall
13
Security Technologies

• Encryption
• Concealing content through manipulation of data
• Secret-key cryptography
• Public-key cryptography
• Secure Sockets Layer (SSL)
• Encryption of http transmissions
• Security Services intrusion detection
• TCP Wrappers Unix demon for TCP/IP

14
Summary

• Client/server environment
• Security definition
• Hackers and malware
• Vulnerabilities
• Antivirus software
• Firewalls
• Encryption