Ch15 - Chapter 15 Security Silberschatz Galvin and Gagne 2009 Chapter 15 Security s The Security Problem s Program Threats s System and Network

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Silberschatz, Galvin and Gagne ©2009 Chapter 15: Security
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15.2 Silberschatz, Galvin and Gagne ©2009 Chapter 15: Security The Security Problem Program Threats System and Network Threats Cryptography as a Security Tool User Authentication Implementing Security Defenses Firewalling to Protect Systems and Networks Computer-Security Classifications An Example: Windows XP
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15.3 Silberschatz, Galvin and Gagne ©2009 Objectives To discuss security threats and attacks To explain the fundamentals of encryption, authentication, and hashing To examine the uses of cryptography in computing To describe the various countermeasures to security attacks
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15.4 Silberschatz, Galvin and Gagne ©2009 The Security Problem Security must consider external environment of the system, and protect the system resources Intruders (crackers) attempt to breach security Threat is potential security violation Attack is attempt to breach security Attack can be accidental or malicious Easier to protect against accidental than malicious misuse
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15.5 Silberschatz, Galvin and Gagne ©2009 Security Violations Categories Breach of confidentiality Breach of integrity Breach of availability Theft of service Denial of service Methods Masquerading (breach authentication) Replay attack Message modification Man-in-the-middle attack Session hijacking
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15.6 Silberschatz, Galvin and Gagne ©2009 Standard Security Attacks
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15.7 Silberschatz, Galvin and Gagne ©2009 Security Measure Levels Security must occur at four levels to be effective: Physical Human Avoid social engineering, phishing, dumpster diving Operating System Network Security is as week as the weakest chain
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15.8 Silberschatz, Galvin and Gagne ©2009 Program Threats Trojan Horse Code segment that misuses its environment Exploits mechanisms for allowing programs written by users to be executed by other users Spyware, pop-up browser windows, covert channels Trap Door Specific user identifier or password that circumvents normal security procedures Could be included in a compiler Logic Bomb Program that initiates a security incident under certain circumstances Stack and Buffer Overflow Exploits a bug in a program (overflow either the stack or memory buffers)
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15.9 Silberschatz, Galvin and Gagne ©2009 C Program with Buffer-overflow Condition #include < stdio.h > #define BUFFER SIZE 256 int main(int argc, char *argv[]) { char buffer[BUFFER SIZE]; if (argc < 2) return -1; else { strcpy(buffer,argv[1]); return 0; } }
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15.10 Silberschatz, Galvin and Gagne ©2009 Layout of Typical Stack Frame
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15.11 Silberschatz, Galvin and Gagne ©2009 Modified Shell Code #include <stdio.h> int main(int argc, char *argv[]) { execvp(‘‘\bin\sh’’,‘‘\bin \sh’’, NULL); return 0; }
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15.12 Silberschatz, Galvin and Gagne ©2009 Hypothetical Stack Frame Before attack After attack
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15.13
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This note was uploaded on 07/13/2011 for the course COP 4610 taught by Professor Staff during the Summer '08 term at FAU.

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Ch15 - Chapter 15 Security Silberschatz Galvin and Gagne 2009 Chapter 15 Security s The Security Problem s Program Threats s System and Network

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