上海交通大学：操作系统安全（PPT课件讲稿）操作系统安全 OS Security（邹恒明）

★ ★★ Chapter 7: OS Security ★★ Instructor: Hengming Zou, Ph.D. CLACKs n Pursuit of Absolute simplici求于至筍,归于永恒二

1 Chapter 7: OS Security Instructor: Hengming Zou, Ph.D. In Pursuit of Absolute Simplicity求于至简，归于永恒

斗 长 Content ￥斗 ★★ o The securityenvironment o Basics of cryptography o User authentication s Intrusions and attacks o Protection mechanisms o Trusted systems

2 Content  The security environment  Basics of cryptography  User authentication  Intrusions and attacks  Protection mechanisms  Trusted systems

斗 长 Hardware Reality ￥斗 ★★ o Collection of processor, memory, disks, network interfaces that can be used by anyone to do anything o Or could tum it off, leaving you with hardware thatwon't do anything for anyone

3 Hardware Reality  Collection of processor, memory, disks, network interfaces that can be used by anyone to do anything  Or could turn it off, leaving you with hardware that won’t do anything for anyone

斗 长 Security Goals and Threats ￥斗 ★★ Goal Threat Data Confidentiali Exposure of data Data Integrity Tampering with data Personal Privacy Misuse of data System Availability Denial of service Acts of god

4 Security Goals and Threats Goal Threat Data Confidentiality Exposure of data Data Integrity Tampering with data Personal Privacy Misuse of data System Availability Denial of service Acts of God

斗 长 Security Threats ￥斗 ★★ s Natural or man-made disasters fires, floods, earthquake, wars o Hardware or software errors CPU malfunction, bad disk program bugs s Human errors dataentry, wrong tape mounted o Attacks by intruders or adversaries This is where we will focus in this lecture

5 Security Threats  Natural or man-made disasters – fires, floods, earthquake, wars  Hardware or software errors – CPU malfunction, bad disk, program bugs  Human errors – data entry, wrong tape mounted  Attacks by intruders or adversaries – This is where we will focus in this lecture

斗 长 Intrusion motive ￥斗 ★★ o Casual prying by non-technical users o Snooping by insiders o Determined attemptto make money o Commercial or militaryespionage

6 Intrusion Motive  Casual prying by non-technical users  Snooping by insiders  Determined attempt to make money  Commercial or military espionage

斗 长 Some Example Attacks ￥斗 ★★ o Spoof identity pretend to send a message from your IP address s Man-in-the-middle attack Eavesdrop and delete the original message Insert new message that pretends to be from original sender Replayold messages

7 Some Example Attacks  Spoof identity – pretend to send a message from your IP address  Man-in-the-middle attack – Eavesdrop and delete the original message – Insert new message that pretends to be from original sender – Replay old messages

斗 长 Security Elements ￥斗 ★★ o Data security not viewed by unauthorized personnel data are not tampered o System security Systems do not do things not supposed to do

8 Security Elements  Data security – not viewed by unauthorized personnel – data are not tampered  System security – Systems do not do things not supposed to do

斗 长 Security Elements ￥斗 ★★ o Static security Data stored are not compromised Achieved by access control and cryptography o Dynamic security Data in transit is not compromised Achieved by secure communication

9 Security Elements  Static security – Data stored are not compromised – Achieved by access control and cryptography  Dynamic security – Data in transit is not compromised – Achieved by secure communication

斗 长 Secure communication ￥斗 ★★ o Confidentiali Attacker should not be able to understand data ≈ Authentication: Assure receiver that message is from the right sender s Freshness. Attacker should not be able to replay an old request o Availability No denial-of-service

10 Secure Communication  Confidentiality: – Attacker should not be able to understand data  Authentication: – Assure receiver that message is from the right sender  Freshness: – Attacker should not be able to replay an old request  Availability: – No denial-of-service