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Operating System Security & Smartphones MD SHAHREAR IQBAL PHD STUDENT QRST LAB, SCHOOL OF COMPUTING QUEEN’S UNIVERSITY, KINGSTON, ONTARIO, CANADA. 2 CISC 324: Security & Protection Concepts Protection: Mechanisms and policy to keep programs and users from accessing or changing stuff they should not do Internal to OS Chapter 14 in Silbershatz Security: Issues external to OS Authentication of user, validation of messages, malicious or accidental introduction of flaws, etc. Chapter 15 of Silbershatz 3 Goals of Protection In one protection model, computer consists of a collection of objects, hardware or software Each object has a unique name and can be accessed through a welldefined set of operations Protection problem - ensure that each object is accessed correctly and only by those processes that are allowed to do so Slides from Operating System Concepts – 9th Edition, Silberschatz, Galvin, Gagne 4 Principles of Protection 5 Guiding principle – principle of least privilege Programs, users and systems should be given just enough privileges to perform their tasks Limits damage if entity has a bug, gets abused Can be static (during life of system, during life of process) Or dynamic (changed by process as needed) – domain switching, privilege escalation “Need to know” a similar concept regarding access to data Slides from Operating System Concepts – 9th Edition, Silberschatz, Galvin, Gagne Principles of Protection (Cont.) Must consider “grain” aspect Rough-grained privilege management easier, simpler, but least privilege now done in large chunks For example, traditional Unix processes either have abilities of the associated user, or of root Fine-grained management more complex, more overhead, but more protective 6 File ACL lists, RBAC Domain can be user, process, procedure Slides from Operating System Concepts – 9th Edition, Silberschatz, Galvin, Gagne The Security Problem 7 System secure if resources used and accessed as intended under all circumstances Unachievable 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 Slides from Operating System Concepts – 9th Edition, Silberschatz, Galvin, Gagne Security Violation Categories Breach of confidentiality Breach of integrity Unauthorized destruction of data Theft of service Unauthorized modification of data Breach of availability Unauthorized reading of data Unauthorized use of resources Denial of service (DOS) Prevention of legitimate use Slides from Operating System Concepts – 9th Edition, Silberschatz, Galvin, Gagne 8 Security Measure Levels Impossible to have absolute security, but make cost to perpetrator sufficiently high to deter most intruders Security must occur at four levels to be effective: Physical Human Avoid social engineering, phishing, dumpster diving Operating System Data centers, servers, connected terminals Protection mechanisms, debugging Network Intercepted communications, interruption, DOS Security is as weak as the weakest link in the chain But can too much security be a problem? Slides from Operating System Concepts – 9th Edition, Silberschatz, Galvin, Gagne 9 Program Threats Many variations, many names 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 Up to 80% of spam delivered by spyware-infected systems Trap Door Specific user identifier or password that circumvents normal security procedures Could be included in a compiler How to detect them? Slides from Operating System Concepts – 9th Edition, Silberschatz, Galvin, Gagne 10 Program Threats (Cont.) 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) Failure to check bounds on inputs, arguments Write past arguments on the stack into the return address on stack When routine returns from call, returns to hacked address Pointed to code loaded onto stack that executes malicious code Unauthorized user or privilege escalation Slides from Operating System Concepts – 9th Edition, Silberschatz, Galvin, Gagne 11 12 Smartphone Security Security Risks Asset 13 Security Risks Asset 14 Threat Malware Hacker Security Risks Asset Threat Vulnerability Risk malware 15 Vulnerable Operating Systems Vulnerable Apps New Technologies Existing Security for fighting Malware 16 Smart City 17 Clean & nonmotorized options Smart City Smartphone 18 Smart Phone Maintaining separate execution profiles Smart Country Smart Security Framework Implementation View 19 Applications Restricted Zone App 6 App 8 New App Zone App 1 Trusted App Zone App 2 Untrusted App Zone App 5 App 3 App 7 App 4 High Privilege App Zone Zone and Policy Manager App Market Application framework K Secure Communication Application Status and Relationship Management Context Management Trusted Device Management Computation Offloading Management Security Mode Management Data Safety Management Hardware OS Package Installer Permission Checker High Privilege App Service Provider Sensors API Management Custom Telephony/SMS App Behavior Communication Channels Policy Management Zone Management Surveillance K 20 Job & Grad Life Questions 21
