The Security Problem Security must consider external environment of the system, and protect it from: unauthorized access. malicious modification or destruction accidental introduction of inconsistency. Easier to protect against accidental than malicious misuse.

Security A system is secure if its resources are used and accessed as intended under all circumstances.

Java Security Model

What is Security? All Security is based on the answers to the questions. Who do you trust? How much do you trust them? The answers to these questions form a Security Policy

What is System Security? Computer Security commonly refers to the mechanisms available to enforce the Security Policy

Security Components Physical Security

Obviously, if your computer is stolen, you have no security Physical Security Obviously, if your computer is stolen, you have no security

Physical Security WiFi – defined network Bluetooth– ad-hoc network

Security Components Physical Security Authentication

Authentication Verify that someone is who they say they are Two general methods Data item you know (e.g. password) Data media you have (e.g. card)

Authentication Problems with Passwords User selects System selects Dictionary Attack System selects May not be easily guessed, but… User can’t remember it and… Writes it on a post-it note

Authentication Problems with data media you have Can be lost or stolen Can be forged

Authentication Combination of both Examples ATM card requires a PIN SecurID card requires PIN

Authentication Biometrics Data item you have that most likely cannot be lost or stolen Examples Fingerprint Retinal Scan Facial Recognition Voice Recognition

Security Components Physical Security Authentication Protection

Protection Mechanisms to control what an authenticated user can do. File Protection Memory Protection Web Protection

Protection Mechanism to keep unauthorized users from accessing the system Firewalls Virus Detection Spyware Detection

Security Components Physical Security Authentication Protection Encryption

Encryption Scrambles data so that eavesdroppers cannot read what is being transmitted Also used as part of Authentication to help ensure that someone is not posing as somebody else

Security Components Physical Security Authentication Protection Encryption People

People Lack of knowledge about security People will not keep data secure. People can be conned into giving out information they shouldn’t Poor System Administration

Types of Attacks Trojan Horse Trap Door Stack & Buffer Overflow Worm Virus Denial of Service

Trojan Horse Program that appears to be a legitimate agent or process but really behaves in a different manner Viruses and Spyware are often introduced as Trojan Horses

Trap Door A way to bypass the normal security protections Often left in applications / systems to help support staff

Stack & Buffer Overflow Send an incorrectly formatted command / message to a system. If system does not carry out adequate checking, it may execute some action it shouldn’t

Stack & Buffer Overflow How does this happen? Poorly Programmed Read Should be read(file,buffer,100) Instead of read(file,buffer) which reads as much data as the remote system sends Inadequate checking of the validity of the data that is received

Stack & Buffer Overflow Security Design Rule Assume any data you receive is incorrectly formatted (Until proven otherwise)

SQL Injection Application does inadequate validation of user input before putting it into an SQL statement Example SELECT BALANCE FROM ACCTS WHERE ACCT_ID=xxxx User Input for xxxx 104;UPDATE ACCTS SET BALANCE=100000 WHERE ACCT_ID=104

Worm A program that automatically sends itself to another system

Virus Program that attacks a system to carry out some action the computer user does not want

Denial of Service Typical attack sends so many messages to a system, that system cannot execute anything except respond to those messages

Modern Attacks A modern attack will often employ several combinations of these attacks

Example Attack I Kournikova Virus Enticed people to open an email attachment Attachment was a virus that used mail program’s address book to propagate itself

Example Attack II Windows XP Universal Plug n Play Upnp is a feature of Win XP that is intended to allow people to control their (future) internet connected home appliances from any computer Early Flaw: Buffer Overflow problem

Example Attack II Windows XP Universal Plug n Play XP was touted as MS’s most secure OS Reality: ALL XP systems were vulnerable to be hacked

Example Attack III Wireless LAN Laptop Office Network

Example Attack III IEEE 802.11 Wireless LAN Marketed as having Wired Equivalent Privacy Uses Encryption to keep data private Flaw: Bad Encryption Result: one can monitor traffic for about a day and then easily break into the network Several apps available on web for executing this hack

Example Attack IV

Example Attack IV Distributed Denial of Service Attack Hacker compromised several computers Programmed each of those systems to repeatedly send messages to “target” Hacker shutdown many popular websites

Problem Set The following topics are also important Types of attacks Virtual Memory 8/9/2018 Problem Set The following topics are also important Types of attacks Protection policies and mechanisms Encryption, digital signature, PKI, digital certificate Authentication What are the advantages of encrypting data stored in the computer system? Compare symmetric and asymmetric encryption schemes, and discuss under what circumstances a distributed system would use one or the other. J Garrido

Virtual Memory 8/9/2018 Problem Set Discuss how the asymmetric encryption algorithm can be used to achieve the following goals. Authentication: the receiver knows that only the sender could have generated the message Secrecy: only the receiver can decrypt the message Authentication and Secrecy: only the receiver can decrypt the message, and the receiver knows that only the sender could have generated the message J Garrido