CSC 682: Advanced Computer Security

1. Introduction CSC 682: Advanced Computer Security CSC 682: Advanced Computer Security

2. CSC 682: Advanced Computer Security About Me http://www.nku.edu/~waldenj1 James Walden • Assistant Professor of Computer Science • waldenj@nku.edu • Interests: • Software Security • Programming Languages • Software Engineering • Network Security

3. CSC 682: Advanced Computer Security Course Administration Web Site • Notes, readings, and assignments on web site. • http://www.nku.edu/~waldenj1 Assignment submission • Use submit command on kosh. Contact Information • Email: waldenj@nku.edu • Phone: (859) 572-5571

4. CSC 682: Advanced Computer Security Topics • What is Security? • Web Security • Evaluating Research

5. CSC 682: Advanced Computer Security What is Security? Security is the prevention of certain types of intentional actions from occuring in a system. • These potential actions are threats. • Threats that are carried out are attacks. • Intentional attacks are carried out by an attacker. • Objects of attacks are assets.

6. CSC 682: Advanced Computer Security Safety vs Security Adversary: An intelligent attacker who intentionally causes the system to fail. • Safety • Home: fire alarm. • Car: crumple zones. • Computer: UPS. • Security • Home: door lock. • Car: alarm. • Computer: Login password. Safety and security can interact: Who is watching your computer room after the fire alarm was pulled?

7. CSC 682: Advanced Computer Security Goals of Security Prevention • Prevent attackers from violating security policy Detection • Detect attackers’ violation of security policy Recovery • Stop attack, assess and repair damage Survivability • Continue to function correctly even if attack succeeds

8. CSC 682: Advanced Computer Security NSTISSC Security Model

9. CSC 682: Advanced Computer Security Components of Security Confidentiality • Keeping data and resources hidden. Privacy. Integrity • Preventing unauthorized changes to data or resources. Availability • Enabling access to data and resources

10. CSC 682: Advanced Computer Security Confidentiality Authentication Passwords, mother’s maiden name Corporations Trade secrets, e.g., the formula for Coca Cola. Databases SSN, Driver’s license Governments National security Embarrassing information: www.thememoryhole.org

11. CSC 682: Advanced Computer Security Integrity Data Integrity • content of the information. • ex: 2005 Walmart $1.5 million bar code scam. Origin Integrity (authentication)‏ • source of the information. • ex: 1997 Kurt Vonnegut MIT commencement address email. Vonnegut was not the 1997 speaker and the content wasn’t his. Prevention vs Detection

12. CSC 682: Advanced Computer Security Availability Prevent loss of system access. Denial of service attacks common. • Easy to launch, difficult to track down. • Can be just part of another attack

13. CSC 682: Advanced Computer Security States of Information • Storage Information not currently being accessed. • Processing Information currently being used by processor. • Transmission Information in transit btw one node and another.

14. CSC 682: Advanced Computer Security Security Measures Technology. • Hardware/software used to ensure confidentiality, integrity, or availability. Policy and practice. • Security requirements and activities. Education, training, and awareness. • Understanding of threats and vulnerabilities and how to protect against them.

15. CSC 682: Advanced Computer Security How to evaluate security solutions? • What assets are you trying to protect? • What are the risks to those assets? • How well does the security solution mitigate those risks? • What other risks does the security solution cause? • What costs and trade-offs does the security solution impose?

16. CSC 682: Advanced Computer Security Aspects of Risks To evaluate a risk, we need to evaluate both: • Probability of risk occurring. • Cost incurred by risk if it occurs. Minimize product of probability and cost. Risks are impacted by environment. • Building a house in a flood plain incurs additional risks beyond that of house itself. • Similarly, installion and configuration options impact risk of software systems.

17. CSC 682: Advanced Computer Security Security is a matter of Trade-offs Security is only one of many system goals: • Functionality • Ease of Use • Efficiency • Time to market • Cost • Security

18. CSC 682: Advanced Computer Security Cost-Benefit Analysis Is it cheaper to prevent violation or recover? • Cost of good network security: • Money, time, reduced functionality, annoyed users. • Large and ongoing. • Risks of bad network security: • Angry customers, bad press, network downtime. • Small and temporary.

19. CSC 682: Advanced Computer Security Airport Security Let’s consider the issue of airport security from the standpoint of what we’ve learned. Develop a solution, keeping the 5 questions in mind: • What assets are you trying to protect? • What are the risks to those assets? • How well does the security solution mitigate those risks? • What other risks does the security solution cause? • What costs and trade-offs does the security solution impose?

20. CSC 682: Advanced Computer Security Human Issues: People Problems Social engineering • Kevin Mitnick testified before Congress “I was so successful in that line of attack that I rarely had to resort to a technical attack.” Circumvention • Users write down passwords, leave screens unlocked. Insider attacks

21. CSC 682: Advanced Computer Security Human Issues: Organizations Low priority • Security costs, but doesn’t produce income. • Lack of liability reduces costs of bad security. Variable impact • Cost of security violation highly variable. • Insurance converts variable risk to fixed cost, but risk too variable for much involvement so far. Power and responsibility • Personnel responsible for security often don’t have power to enforce security.

22. CSC 682: Advanced Computer Security Security: Laws and Customs Are desired security measures illegal? • cryptography export before 2000 • is it legal to monitor security breakins? • international commerce Will users circumvent them? • writing down passwords • removing file ACLs

23. CSC 682: Advanced Computer Security Security Liability Product liability: • Tires: Continental recalled Ford SUV tires in 2002 due to wire and vibration problems. • Software: Manufacturer not liable for security flaws. Since Microsoft isn’t liable for Windows security failures, why would they want to sacrifice money, time, functionality, and ease of use for security?

24. CSC 682: Advanced Computer Security Assumptions • Security rests on assumptions specific to type of security required and environment. • Example: • TCP/IP designed for pre-commercial Internet. • Assumed only legitimate admins had root access. • Trusted IP addresses, since only root can set IP addr. • What happens to network when Windows 95 systems added to network, where desktop user has all privileges?

25. CSC 682: Advanced Computer Security Assurance How much can you trust a system? Example: • Purchasing aspirin from a drugstore. • Bases for trust: • Certification of drug by FDA. • Reputation of manufacturer. • Safety seal on bottle.

26. CSC 682: Advanced Computer Security How much do you trust? Ken Thompson’s compiler hack from “Reflections on Trusting Trust.” • Modified C compiler does two things: • If compiling a compiler, inserts the self-replicating code into the executable of the new compiler. • If compiling login, inserts code to allow a backdoor password. • After recompiling and installing old C compiler: • Source code for Trojan horse does not appear anywhere in login or C compiler. • Only method of finding Trojan is analyzing binary.

27. CSC 682: Advanced Computer Security What is web application security? The art and science of developing web applications that function correctly even when under attack.

28. CSC 682: Advanced Computer Security Reasons for Attacking Web Apps

29. CSC 682: Advanced Computer Security A Growing Problem

30. CSC 682: Advanced Computer Security Firewalls don’t protect web apps telnet Firewall ftp Application DatabaseServer WebClient WebServer Application HTTP Traffic Port 80

31. CSC 682: Advanced Computer Security HTTP: HyperText Transfer Protocol Simple request/response protocol • Request methods: GET, POST, HEAD, etc. • Stateless: req#2 doesn’t know about req#1 HTTPS • HTTP wrapped in SSL/TLS encryption • Protects data in transit to web server. • Doesn’t protect stored data. • Doesn’t protect server from being hacked.

32. CSC 682: Advanced Computer Security HTTP Request GET http://www.google.com/ HTTP/1.1 Host: www.google.com User-Agent: Mozilla/5.0 (Windows NT 5.1) Gecko/20060909 Firefox/1.5.0.7 Accept: text/html, image/png, */* Accept-Language: en-us,en;q=0.5 Cookie: rememberme=true; PREF=ID=21039ab4bbc49153:FF=4 Method URL Protocol Version Headers Blank Line No Data for GET

33. CSC 682: Advanced Computer Security HTTP Response HTTP/1.1 200 OK Cache-Control: private Content-Type: text/html Server: GWS/2.1 Date: Fri, 13 Oct 2006 03:16:30 GMT <HTML> ... (page data) ... </HTML> Protocol Version HTTP Response Code Headers Blank Line Web Page Data

34. CSC 682: Advanced Computer Security HTTP GET Parameters http://ex.com/path/app.cgi?param1=val1&param2=val2 Format • parameter_name=value • Multiple parameters separated by & URI encoding • Encode chars as ISO-Latin hex val: %XY • Special characters must be encoded. • Any character may be encoded.

35. CSC 682: Advanced Computer Security HTTP POST Parameters POST /path/app.cgi HTTP/1.0 Content-Type: application/x-www-form-urlencoded Content-Length: 32 param1=value1&param2=value2 Format • parameter_name=value • Multiple parameters separated by & URI encoding

36. CSC 682: Advanced Computer Security Cookies HTTP/1.1 200 OK Content-Type: text/html Set-Cookie: Name=Value; path=/; expires=01-Jan-2038 23:59:59UCT GET /path/app.cgi HTTP/1.1 Host: ex.com Cookie: Name=Value Cookie Format • Only sent to URLs that match path, domain. • Sent only via SSL if secure specified. • Expires on date or when browser closed.

37. CSC 682: Advanced Computer Security Web Application Vulnerabilities Input-based Security Problems • Injection Flaws • Insecure Remote File Inclusion • Unvalidated Input Authentication and Authorization • Authentication • Access Control • Cross-Site Scripting Other Bugs • Error Handling and Information Leakage • Insecure Storage • Insecure Communications

38. CSC 682: Advanced Computer Security Vulnerability Trends for 2006

39. CSC 682: Advanced Computer Security Key Points • Components of security • Confidentiality, Integrity, Availability • States of information • Storage, Processing, Transmission • Security is a matter of trade-offs. • Web Input • HTTP stateless request/response protocol. • Cookies are HTTP headers used to provide state. • SSL protects data in transit, but not in storage.

40. CSC 682: Advanced Computer Security References • Ross Anderson, Security Engineering, Wiley, 2001. • Matt Bishop, Introduction to Computer Security, Addison-Wesley, 2005. • Peter Neumann, (moderator), Risks Digest, http://catless.ncl.ac.uk/Risks/ • Bruce Schneier, Beyond Fear, Copernicus Books, 2003. • Ken Thompson, “Reflections on Trusting Trust”, Communication of the ACM, Vol. 27, No. 8, August 1984, pp. 761-763 (http://www.acm.org/classics/sep95/)‏