CIT 380: Securing Computer Systems Security Solutions

Threat: Your Adversaries Youthful attackers Organized crime Terrorists Governments The competition Hacktivists Hired guns

Threat: Your Adversaries Disgruntled employees Clueless employees Customers Suppliers Vendors Business partners Contracts, temps, consultants

Threat Perspective “However, just as you don’t want to underestimate the threats that you face, neither do you want to overestimate them.” Counter Hack Reloaded page 10

Threat Assessment “You must sit down and carefully evaluate which threats would be motivated to go after your organization, tally the tangible and intangible value of the assets you have to protect, and then deploy security commensurate with the threat and the value of your systems and information.” Counter Hack Reloaded page 11

CIT 380: Securing Computer Systems Slide #6 How to evaluate security solutions? 1.What assets are you trying to protect? 2.What are the risks to those assets? 3.How well does the security solution mitigate those risks? 4.What other risks does the security solution cause? 5.What costs and trade-offs does the security solution impose?

CIT 380: Securing Computer Systems Slide #7 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.

Aspects of Risks Risks are impacted by environment. – Building a house in a flood plain incurs additional risks beyond that of house itself. – Similarly, installation and configuration options impact risk of software systems. CIT 380: Securing Computer Systems Slide #8

CIT 380: Securing Computer Systems Slide #9 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

CIT 380: Securing Computer Systems Slide #10 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.

CIT 380: Securing Computer Systems Slide #11 Airport Security Let’s consider the issue of airport security again from the standpoint of what we’ve learned. Develop a solution, keeping the 5 questions in mind:

Airport Security 1.What assets are you trying to protect? 2.What are the risks to those assets? 3.How well does the security solution mitigate those risks? 4.What other risks does the security solution cause? 5.What costs and trade-offs does the security solution impose? CIT 380: Securing Computer Systems Slide #12

CIT 380: Securing Computer Systems Slide #13 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

CIT 380: Securing Computer Systems Slide #14 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.

Human Issues: Organizations Power and responsibility – Personnel responsible for security often don’t have power to enforce security. CIT 380: Securing Computer Systems Slide #15

CIT 380: Securing Computer Systems Slide #16 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

CIT 380: Securing Computer Systems Slide #17 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?

CIT 380: Securing Computer Systems Slide #18 Assumptions Security rests on assumptions specific to type of security required and environment.

Assumptions Example: – TCP/IP designed for pre-commercial Internet. Assumed only legitimate administrators had root access. Trusted IP addresses, since only root can set IP address. What happens to network when Windows 95 systems added to network, where desktop user has all privileges? CIT 380: Securing Computer Systems Slide #19

CIT 380: Securing Computer Systems Slide #20 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.

CIT 380: Securing Computer Systems Slide #21 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.

How much do you trust? – 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. CIT 380: Securing Computer Systems Slide #22

CIT 380: Securing Computer Systems Slide #23 Key Points Components of security – Confidentiality – Integrity – Availability States of information – Storage, Processing, Transmission Evaluating risk and security solutions. – Security is a matter of trade-offs. Security is a human problem.

Discussion: Gas Drive Away Without Paying What measures can be imposed? What are the costs for the merchant and the customer? Do the benefits outweigh the costs?

CIT 380: Securing Computer Systems Slide #25 References 1.Ross Anderson, Security Engineering, Wiley, Matt Bishop, Introduction to Computer Security, Addison-Wesley, Peter Neumann, (moderator), Risks Digest, 4.Bruce Schneier, Beyond Fear, Copernicus Books, Ken Thompson, “Reflections on Trusting Trust”, Communication of the ACM, Vol. 27, No. 8, August 1984, pp (