Security Principles Haipeng Dai haipengdai@nju.edu.cn 313 CS Building Department of Computer Science and Technology Nanjing University
Security Principles Haipeng Dai haipengdai@nju.edu.cn 313 CS Building Department of Computer Science and Technology Nanjing University
Security Principles Variations of lists of security principles Security vulnerabilities often exploit violations of these principles ■ Good security solutions or countermeasures follow these principles Some overlap some tension between principles More generally,checklists are useful for security These principles can be applied at many levels,e.g.,in source code of an application,between applications on a machine at OS level,at network level,within an organization,between organizations Here we give 16 principles Main Source:software security principles by Gary McGraw and John Viega ■CSE825 2
CSE825 2 Security Principles Variations of lists of security principles Security vulnerabilities often exploit violations of these principles Good security solutions or countermeasures follow these principles Some overlap & some tension between principles More generally, checklists are useful for security These principles can be applied at many levels, e.g., in source code of an application, between applications on a machine at OS level, at network level, within an organization, between organizations Here we give 16 principles Main Source: software security principles by Gary McGraw and John Viega
Principle 1:Securing the weakest Security is a chain;a system is only as secure as the weakest link Spend your efforts on improving the security of the weakest part of a system,as this is where attackers will attack Bank vs.convenience store -Firewall vs.application visible through firewall Social engineering:a common weak link -Software can be weak,surrounding infrastructure can be weaker. -Typical scenario:a service center gets a call from a sincere-sounding user Educating users may be best investment to improve security,eg.,think of phishing attacks,weak passwords Table ll.Character composition information about each password dataset a-zA- Dataset a-z+A-Z+A-Za-z+0-9]+ [a-z+ a-z+1 a-zA-Z+ T0-9]+ T0-9]+ Z0-9]+ [0-9]+ [0-9]+[a-zA-Z]+ [a-z]+ Tianya 9.966 0.18% 10.29% 63.776 98.059% 14.63% 0.12% 15.64% 4.379% 4.11% Dodonew 8.79% 0.27% 9.37% 20.49% 82.88% 40.81% 1.39% 42.94% 7.31% 6.95% CSDN 11.64% 0.47% 12.35% 45.01% 96.31% 26.14% 0.24% 28.45% 6.46% 5.88% Duowan 10.30% 0.09% 10.52%52.84% 97.59% 23.97% 0.37% 24.84% 6.04% 5.83% Myspace 7.18% 0.31% 7.66% 0.71%89.95% 65.66% 18.24% 69.779% 6.02% 5.66% Singles.org 60.20% 1.92% 65.829%6 9.58%99.78% 17.77% 2.73% 19.68% 1.92% 1.77% Faithwriters 54.40% 1.16% 59.04% 6.35% 99.57% 22.82% 4.13% 25.45% 2.73% 2.37% Hak5 18.61% 0.27% 20.39% 5.56%92.13% 16.57% 2.01% 31.80% 1.44% 1.21% -CSE825 3
CSE825 3 Principle 1: Securing the weakest Security is a chain; a system is only as secure as the weakest link. Spend your efforts on improving the security of the weakest part of a system, as this is where attackers will attack. ─ Bank vs. convenience store ─ Firewall vs. application visible through firewall Social engineering: a common weak link. ─ Software can be weak, surrounding infrastructure can be weaker. ─ Typical scenario: a service center gets a call from a sincere-sounding user ─ Educating users may be best investment to improve security, eg., think of phishing attacks, weak passwords
Principle 1:Securing the weakest link Table IV.Top 10 most popular passwords of each dataset Rank Tianya Dodonew CSDN Duowan Myspace Singles.org Faithwriters Hak5 123456 123456 123456789 123456 passwordl 123456 123456 QsEfTh22 2 111111 a123456 12345678 111111 abe123 jesus writer 3 000000 123456789 11111111 123456789 fuckyou password jesusl timosha Top 3(%) 5.58% 1.49% 8.15% 5.01% 0.40% 2.10% 1.03% 4.62% 4 123456789 111111 dearbook 123123 monkey1 12345678 christ ike02banaA 5 123123 5201314 00000000 000000 iloveyoul christ blessed 123456 6 123321 123123 123123123 5201314 myspacel love john316 zxczxc 7 5201314 a321654 1234567890 123321 fuckyoul princess jesuschrist 123456789 8 12345678 12345 88888888 a123456 numberl jesusl password westside 9 666666 000000 111111111 suibian footballl sunshine heaven ZVjmHgC355 10 111222tianya 123456a 147258369 12345678 nicolel 1234567 faithwriters Kj7Gt65F Top10(%) 7.42% 3.28% 10.44% 6.78% 0.78% 3.409% 2.17% 7.20% Credit card example -threats to credit card numbers include: eavesdropping on the network stealing from customer database me loosing my wallet-weakest link Solution:risk analysis. -CSE825 4
CSE825 4 Principle 1: Securing the weakest link Credit card example - threats to credit card numbers include: ● eavesdropping on the network ● stealing from customer database ● me loosing my wallet – weakest link Solution: risk analysis
Principle 2:Defense in depth If one layer fails,hopefully another layer can succeed. No single point of failure. Why is bank more secure than convenience store? -Redundant security measures:security guard,bulletproof glass, electronically locked doors,vault protecting the rest and requiring the presence of two individuals who are rarely at the bank at the same time, security camera,... Well-known principle even beyond security -Have a series of defenses so that if an error isn't caught by one,it will probably be caught by another.(From Bruce MacLennan's Principles of Programming Languages. Securing the weakest link applies to nonoverlapping functions. Defense in depth applies to same function. -CSE825 5
CSE825 5 Principle 2: Defense in depth If one layer fails, hopefully another layer can succeed. No single point of failure. Why is bank more secure than convenience store? ─ Redundant security measures: security guard, bulletproof glass, electronically locked doors, vault protecting the rest and requiring the presence of two individuals who are rarely at the bank at the same time, security camera,… Well-known principle even beyond security ─ Have a series of defenses so that if an error isn't caught by one, it will probably be caught by another. (From Bruce MacLennan's Principles of Programming Languages.) Securing the weakest link applies to nonoverlapping functions. Defense in depth applies to same function