Cyber-Security Mini-Course for Middle and High School Students

1. JerseySTEM Mini-course in Cyber-SecurityCourse designed by Prof. Vinod Ganapathy, Rutgers University Slide #1-1

2. About this course: Audience Intended audience: • Late-stage middle-school and early-stage high-school students (7th-10th graders) • Pre-requisites: • Some programming experience, in any language of your choice. • Rudimentary knowledge should suffice, but you should be willing to learn. • Some exposure to the UNIX shell. • Willingness to learn new languages and concepts! Slide #1-2

3. About this course: Contents What you will learn: • Basic cyber-security concepts. • Some black-hat hacking skills (how to attack). • Some white-hat hacking skills (how to defend). • The course will be a mix of theory and hands-on practice. The theory will teach you the concepts and the hands-on exercises will reinforce the theoretical concepts. Slide #1-3

4. About this course: A warning Why teach both black-hat and white-hat skills? • Because you’ve to “know thy enemy” • To effectively defend, you have to know how attackers think • This does not give you the license to show off your black-hat hacking skills. • You can get into deep trouble with law-enforcement if you do so. Consider yourself warned! Slide #1-4

5. Computer security is the study of … • Weaknesses in systems and attacks against them. • Defending against such attacks • Pro-actively protecting data against various attacker models Slide #1-5

6. Goals of computer security • Think of what you would want from your “ideal” anti-virus: • Prevent your files from getting corrupted. • Prevent your identity/credit-card number from being stolen • Avoid giving your password to phishing websites • … (many more examples) Slide #1-6

7. Goals of computer security • We can abstract the goals into a convenient acronym: C.I.A. • Confidentiality • Keeping data and resources hidden from attacker • Integrity • Protecting data from unauthorized modification by attackers • Availability • Enabling legitimate access to data and resources

8. A “secure system” • Is a computer that is connected to the Internet an example of a secure machine? • Can you protect Confidentiality, Integrity and Availability of data on such a machine? • Let’s look at these in turn. Slide #1-8

9. A “secure system” • Is a computer that is connected to the Internet an example of a secure machine? • Protecting Confidentiality: • We routinely read of malicious software and attacks that steal credit card numbers, steal identity, steal passwords, etc. • These attacks violate data confidentiality. Slide #1-9

10. A “secure system” • Is a computer that is connected to the Internet an example of a secure machine? • Protecting Integrity: • Think of ransomware: What does it do? It encrypts your files and prevents you from accessing the data in the files. • These attacks violate data integrity. Slide #1-10

11. A “secure system” • Is a computer that is connected to the Internet an example of a secure machine? • Protecting Availability: • Denial of service (DOS) attacks routinely prevent you from accessing websites. • Recent example: Mirai botnet DOSed Dyn (October 2016) • Violated data availability. Slide #1-11

12. A “secure system” • Let us disconnect the computer from the Internet. Sacrifices some data availability but maybe we’re willing to live with that. • Does it protect data confidentiality? • No! You can still exfiltrate data out of the machine (think USB sticks!) • Does it protect data integrity? • No! You can still infect the machine with malicious software (again, think USB sticks). .

13. A “secure system” • Now, let us disconnect the computer from the Internet, and switch it off! Is it “secure”? • No! Data that is stored on hard disks can still be recovered by bad guys using forensic tools. • There are other kinds of sophisticated attacks too: • Exercise: Google “Cold Boot Attack” and read the associated Wikipedia article

14. So, what is a “secure system”? • The answer to that question is “it depends.” • If you assume a very powerful adversary, you will need very powerful defences to achieve even basic confidentiality and integrity. • What you assume about the adversary (i.e., attacker) is called the threat model .

15. Threat Models in practice • Network-based (or remote) attacker: • Is located remotely, and connected to the victim’s machine via a network link. • Can send and receive packets to the victim’s machine. • This is the threat model that is most used in practice. • For most of this course, we will work with this threat model. Slide #1-15

16. Threat Models in practice • Local attacker: • Has an account to log into the victim’s machine. • Perhaps even has physical access to the machine itself. • Example: Snowden attacks? Other insider attacks. • Makes several restricting assumptions about the adversary, so we won’t use it in the course. Slide #1-16

17. Course plan • We will start with an overview of the working environment: • Basics of UNIX shell, compiling programs, and command-line tools. • Simple C programs and their assembly-language programs. • Learning to read assembly code. • Learning to execute and inspect code within a debugger (gdb) Slide #1-17

18. Course plan • Next up will be on buffer overflows, a major cybersecurity threat: • You will learn the low-level details of how this threat works. • You will be designing exploits and work through an “obstacle course” [Each exploit harder than the previous one!] Slide #1-18

19. Course plan • If you learn how to attack, you should also learn how to defend! • We will study various popular deployed buffer overflow defences and learn how you can apply them. • Often tested in competitions like Cyber Patriot! Slide #1-19

20. Introduction to the UNIX shell and command line, compilers and debuggers

21. Using the UNIX shell • This will be an interactive introduction to using the UNIX shell. • You have each been given a virtual machine with the Ubuntu Linux distribution installed • Click on the Ubuntu VM to launch it. After booting up, it will show a login screen. Type the login name root and use the password root.

22. Using the UNIX shell • Congratulations! You are on the UNIX shell. • You can now try each one of these commands in the virtual machine as you learn about them on the slides. • This virtual machine will be the environment you use for the rest of the course.

23. Contents • Shell Intro • Command Format • Shell I/O • Command I/O • Command Overview • Some content on UNIX shell commands borrowed from material originally created by S. Mokhov, Concordia Univ

24. Shell Intro • A system program that allows a user to execute: • shell functions (internal commands) • other programs (external commands) • shell scripts • Linux/UNIX has a bunch of them, the most common are • tcsh, an expanded version of csh (Bill Joy, Berkley, Sun) • bash, one of the most popular and rich in functionality shells, an expansion of sh (AT&T Bell Labs). Your VM uses the bash shell • ksh, Korn Shell • ...

25. Command Format • Format: command name and 0 or more arguments:% commandname [arg1] ... [argN] • By % sign I mean prompt here and hereafter. • Arguments can be • options (switches to the command to indicate a mode of operation) ; usually prefixed with a hyphen (-) or two (--) in GNU style • non-options, or operands, basically the data to work with (actual data, or a file name)

26. Shell I/O • Shell is a “power-user” interface, so the user interacts with the shell by typing in the commands. • The shell interprets the commands, that may produce some results, they go back to the user and the control is given back to the user when a command completes (in general). • In the case of external commands, shell executes actual programs that may call functions of the OS kernel. • These system commands are often wrapped around a so-called system calls, to ask the kernel to perform an operation (usually privileged) on your behalf.

27. Command I/O • Input to shell: • Command name and arguments typed by the user • Input to a command: • Keyboard, file, or other commands • Standard input: keyboard. • Standard output: screen. • These STDIN and STDOUT are often together referred to as a terminal. • Both standard input and standard output can be redirected from/to a file or other command. • File redirection: • < input • > output • >> output append

28. Commands As you see each command, try it out on the virtual machine.

29. man • Manual Pages • The first command to remember • Contains info about almost everything :-) • other commands • system calls • c/library functions • other utils, applications, configuration files • To read about man itself type:% man man • NOTE: unfortunately there’s no% man woman ...

30. which • Displays a path name of a command. • Searches a path environmental variable for the command and displays the absolute path. • To find which tcsh and bash are actually in use, type:% which tcsh% which bash • % man which for more details

31. chsh • Change Login Shell • Login shell is the shell that interprets commands after you logged in by default. • You can change it with chsh (provided that your system admin allowed you to do so). • To list all possible shells, depending on implementation:% chsh -l% cat /etc/shells • % chsh with no arguments will prompt you for the shell.

32. whereis • Display all locations of a command (or some other binary, man page, or a source file). • Searchers all directories to find commands that match whereis’ argument • % whereis tcsh

33. passwd • Change your login password. • A very good idea after you got a new one. • It’s usually a paranoid program asking your password to have at least 6 chars in the password, at least two alphabetical and one numerical characters. Some other restrictions (e.g. dictionary words or previous password similarity) may apply. • Depending on a privilege, one can change user’s and group passwords as well as real name, login shell, etc. • % man passwd

34. date • Guess what :-) • Displays dates in various formats • % date • % date -u • in GMT • % man date

35. Calendar for month entire year Years range: 1 - 9999 No year 0 Calendar was corrected in 1752 - removed 11 days % cal current month % cal 2 2000 Feb 2000, leap year % cal 2 2100 not a leap year % cal 2 2400 leap year % cal 9 1752 11 days skipped % cal 0 error % cal 2002 whole year cal

36. clear • Clears the screen • There’s an alias for it: Ctrl+L • Example sequence: • % cal • % clear • % cal • Ctrl+L

37. sleep • “Sleeping” is doing nothing for some time. • Usually used for delays in shell scripts. • % sleep 2 2 seconds pause

38. Command Grouping • Semicolon: “;” • Often grouping acts as if it were a single command, so an output of different commands can be redirected to a file: • % (date; cal; date) > out.txt

39. alias • Defined a new name for a command • % alias • with no arguments lists currently active aliases • % alias newcommand oldcommand • defines a newcommand • % alias cl cal 2003 • % cl

40. unalias • Removes alias • Requires an argument. • % unalias cl

41. Display a history of recently used commands % history all commands in the history % history 10 last 10 % history -r 10 reverse order % !! repeat last command % !n repeat command n in the history % !-1 repeat last command = !! % !-2 repeat second last command % !ca repeat last command that begins with ‘ca’ history

42. exit / logout • Exit from your login session. • % exit • % logout

43. shutdown • Causes system to shutdown or reboot cleanly. • May require superuser privileges • % shutdown -h now - stop • % shutdown -r now - reboot

44. List directory contents Has whole bunch of options, see man ls for details. % ls all files except those starting with a “.” % ls -a all % ls -A all without “.” and “..” % ls -F append “/” to dirs and “*” to executables % ls -l long format % ls -al % ls -lt sort by modification time (latest - earliest) % ls -ltr reverse ls

45. cat • Display and concatenate files. • % cat • Will read from STDIN and print to STDOT every line you enter. • % cat file1 [file2] ... • Will concatenate all files in one and print them to STDOUT • % cat > filename • Will take whatever you type from STDIN and will put it into the file filename • To exit cat or cat > filename type Ctrl+D to indicate EOF (End of File).

46. more / less • Pagers to display contents of large files page by page or scroll line by line up and down. • Have a lot of viewing options and search capability. • Interactive. To exit: ‘q’

47. less • less ("less is more") a bit more smart than the more command • to display contents of a file: • % less filename • To display line numbers: • % less -N filename • To display a prompt: • % less -P"Press 'q' to quit" filename • Combine the two: • % less -NP"Blah-blah-blah" filename • For more information: • % man less

48. touch • By touching a file you either create it if it did not exists (with 0 length). • Or you update it’s last modification and access times. • There are options to override the default behavior. • % touch file • % man touch

49. cp • Copies files / directories. • % cp [options] <source> <destination> • % cp file1 file2 • % cp file1 [file2] … /directory • Useful option: -i to prevent overwriting existing files and prompt the user to confirm.

50. mv • Moves or renames files/directories. • % mv <source> <destination> • The <source> gets removed • % mv file1 dir/ • % mv file1 file2 • rename • % mv file1 file2 dir/ • % mv dir1 dir2