Building DEF CON CTF with Ruby

Presented at Big Ruby Conference, Grapevine, TX, Feb. 20 2014

1. Building DEF CON CTF with Ruby
2. Hello Vito Genovese @vito_lbs vito@legitbs.net
3. Building DEF CON CTF •DEF CON and CTF •Team building •Qualifications •Finals
4. What is DEF CON? “DEF CON is one of the oldest continuous running hacker conventions around, and also one of the largest.” - DEF CON FAQ
5. What is DEF CON? “Black Hat… is more the university… DEF CON is the fraternity party.” - USA Today, “Suits and punks convene in Las Vegas for hacker conferences,” Aug. 1 2006
6. What is DEF CON?
7. What is DEF CON?
8. What is CTF? (Capture The Flag)
9. Jeopardy-Style CTF •Pick a problem •Hack it •Get points
10. Attack-Defense CTF 1. Hack services 2. Steal tokens every round 3. Get points 1. Patch services 2. Pass SLA checks 3. Don’t lose points
11. Competing in CTF •Build a team •Get really good at assembly •Get good at web vulns and crypto too •Compete and solve problems •Write up solutions
12. Competing in CTF
13. Sample Challenges http://hypeman.shallweplayaga.me http://worsemedicine.shallweplayaga.me
14. Hour 30
15. Building DEF CON CTF •DEF CON and CTF •Team building •Qualifications •Finals
16. Team Building “Dark Tangent is looking for new CTF organizers, want to help write a proposal?”
17. Team Building Software vulnerability experts Hardware engineers Network ops deity Web application generalist
18. Team Building •Opinionated smart people •That need to work together •On a software project with dozens of moving parts •On a very public stage •With immovable deadlines
19. Team Building Always have an exit strategy
20. Building DEF CON CTF •DEF CON and CTF •Team building •Qualifications •Finals
21. Qualifications “Quals”
22. Quals “Jeopardy-style” Self-contained questions Open Entry 48 hours over a weekend
24. Quals Scoreboard Rails Unicorn Heroku 1GB Dynos $50/month Postgres
25. Quals Scoreboard No Redis No memcached
26. Quals Scoreboard No push Only polling
27. Quals Scoreboard
28. Quals Scoreboard
29. Quals Scoreboard Game Start Adjusting dynos
30. Quals Challenges •Sinatra •PHP •Python •x86 •Golang •ARM
31. Sinatra Used Heroku It ruled
32. PHP, Python, x86, Golang EC2 Started with Micro Upgraded to Large
33. PHP, Python, x86, Golang Never use Micro instances
34. PHP, Python, x86, Golang Sometimes you get DoS’d
35. ARM Challenges
36. Quals Problems I slept… Through a part where we had to edit a question and put something on S3.
37. Quals Problems Some challenges weren’t ready until halfway through the game
38. https://twitter.com/roman_soft/status/346325078369263616
39. Quals •IRC and Twitter: invaluable •Have a reset password flow •Don’t forget public views •Fight bus numbers
40. Building DEF CON CTF •DEF CON and CTF •Team building •Qualifications •Finals
41. Finals OMG
43. Finals http://www.cnbc.com/id/101179977
44. Finals
45. Finals
46. Finals Twenty Teams Twenty Servers One Network
47. Finals •Attack-defense style •Teams get a server running services •Find vulnerabilities in services •Patch own vulnerabilities •Exploit vulnerabilities on other teams
48. Finals Scoring Fifty-thousand flags Five-minute rounds Tokens from services redeemed for flags Flags lost when stolen and downtime Zero-sum for game theory reasons
49. Finals Scoreboard Rails, Apache, Passenger, Postgres Ubuntu on Mac Mini HTTPS Client Certificates Kibana (Logstash, Elasticsearch) No push, no polling, just meta refresh
50. Finals Scoreboard Client certs rule No password resets No hacking, no sniffing Twenty CDs of certs and keys… eh
51. Kibana
54. Kibana Log Everything
55. Tokens and Uptime Console Ruby script Restartable in a sensible fashion Use Postgres and wall clock time as state Save immediately, don’t queue
56. Tokens and Uptime Two weeks prior: “I’m just going to call a shell script, everyone else write your own uptime checker.”
57. Tokens and Uptime Three hours in: “Uh, how do we make these shell scripts time out?”
58. Tokens and Uptime Ten hours in: “We should run these in parallel.”
59. Tokens and Uptime Sixteen hours in: “Huh some team is puking binary out.”
60. Finals Problems Teams could score on themselves
61. Finals Problems Flags didn’t get redistributed correctly
62. Finals Problems Have a better way to find issues than rails console, SQL, and log queries
64. Finals Problems API Documentation
65. Finals Problems Life’s easy when you have 160 users and they’re all right there
66. Finals Team Boxes
67. Finals Team Boxes Services run as dedicated users Teams have sudo to service No root
69. Finals Lessons Scheduled downtime is the best
70. Building DEF CON CTF •DEF CON and CTF •Team building •Qualifications •Finals
71. Lessons Stuff will break
72. Lessons Own your mistakes
73. Lessons Fight scope creep
74. Lessons JFDI
75. Thanks Vito Genovese @vito_lbs vito@legitbs.net https://legitbs.net http://bit.ly/br-ctf
76. Bonus Slides
77. DEF CON and Jeopardy
78. Quals Expenses What How much Heroku $126 AWS $138 Cloudflare $20 Whisky $340
79. Finals Services ARM binaries ASLR, NX bit, some PIE
80. Finals Services Release new services Update existing services
81. Finals Team Boxes Boot from MicroSD Start container from iSCSI