Avoiding damage, shame and regrets: data protection for mobile client-server architectures

If you can't tap on the link inside slides, please open as pdf (button on the right).

-------------------
-------------------

Blog post
https://medium.com/@vixentael/data-protection-for-mobile-client-server-architectures-6e6dcabd871a

My talk at #doios (Amsterdam), #CocoaConfBy (Minks) and #CocoaHeadsKyiv conferences =)

- communication with server: security, reliability, ease of use, choose two
- applied cryptography: should you manually configure CommonCrypto or ...?
- practical example: protecting network transport without breaking the app
- storage security: how to prevent anyone reading your sexy chat messages

Transcript

1. Avoiding damage, shame and regrets data protection for mobile client-server architectures @vixentael
2. is intuitive, evolution trained us for it Real-world security
3. Meet Dodo birds! Alice Bob data protection for client-server apps @vixentael
4. They are chatting together Alice Bob tweet hello data protection for client-server apps @vixentael
5. Here comes Eve.. ..the eavesdropping Fennec Fox data protection for client-server apps @vixentael
6. Eve eavesdrops danger tweet ack ear radars: ON data protection for client-server apps @vixentael
7. Birds fly away, Eve doesn’t hear them secure place hear nothing data protection for client-server apps @vixentael
8. Risk (threat): Eve hears your secrets Mitigation: physically move away from Eve Real-world security
9. evolution did not prepare you for that! Cyber-world security
10. Apple Secure Coding Guide Every program is a potential target. Your customers’ property and your reputation are at stake. https://developer.apple.com/library/mac/documentation/ Security/Conceptual/SecureCodingGuide/ Introduction.html data protection for client-server apps @vixentael
11. What we protect? User’s data! in storage in motion in memory data protection for client-server apps @vixentael
12. Data in motion
13. There are hackers.. and threats these hackers exploit.. to create damage Problem: Layer 1 data protection for client-server apps @vixentael
14. Meet Alice-the-App and Bob-the-Server Alice-the-App Bob-the-Server data protection for client-server apps @vixentael
15. Client and Server are communicating passw: 123456 HTTP 1.1 Alice-the-App Bob-the-Server data protection for client-server apps @vixentael
16. Eve-the-Hacker data protection for client-server apps @vixentael
17. Here Eve-the-Hacker comes! passw: 123456 HTTP 1.1 data protection for client-server apps @vixentael
18. Here Eve-the-Hacker comes! passw: 123456 HTTP 1.1 {“passw”:“123456”} data protection for client-server apps @vixentael
19. Let’s go deeper.. To avoid threats we need secure programming Problem: Layer 2 data protection for client-server apps @vixentael
20. Alice decides to implement security puts on paper hat! data protection for client-server apps @vixentael
21. Bob decides to implement security builds the fence! data protection for client-server apps @vixentael
22. ..and they decide to use HTTPS! ****** : ****** HTTPS out of the box data protection for client-server apps @vixentael
23. But it’s not really secure.. ****** : ****** HTTPS out of the box {“passw”:“123456”} data protection for client-server apps @vixentael
24. Intercept traffic using proxy (1) data protection for client-server apps @vixentael
25. Intercept traffic using proxy (2) data protection for client-server apps @vixentael
26. Intercept traffic using proxy (3) * SSL experimenting with Android Top100 apps http://bit.ly/1NqpheM * Intercepting the App Store's Traffic on iOS http://bit.ly/1H3xMrs data protection for client-server apps @vixentael
27. What helps Eve to eavesdrop? ๏ not encrypting user data ๏ plain HTTP ๏ self-signed certificates ๏ HTTPS with old cipher-suites ๏ using vulnerable libraries and bad examples from StackOverflow ๏ SSL without SSL certificate pinning data protection for client-server apps @vixentael
28. Problem: Layer 3 As the result, Programming is rarely secure data protection for client-server apps @vixentael
29. Software is buggy http://blog.mindedsecurity.com/2015/03/ssl-mitm-attack-in-afnetworking-251- do.html AFNetworking SSL verification bug (v2.5.1-2.5.2) https://eprint.iacr.org/2013/049.pdf Out-of-the-box SSL is frequent subject to attacks http://www.dwheeler.com/essays/apple-goto-fail.html Apple “goto fail” vulnerability http://noxxi.de/howto/ssl-debugging.html data protection for client-server apps @vixentael
30. ๏ Copying bad code from StackOverflow ๏ Debugging by tearing security suites apart ๏ Avoiding “complicated” security documentation Software is buggy. Why? data protection for client-server apps @vixentael
31. - is easy to f*ck up - is inconvenient to implement Cyber-world security
32. - use good practice and brain - use good tools - minimize re-inventing the wheel What shall we do?
33. Realize threat vectors Bad cryptography No access control Authentication bypass Credential reuse Session hijacking Denial of Service Data leakage … data protection for client-server apps @vixentael
34. Anyone can invent a security system that he himself cannot break — Schneier's Law https://www.schneier.com/blog/archives/ 2011/04/schneiers_law.html Implementing security tools yourself is a threat data protection for client-server apps @vixentael
35. Do not re-implement existing things data protection for client-server apps @vixentael
37. Use great tools scientific background trust big guys good track record libsodium/NaCL OTRKit RNCryptor MIHCrypto Themis https://github.com/mochtu/libsodium-ios https://github.com/ChatSecure/OTRKit https://github.com/RNCryptor/RNCryptor https://github.com/hohl/MIHCrypto https://github.com/cossacklabs/themis data protection for client-server apps @vixentael
38. Apple open sourced crypto data protection for client-server apps @vixentael
39. Swift CommonCrypto wrapper https://github.com/iosdevzone/IDZSwiftCommonCrypto/ https://realm.io/news/danny-keogan-swift-cryptography/ https://news.ycombinator.com/item?id=10733215 data protection for client-server apps @vixentael
40. Armoring your SSL
41. Do your SSL/TLS right ๏use long keys ๏disable backward compatibility ๏use strong ciphers (EC vs RSA) ๏pin SSL certificate ๏use cheat sheet https://www.cossacklabs.com/avoid-ssl-for-your- next-app.html SSL has a lot of problems To survive you need to: https://www.owasp.org/index.php/ Transport_Layer_Protection_Cheat_Sheet data protection for client-server apps @vixentael
42. Do you pin SSL certificate? data protection for client-server apps @vixentael
43. SSL/TLS in short hello client asks certificate server sends cert encrypted data client verifies cert - domain, - expiration date, - asks CA if cert is valid and not revoked key negotiation data protection for client-server apps @vixentael
44. Where can it break? hello client asks certificate server sends cert encrypted data client verifies cert - domain, - expiration date, - asks CA if cert is valid and not revoked key negotiation data protection for client-server apps @vixentael
45. SSL pinning hello client asks certificate server sends cert encrypted data client verifies cert - compares cert against pinned cert key negotiation data protection for client-server apps @vixentael
46. SSL pinning on iOS https://possiblemobile.com/2013/03/ssl-pinning-for-increased-app-security/ https://www.paypal-engineering.com/2015/10/14/key-pinning-in-mobile- applications/ - (void)connection:(NSURLConnection *)connection willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge { SecTrustRef serverTrust = challenge.protectionSpace.serverTrust; id<NSURLAuthenticationChallengeSender> sender = challenge.sender; SecCertificateRef certificate = SecTrustGetCertificateAtIndex(serverTrust, 0); NSData * remoteCertificateData = CFBridgingRelease(SecCertificateCopyData(certificate)); NSString * cerPath = [[NSBundle mainBundle] pathForResource:@"MyLocalCertificate" ofType:@"cer"]; NSData * localCertData = [NSData dataWithContentsOfFile:cerPath]; if ([remoteCertificateData isEqualToData:localCertData]) { NSURLCredential * credential = [NSURLCredential credentialForTrust:serverTrust]; [sender useCredential:credential forAuthenticationChallenge:challenge]; } else { [sender cancelAuthenticationChallenge:challenge]; } } data protection for client-server apps @vixentael
47. SSL pinning more easy :) let certData = NSData(contentsOfFile: NSBundle.mainBundle().pathForResource("lvwenhancom", ofType: "cer")!)!
 ... ... .addSSLPinning(LocalCertData: certData) { () -> Void in
 print("Under Man-in-the-middle attack!")
 } Swift lib for HTTPS and SSL pinning https://github.com/johnlui/Pitaya https://github.com/iSECPartners/ssl-conservatory data protection for client-server apps @vixentael
48. Nah. SSL is not enough :( So, we’re done?
49. Government MitM http://habrahabr.ru/post/272207/ data protection for client-server apps @vixentael
50. Implementing Forward Secrecy
51. Forward Secrecy: Threat Eve records encrypted traffic New crypto vulnerability allows to extract keys Eve physically extracts keys from one of the birds Eve decrypts all encrypted traffic data protection for client-server apps @vixentael
52. data protection for client-server apps @vixentael Forward Secrecy: Mitigation Forward Secrecy ephemeral keys + key rotation scheme https://weakdh.org/imperfect-forward-secrecy-ccs15.pdf SSL/TLS has forward secrecy but it’s weak: =
53. Using ephemeral key key negotiation (RSA or EC) create symmetric temp key use temp key to encrypt messages during session close session open session data protection for client-server apps @vixentael
54. Implementing ephemeral keys 1. establish session 2. encrypt message with SecureSession before sending 3. decrypt message after receive 4. encrypt history with SecureCell https://github.com/cossacklabs/themis Themis has built-in forward secrecy inside SecureSession object data protection for client-server apps @vixentael
55. Implementing ephemeral keys https://github.com/cossacklabs/mobile-websocket-example data protection for client-server apps @vixentael
56. Data in storage
57. iOS data protection data protection for client-server apps @vixentael
58. Storing in plain text is bad idea data protection for client-server apps @vixentael
59. What we need to do 1. Choose good storage library with efficient crypto 2. Embed it on read/write 3. Store keys safely data protection for client-server apps @vixentael
60. RNCryptor example Themis SecureCell example Storage libraries data protection for client-server apps @vixentael
61. Storing the keys SSKeychain example Valet example https://github.com/square/Valet https://github.com/soffes/sskeychain data protection for client-server apps @vixentael
62. compute key and use KDF to derive Storing the keys: Computable obfuscation https://www.mikeash.com/pyblog/friday-qa-2012-08-10-a-tour-of- commoncrypto.html key = KDF(sqrt(42)*len(user_id)/parity(user_id)) data protection for client-server apps @vixentael
63. Ending notes
64. Practical app security step by step 1.Use HTTPS with good TLS settings 2.Enable SSL pinning 3.Encrypt user data in motion with ephemeral keys 4.Encrypt stored data and protect the key data protection for client-server apps @vixentael
65. Alice is more secure now SSL pinning encrypted storage data ephemeral keys data protection for client-server apps @vixentael
66. Bob is more secure now encrypted storage data ephemeral keys data protection for client-server apps @vixentael
67. data protection for client-server apps @vixentael Chatting is more secure 5720b3c2 fe674f54 73e10ad4 ... HTTPS SSL pinning ephemeral keys
68. Security is full of adventures and discoveries. And fun. and shiny metal birds!
69. The last slide @vixentael iOS developer at stanfy.com [creating awesome mobile and IoT apps] take care! data protection for client-server apps @vixentael
70. More to read ̣ The Mobile Application Hacker's Handbook https://books.google.com.ua/books?id=UgVhBgAAQBAJ ̣ Designing Secure User Interfaces https://developer.apple.com/library/ios/documentation/Security/ Conceptual/SecureCodingGuide/Articles/AppInterfaces.html#//apple_ref/ doc/uid/TP40002862-SW1 ̣ CryptoCat iOS app security audit https://nabla-c0d3.github.io/documents/iSEC_Cryptocat_iOS.pdf ̣ Storing secret keys http://www.splinter.com.au/2014/09/16/storing-secret-keys/
71. More to watch ̣ All talks of Moxie Marlinspike https://www.youtube.com/watch?v=ibF36Yyeehw https://www.youtube.com/watch?v=8N4sb-SEpcg https://www.youtube.com/watch?v=tOMiAeRwpPA