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

vixentael
December 18, 2015

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).

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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

vixentael

December 18, 2015
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  1. Birds fly away, Eve doesn’t hear them secure place hear

    nothing data protection for client-server apps @vixentael
  2. 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
  3. What we protect? User’s data! in storage in motion in

    memory data protection for client-server apps @vixentael
  4. There are hackers.. and threats these hackers exploit.. to create

    damage Problem: Layer 1 data protection for client-server apps @vixentael
  5. Client and Server are communicating passw: 123456 HTTP 1.1 Alice-the-App

    Bob-the-Server data protection for client-server apps @vixentael
  6. Let’s go deeper.. To avoid threats we need secure programming

    Problem: Layer 2 data protection for client-server apps @vixentael
  7. Alice decides to implement security puts on paper hat! data

    protection for client-server apps @vixentael
  8. ..and they decide to use HTTPS! ****** : ****** HTTPS

    out of the box data protection for client-server apps @vixentael
  9. But it’s not really secure.. ****** : ****** HTTPS out

    of the box {“passw”:“123456”} data protection for client-server apps @vixentael
  10. 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
  11. 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
  12. Problem: Layer 3 As the result, Programming is rarely secure

    data protection for client-server apps @vixentael
  13. 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
  14. ๏ 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
  15. - is easy to f*ck up - is inconvenient to

    implement Cyber-world security
  16. - use good practice and brain - use good tools

    - minimize re-inventing the wheel What shall we do?
  17. 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
  18. 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
  19. 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
  20. 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
  21. 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
  22. 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
  23. 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
  24. 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
  25. 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
  26. 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
  27. 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: =
  28. 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
  29. 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
  30. 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
  31. 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
  32. 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
  33. Alice is more secure now SSL pinning encrypted storage data

    ephemeral keys data protection for client-server apps @vixentael
  34. Bob is more secure now encrypted storage data ephemeral keys

    data protection for client-server apps @vixentael
  35. data protection for client-server apps @vixentael Chatting is more secure

    5720b3c2 fe674f54 73e10ad4 ... HTTPS SSL pinning ephemeral keys
  36. The last slide @vixentael iOS developer at stanfy.com [creating awesome

    mobile and IoT apps] take care! data protection for client-server apps @vixentael
  37. 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/
  38. 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