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

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

We will talk a bit about avoiding snake oil, getting rid of cognitive biases when planning application security, and how to avoid becoming cryptography professor when you only need to protect your app.

By Anastasiia Voitova. Original slides: https://speakerdeck.com/vixentael/avoiding-damage-shame-and-regrets-data-protection-for-mobile-client-server-architectures

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do{iOS} conference

November 09, 2015
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Transcript

  1. 7.

    Birds fly away, Eve doesn’t hear them data protection for

    client-server apps #doios @vixentael secure place hear nothing
  2. 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 #doios @vixentael
  3. 11.

    What we protect? User’s data! data protection for client-server apps

    #doios @vixentael in storage in motion in memory
  4. 13.

    There are hackers.. and threats these hackers exploit.. to create

    damage data protection for client-server apps #doios @vixentael Problem: Layer 1
  5. 15.

    Client and Server are communicating data protection for client-server apps

    #doios @vixentael passw: 123456 HTTP 1.1 Alice-the-App Bob-the-Server
  6. 18.

    Here Eve-the-Hacker comes! passw: 123456 HTTP 1.1 data protection for

    client-server apps #doios @vixentael {“passw”:“123456”}
  7. 19.

    Let’s go deeper.. To avoid threats we need secure programming

    data protection for client-server apps #doios @vixentael Problem: Layer 2
  8. 21.
  9. 22.

    ..and they decide to use HTTPS! data protection for client-server

    apps #doios @vixentael ****** : ****** HTTPS out of the box
  10. 23.

    But it’s not really secure.. ****** : ****** HTTPS out

    of the box data protection for client-server apps #doios @vixentael {“passw”:“123456”}
  11. 24.

    Intercept traffic using proxy data protection for client-server apps #doios

    @vixentael * SSL experimenting with Android Top100 apps http://bit.ly/1NqpheM * Intercepting the App Store's Traffic on iOS http://bit.ly/1H3xMrs
  12. 25.

    What helps Eve to eavesdrop? ๏ not encrypting user data

    data protection for client-server apps #doios @vixentael ๏ plain HTTP ๏ self-signed certificates ๏ HTTPS with old cipher-suites ๏ using vulnerable libraries and bad examples from StackOverflow ๏ SSL without SSL certificate pinning
  13. 26.
  14. 27.

    data protection for client-server apps #doios @vixentael 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
  15. 28.

    ๏ Copying bad code from StackOverflow ๏ Debugging by tearing

    security suites apart ๏ Avoiding “complicated” security documentation data protection for client-server apps #doios @vixentael Software is buggy. Why?
  16. 29.

    - is easy to f*ck up - is inconvenient to

    implement Cyber-world security
  17. 30.

    - use good practice and brain - use good tools

    - minimize re-inventing the wheel What shall we do?
  18. 31.

    data protection for client-server apps #doios @vixentael Realize threat vectors

    Bad cryptography No access control Authentication bypass Credential reuse Session hijacking Denial of Service Data leakage …
  19. 32.

    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 data protection for client-server apps #doios @vixentael Implementing security tools yourself is a threat
  20. 34.
  21. 35.

    Use great tools scientific background trust big guys good track

    record data protection for client-server apps #doios @vixentael 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
  22. 38.

    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: data protection for client-server apps #doios @vixentael https://www.owasp.org/index.php/ Transport_Layer_Protection_Cheat_Sheet
  23. 40.

    SSL/TLS in short data protection for client-server apps #doios @vixentael

    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
  24. 41.

    Where can it break? data protection for client-server apps #doios

    @vixentael 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
  25. 42.

    SSL pinning data protection for client-server apps #doios @vixentael hello

    client asks certificate server sends cert encrypted data client verifies cert - compares cert against pinned cert key negotiation
  26. 43.

    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 #doios @vixentael
  27. 44.

    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!")
 } data protection for client-server apps #doios @vixentael Swift lib for HTTPS and SSL pinning https://github.com/johnlui/Pitaya https://github.com/iSECPartners/ssl-conservatory
  28. 47.

    Forward Secrecy: Threat Eve records encrypted traffic New crypto vulnerability

    allows to exact keys Eve physically extracts keys from one of the birds Eve decrypts all encrypted traffic data protection for client-server apps #doios @vixentael
  29. 48.

    Forward Secrecy: Mitigation Forward Secrecy ephemeral keys + key rotation

    scheme data protection for client-server apps #doios @vixentael https://weakdh.org/imperfect-forward-secrecy-ccs15.pdf SSL/TLS has forward secrecy but it’s weak: =
  30. 49.

    Using ephemeral key data protection for client-server apps #doios @vixentael

    key negotiation (RSA or EC) create symmetric temp key use temp key to encrypt messages during session close session open session
  31. 50.

    Implementing ephemeral keys 1. establish session 2. encrypt message with

    SecureSession before sending 3. decrypt message after receive 4. encrypt history with SecureCell data protection for client-server apps #doios @vixentael https://github.com/cossacklabs/themis Themis has built-in forward secrecy inside SecureSession object
  32. 51.

    Implementing ephemeral keys data protection for client-server apps #doios @vixentael

    https://github.com/cossacklabs/mobile-websocket-example
  33. 53.

    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 #doios @vixentael
  34. 55.

    data protection for client-server apps #doios @vixentael Storing the keys

    SSKeychain example Valet example https://github.com/square/Valet https://github.com/soffes/sskeychain
  35. 56.

    compute key and use KDF to derive data protection for

    client-server apps #doios @vixentael 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))
  36. 58.

    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 #doios @vixentael
  37. 59.

    Alice is more secure now data protection for client-server apps

    #doios @vixentael SSL pinning encrypted storage data ephemeral keys
  38. 60.

    Bob is more secure now data protection for client-server apps

    #doios @vixentael encrypted storage data ephemeral keys
  39. 61.

    Chatting is more secure 5720b3c2 fe674f54 73e10ad4 ... HTTPS SSL

    pinning ephemeral keys data protection for client-server apps #doios @vixentael
  40. 63.

    The last slide @vixentael iOS developer at stanfy.com [creating awesome

    mobile and IoT apps] data protection for client-server apps #doios @vixentael take care!
  41. 64.

    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/
  42. 65.

    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