Man in the Middle? - No, thank you!

1. No,$thank$you! MAN$IN$THE$MIDDLE$? Daniel$Schneller$–$CenterDevice$GmbH

2. SSL$–$and$you’re$done™

3. SSL$–$and$you’re$done™

4. SSL$–$and$you’re$done™ …are$you?

5. Mac$App$Store

6. Mac$App$Store

7. Mac$App$Store

8. Outbank

9. What$happened$to$SSL?

10. SSL$–$Chain$of$Trust

11. SSL$–$Chain$of$Trust Root$CA$Cer)ﬁcate

12. SSL$–$Chain$of$Trust Root$CA$Cer)ﬁcate $Intermediate$CA$Cer)ﬁcate(s)issues

13. SSL$–$Chain$of$Trust Root$CA$Cer)ficate $Intermediate$CA$Cer)ficate(s) Leaf$Cer)ficate issues issues

20. Just$how$many$Root$CAs$ are$there?

21. System$Roots

22. System$Roots

23. System$Roots Windows$8:$~350 Mozilla:$~160 iOS$6:$~220

24. Man$In$The$Middle?

25. Man$In$The$Middle [Corporate]$Proxy Client

28. Man$In$The$Middle Website [Corporate]$Proxy Client

32. Man$In$The$Middle

38. Consequences •Monitoring •ManipulaZon •Sent$and$received$data$aﬀected •ChainOfTrust$formally$veriﬁed

39. Good$and$evil •Debugging •Reverse$Engineering •Security$Audits •Learning$and$Understanding

40. ReST$Debugging

41. Good$and$evil •Phishing •IdenZty$The` •Industrial$Espionage •…

42. Mac$App$Store

43. Mac$App$Store

44. Mac$App$Store

45. iTunes

46. iTunes

47. iTunes

48. Demo$1 Video$1 Video$2

49. Countermeasures

50. Reference$CerZﬁcates

51. Reference$CerZficates •Client$bundles$server$cerZficate$as$a$ reference •Compare$reference$and$cerZficate$sent$by$ the$server$ •Connect$only$when$there’s$a$perfect$match

52. Reference$CerZﬁcates $Client$App$Server

53. Reference$CerZﬁcates $Client$App$Server ==

54. Reference$CerZﬁcates SecTrustResultType evaluationResult; OSStatus status = SecTrustEvaluate(srvTrust, &evaluationResult); if (status == errSecSuccess) { if (evaluationResult == kSecTrustResultUnspecified) { // ... } } •Step$1:$$Validate$ChainofTrust

55. Reference$CerZﬁcates SecTrustResultType evaluationResult; OSStatus status = SecTrustEvaluate(srvTrust, &evaluationResult); if (status == errSecSuccess) { if (evaluationResult == kSecTrustResultUnspecified) { // ... } } •Step$1:$$Validate$ChainofTrust

56. Reference$CerZﬁcates •Step$1:$$Validate$ChainofTrust SecTrustResultType evaluationResult; OSStatus status = SecTrustEvaluate(srvTrust, &evaluationResult); if (status == errSecSuccess) { if (evaluationResult == kSecTrustResultUnspecified) { // ... } }

60. NSString *refPath = [[NSBundle mainBundle] pathForResource:@"reference" ofType:@"der"]; NSData *refCertData = [[NSData alloc] initWithContentsOfFile:refPath]; Reference$CerZﬁcates •Step$2:$Load$Reference$CerZﬁcate

61. NSString *refPath = [[NSBundle mainBundle] pathForResource:@"reference" ofType:@"der"]; NSData *refCertData = [[NSData alloc] initWithContentsOfFile:refPath]; Reference$CerZﬁcates •Step$2:$Load$Reference$CerZﬁcate

62. Reference$CerZﬁcates •Step$2:$Load$Reference$CerZﬁcate NSString *refPath = [[NSBundle mainBundle] pathForResource:@"reference" ofType:@"der"]; NSData *refCertData = [[NSData alloc] initWithContentsOfFile:refPath];

63. Reference$CerZﬁcates BOOL found = NO; CFIndex crtCount = SecTrustGetCertificateCount(srvTrust); for (CFIndex j = 0; j < crtCount && !found; j++) { SecCertificateRef cert = SecTrustGetCertificateAtIndex(srvTrust, j); NSData* certData = CFBridgingRelease(SecCertificateCopyData(cert)); found = [refCertData isEqualToData:certData]; } •Step$3:$Compare$cerZﬁcates

64. Reference$CerZﬁcates BOOL found = NO; CFIndex crtCount = SecTrustGetCertificateCount(srvTrust); for (CFIndex j = 0; j < crtCount && !found; j++) { SecCertificateRef cert = SecTrustGetCertificateAtIndex(srvTrust, j); NSData* certData = CFBridgingRelease(SecCertificateCopyData(cert)); found = [refCertData isEqualToData:certData]; } •Step$3:$Compare$cerZﬁcates

65. Reference$CerZﬁcates •Step$3:$Compare$cerZﬁcates BOOL found = NO; CFIndex crtCount = SecTrustGetCertificateCount(srvTrust); for (CFIndex j = 0; j < crtCount && !found; j++) { SecCertificateRef cert = SecTrustGetCertificateAtIndex(srvTrust, j); NSData* certData = CFBridgingRelease(SecCertificateCopyData(cert)); found = [refCertData isEqualToData:certData]; }

70. Demo$2 Video

71. FingerprinZng

72. FingerprinZng •Similar$to$Reference$CerZficate$approach •Compares$CerZficate$Fingerprint$against$ reference$value •Server$CerZficate$not$needed$in$the$client •Example:$$Apple$So`ware$Update

73. FingerprinZng$ $Client$App$Server 1122 3344 5566 7788 9900 AABB CCDD EEFF 9988 7766 SHA-1 Hash

74. FingerprinZng$ $Client$App$Server 1122 3344 5566 7788 9900 AABB CCDD EEFF 9988 7766 SHA-1 Hash

75. FingerprinZng$ $Client$App$Server == 1122 3344 5566 7788 9900 AABB CCDD EEFF 9988 7766 SHA-1 Hash 1122 3344 5566 7788 9900 AABB CCDD EEFF 9988 7766

76. FingerprinZng •Schrie$1:$ChainofTrust$validieren SecTrustResultType evaluationResult; OSStatus status = SecTrustEvaluate(srvTrust, &evaluationResult); if (status == errSecSuccess) { if (evaluationResult == kSecTrustResultUnspecified) { // ... } }

77. FingerprinZng static NSString* const kReferenceFP = @"AC .... DC"; BOOL found = NO; CFIndex crtCount = SecTrustGetCertificateCount(srvTrust); for (CFIndex j = 0; j < crtCount && !found; j++) { SecCertificateRef cert = SecTrustGetCertificateAtIndex(srvTrust, j); NSData* certData = CFBridgingRelease(SecCertificateCopyData(cert)); NSString* fingerprint = [self sha1:certData]; found = [kReferenceFP isEqualToString:fingerprint] } •Schrie$2:$Fingerprint$berechnen

78. FingerprinZng static NSString* const kReferenceFP = @"AC .... DC"; BOOL found = NO; CFIndex crtCount = SecTrustGetCertificateCount(srvTrust); for (CFIndex j = 0; j < crtCount && !found; j++) { SecCertificateRef cert = SecTrustGetCertificateAtIndex(srvTrust, j); NSData* certData = CFBridgingRelease(SecCertificateCopyData(cert)); NSString* fingerprint = [self sha1:certData]; found = [kReferenceFP isEqualToString:fingerprint] } •Schrie$2:$Fingerprint$berechnen

79. FingerprinZng •Schrie$2:$Fingerprint$berechnen static NSString* const kReferenceFP = @"AC .... DC"; BOOL found = NO; CFIndex crtCount = SecTrustGetCertificateCount(srvTrust); for (CFIndex j = 0; j < crtCount && !found; j++) { SecCertificateRef cert = SecTrustGetCertificateAtIndex(srvTrust, j); NSData* certData = CFBridgingRelease(SecCertificateCopyData(cert)); NSString* fingerprint = [self sha1:certData]; found = [kReferenceFP isEqualToString:fingerprint] }

86. Demo$3 Video

87. Caveats

88. Caveats •Change$of$CerZﬁcate •Expired •Compromised •Update$app$with$plenty$of$lead$Zme •Temporarily$accept$old$and$new$ cerZﬁcates

89. VariaZon

90. VariaZon •Check$RootCerZﬁcate$against$reference •TradeOﬀ:$Flexibility$vs.$Security •Updates$only$required$when$changing$ RootCA

91. Conclusions

92. Conclusions •SSL$provides •ConﬁdenZality$(encrypted) •AuthenZcity •CA$system$(usually)$suﬃecient •More$Security$=$More$Work

93. Make$informed$ decisions!

94. Links Sample,Code •github.com/dschneller/mitmnothankyou Tools •github.com/ADVTOOLS/ADVcerZﬁcator •github.com/ADVTOOLS/ADVTrustStore •www.apple.com/support/iphone/enterprise •technet.microso`.com/enus/library/ cc754841.aspx

95. Links TLS,Session,Cache •developer.apple.com/library/ios/#qa/qa1727 Root6CA,Lists •support.apple.com/kb/HT5012 •www.mozilla.org/projects/security/certs/ included/ •social.technet.microso`.com/wiki/contents/ arZcles/14215.windowsandwindowsphone8 sslrootcerZﬁcateprogrammembercas.aspx •Android:$Sepngs–Security–Trusted$CredenZals

96. Thank$you!

97. QuesZons$? daniel.schneller@centerdevice.de $$$$$@dschneller

98. That’s$all.$Really.$:)

99. Demo$1 Standard$SSL,$ MITM$RootCA$ not$installiert zurück

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Man in the Middle? - No, thank you!