Near Field Communication Security

Transcription

1 Near Field Communication Security Thomas Patzke

2 Who am I... Thomas Patzke (formerly Skora)

3 Who am I... Thomas Patzke (formerly Skora) Started with security related topics somewhere in the 90s University degree in 2006, RWTH Aachen, thesis about VoIP security Security Consulting since 2006 Primary security analysis/penetration testing

4 Who am I... Thomas Patzke (formerly Skora) Started with security related topics somewhere in the 90s University degree in 2006, RWTH Aachen, thesis about VoIP security Security Consulting since 2006 Primary security analysis/penetration testing (Web) Application Security Security analysis of unusual stuff: POS, cash machines, head units, security protocols Security Research in various areas Writing Security Tools Cryptography

5 What is this talk about? A introduction to NFC

6 What is this talk about? A introduction to NFC Security of the girogo system Security of Credit Cards How doors get open with replay attacks

7 What is this talk about? A introduction to NFC Security of the girogo system Security of Credit Cards How doors get open with replay attacks Securing NFC applications The NFC hackers toolbox

8 NFC=?

9 NFC=?

10 NFC=... Near Field Communication

11 NFC=... Near Field Communication Few cm communication distance Power supply by reader

12 NFC=... Near Field Communication Few cm communication distance Power supply by reader 13,56 MHz, 424kBit/s

13 NFC=... Near Field Communication Few cm communication distance Power supply by reader 13,56 MHz, 424kBit/s ISO standards 14443: Physical layer, frequency, transmitting power, initialisation, anti-collision, bit transfer 15693: Increased communication distance up to 1,5m 18092, 21481: NFCIP - NFC Interface and Protocol

14 Other systems

15 Other systems 125 khz Proximity Cards: Access Control

16 Other systems 125 khz Proximity Cards: Access Control Legic Prime: Proprietary in 13,56MHz, Access Control, Company Cards

17 Other systems 125 khz Proximity Cards: Access Control Legic Prime: Proprietary in 13,56MHz, Access Control, Company Cards iclass,...

18 Other systems 125 khz Proximity Cards: Access Control Legic Prime: Proprietary in 13,56MHz, Access Control, Company Cards iclass,... NFC RFID

19 Use Cases Access Control Payment Tickets in Public Transportation Determination of Position Verification of Ownership Smart Posters Business Cards Personalized Key Generally: Storage

20

21 Power Supply & Communication Basics Power supply via induction field

22 Power Supply & Communication Basics Power supply via induction field Two transmission modes: passive and active

23 Power Supply & Communication Basics Power supply via induction field Two transmission modes: passive and active Passive Connectionless Roles: Initiator (Reader) and Target (Tag/Card) Request/Response communication

24 Power Supply & Communication Basics Power supply via induction field Two transmission modes: passive and active Passive Connectionless Roles: Initiator (Reader) and Target (Tag/Card) Request/Response communication Active Connection-oriented Equal communication partners Unusual

25 Low Level Communication ISO : Initialization and Anticollision 8 Bit + 1 Parity Bit Basic Protocol: Command + Parameter + Data + CRC

26 Low Level Communication ISO : Initialization and Anticollision 8 Bit + 1 Parity Bit Basic Protocol: Command + Parameter + Data + CRC ISO : Transmission Protocol Length + Format + Interface Bytes + Historical Bytes + Data + CRC Interface Bytes: communication options (optional) Historical Bytes: misc. infos (optional, ISO )

27 Anti Collision Protocol Usual Question: what happens if multiple cards are in the range of a reader?

28 Anti Collision Protocol Usual Question: what happens if multiple cards are in the range of a reader? Solution: Anticollision Protocol

29 Anti Collision Protocol Usual Question: what happens if multiple cards are in the range of a reader? Solution: Anticollision Protocol Initiator chooses target by unique target identifiers (UIDs) Some kind of binary search: targets send UID prefixes, initiator chooses

30 Anti Collision Protocol Usual Question: what happens if multiple cards are in the range of a reader? Solution: Anticollision Protocol Initiator chooses target by unique target identifiers (UIDs) Some kind of binary search: targets send UID prefixes, initiator chooses Negotiation of higher level protocols

31 Anti Collision Protocol CC BY-NC-SA 2.0 libnfc.org

32 Anti Collision Protocol Any security here?

33 Anti Collision Protocol

34 Anti Collision Protocol

35 Anti Collision Protocol Nope! No transport encryption Overwritten data visible

36 Anticollision Protocol Example 1. R: 26 Welcome (REQA) 2. T: Respond (ATQA) CC BY-NC-SA 2.0 libnfc.org

37 Anticollision Protocol Example 1. R: 26 Welcome (REQA) 2. T: Respond (ATQA) 3. R: Select cascade 1 (SEL) 4. T: cc CT, UID(byte 1,2,3), BCC CC BY-NC-SA 2.0 libnfc.org

38 Anticollision Protocol Example 1. R: 26 Welcome (REQA) 2. T: Respond (ATQA) 3. R: Select cascade 1 (SEL) 4. T: cc CT, UID(byte 1,2,3), BCC 5. R: cc 0e 05 Select available tag (SEL) 6. T: 24 d8 36 Select Acknowledge (SAK) CC BY-NC-SA 2.0 libnfc.org

39 Anticollision Protocol Example 1. R: 26 Welcome (REQA) 2. T: Respond (ATQA) 3. R: Select cascade 1 (SEL) 4. T: cc CT, UID(byte 1,2,3), BCC 5. R: cc 0e 05 Select available tag (SEL) 6. T: 24 d8 36 Select Acknowledge (SAK) 7. R: Select cascade 2 (SEL) 8. T: e1 e3 1c 80 9e UID(byte 4,5,6,7), BCC CC BY-NC-SA 2.0 libnfc.org

40 Anticollision Protocol Example 1. R: 26 Welcome (REQA) 2. T: Respond (ATQA) 3. R: Select cascade 1 (SEL) 4. T: cc CT, UID(byte 1,2,3), BCC 5. R: cc 0e 05 Select available tag (SEL) 6. T: 24 d8 36 Select Acknowledge (SAK) 7. R: Select cascade 2 (SEL) 8. T: e1 e3 1c 80 9e UID(byte 4,5,6,7), BCC 9. R: e1 e3 1c 80 9e b9 e1 Finish select (SEL) 10. T: 20 fc 70 SAK without cascade bit set CC BY-NC-SA 2.0 libnfc.org

41 Anticollision Protocol Example 1. R: 26 Welcome (REQA) 2. T: Respond (ATQA) 3. R: Select cascade 1 (SEL) 4. T: cc CT, UID(byte 1,2,3), BCC 5. R: cc 0e 05 Select available tag (SEL) 6. T: 24 d8 36 Select Acknowledge (SAK) 7. R: Select cascade 2 (SEL) 8. T: e1 e3 1c 80 9e UID(byte 4,5,6,7), BCC 9. R: e1 e3 1c 80 9e b9 e1 Finish select (SEL) 10. T: 20 fc 70 SAK without cascade bit set 11. R: e0 50 bc a5 Request Answer to Select (RATS) 12. T: ATS (DESFire EV1) 13. R: cd Disable (HALT) CC BY-NC-SA 2.0 libnfc.org

42 Lets talk about security!

43 Lets talk about security! NFC itself was made to be contactless, not secure. There is no security at lower protocol layers!

44 Lets talk about security! NFC itself was made to be contactless, not secure. There is no security at lower protocol layers! Security is implemented at the application layer

45 Lets talk about security! NFC itself was made to be contactless, not secure. There is no security at lower protocol layers! Security is implemented at the application layer... if it is implemented.

46 NFC in EC Cards Since end of 2011, Sparkassen in Germany started to issue cards with a contactless payment system.

47 NFC in EC Cards Since end of 2011, Sparkassen in Germany started to issue cards with a contactless payment system. Somewhere in 2012 it was rebranded to girogo

48 NFC in EC Cards Since end of 2011, Sparkassen in Germany started to issue cards with a contactless payment system. Somewhere in 2012 it was rebranded to girogo Basically it is the GeldKarte system with a radio interface. There s an app for reading these cards (S-Reader) Loaded amount of money Validity of card Charging and Payments

49 NFC in EC Cards Since end of 2011, Sparkassen in Germany started to issue cards with a contactless payment system. Somewhere in 2012 it was rebranded to girogo Basically it is the GeldKarte system with a radio interface. There s an app for reading these cards (S-Reader) Loaded amount of money Validity of card Charging and Payments Is this all data?

50 Reverse Engineering of girogo 1. Is there existing information?

51 Reverse Engineering of girogo 1. Is there existing information? Yes: a leaked spec from 1997: EMV specs, publicly available:

52 Reverse Engineering of girogo 1. Is there existing information? Yes: a leaked spec from 1997: EMV specs, publicly available: 2. Decompilation of the app dex2jar jd-gui

53 Reverse Engineering of girogo

54 Reverse Engineering of girogo 1. Is there existing information? Yes: a leaked spec from 1997: EMV specs, publicly available: 2. Decompilation of the app dex2jar jd-gui 3. Built a fuzzer that tries to access further records

55 Reverse Engineering of girogo

56 Reverse Engineering of girogo 1. Is there existing information? Yes: a leaked spec from 1997: EMV specs, publicly available: 2. Decompilation of the app dex2jar jd-gui 3. Built a fuzzer that tries to access further records 4. Built an app that extracts the data It reads everything that the official app reads and additionally...

57 Reverse Engineering of girogo 1. Is there existing information? Yes: a leaked spec from 1997: EMV specs, publicly available: 2. Decompilation of the app dex2jar jd-gui 3. Built a fuzzer that tries to access further records 4. Built an app that extracts the data It reads everything that the official app reads and additionally... The date of activation (boring) bank code number (hmmm) an unique card identifier (privacy) the card number (privacy)

58 Reverse Engineering of girogo 1. Is there existing information? Yes: a leaked spec from 1997: EMV specs, publicly available: 2. Decompilation of the app dex2jar jd-gui 3. Built a fuzzer that tries to access further records 4. Built an app that extracts the data It reads everything that the official app reads and additionally... The date of activation (boring) bank code number (hmmm) an unique card identifier (privacy) the card number (privacy) an account number, but not the customers (what???) for each transaction: the identifier of the counterpart (privacy!)

59 Screenshots

60 Screenshots

61 Screenshots

62 Screenshots

63 Summary of the (short) girogo analysis Payment is secured cryptographically, at least nothing that is breakable in few days.

64 Summary of the (short) girogo analysis Payment is secured cryptographically, at least nothing that is breakable in few days. Kasse2Go (the payment app, very short analysis without retailer card) online verification of retailer card - no possibility was found to convince the backend that I m a retailer. communication with backend is authenticated and encrypted.

65 Summary of the (short) girogo analysis Payment is secured cryptographically, at least nothing that is breakable in few days. Kasse2Go (the payment app, very short analysis without retailer card) online verification of retailer card - no possibility was found to convince the backend that I m a retailer. communication with backend is authenticated and encrypted. No obvious possibilities to interfere the payment process from the network. Payment runs on a smartphone, software under control of potentially malicious merchants.

66 Summary of the (short) girogo analysis Payment is secured cryptographically, at least nothing that is breakable in few days. Kasse2Go (the payment app, very short analysis without retailer card) online verification of retailer card - no possibility was found to convince the backend that I m a retailer. communication with backend is authenticated and encrypted. No obvious possibilities to interfere the payment process from the network. Payment runs on a smartphone, software under control of potentially malicious merchants. Some privacy-relevant information is available via NFC.

67 Summary of the (short) girogo analysis Payment is secured cryptographically, at least nothing that is breakable in few days. Kasse2Go (the payment app, very short analysis without retailer card) online verification of retailer card - no possibility was found to convince the backend that I m a retailer. communication with backend is authenticated and encrypted. No obvious possibilities to interfere the payment process from the network. Payment runs on a smartphone, software under control of potentially malicious merchants. Some privacy-relevant information is available via NFC. How widespread is this app?

68 Summary of the (short) girogo analysis

69 EMV Communication is defined in the EMV standard APDU: CLA + INS + P1 + P2 + Ld + Data + Le EMV further defines a structure somewhat similar to folders (Application IDs) and files

70 EMV Communication is defined in the EMV standard APDU: CLA + INS + P1 + P2 + Ld + Data + Le EMV further defines a structure somewhat similar to folders (Application IDs) and files Activation of the GeldKarte/girogo AID: 00 A4 04 0C 09 D

71 EMV Communication is defined in the EMV standard APDU: CLA + INS + P1 + P2 + Ld + Data + Le EMV further defines a structure somewhat similar to folders (Application IDs) and files Activation of the GeldKarte/girogo AID: 00 A4 04 0C 09 D B2 01 xx 00 reads a data record C4: EF BETRAG (amount of loaded money) CC: EF BOERSE (bank id, account number) 00 B2 xx EC 00: read transactions

72 EMV Communication is defined in the EMV standard APDU: CLA + INS + P1 + P2 + Ld + Data + Le EMV further defines a structure somewhat similar to folders (Application IDs) and files Activation of the GeldKarte/girogo AID: 00 A4 04 0C 09 D B2 01 xx 00 reads a data record C4: EF BETRAG (amount of loaded money) CC: EF BOERSE (bank id, account number) 00 B2 xx EC 00: read transactions Data is clear-text (ASCII) or BCD encoded (25,00 EUR = 0x25 0x00)

73 Lets look at credit cards

74 Lets look at credit cards Mastercard PayPass Visa PayWave

75 Lets look at credit cards Mastercard PayPass Visa PayWave Again looked with the NFC Fuzzer at it...

76 Lets look at credit cards

77 Lets look at credit cards

78 Lets look at credit cards But there is the CVC!!1 The shops must verify it!!!

79 Lets look at credit cards Really?

80 Implementation Details AIDs depend on card, they are printed on receipts and available from public sources, e.g. knowledge-base/211-emv-aid-rid-pix AIDs differ even between countries

81 Implementation Details AIDs depend on card, they are printed on receipts and available from public sources, e.g. knowledge-base/211-emv-aid-rid-pix AIDs differ even between countries Examples for application selection sequences: VISA: 00 A4 04 0C 07 A MasterCard: 00 A4 04 0C 07 A

82 Implementation Details AIDs depend on card, they are printed on receipts and available from public sources, e.g. knowledge-base/211-emv-aid-rid-pix AIDs differ even between countries Examples for application selection sequences: VISA: 00 A4 04 0C 07 A MasterCard: 00 A4 04 0C 07 A The interesting file is requested with: 00 B2 01 0C 00 ASCII encoding

83 Implementation Details AIDs depend on card, they are printed on receipts and available from public sources, e.g. knowledge-base/211-emv-aid-rid-pix AIDs differ even between countries Examples for application selection sequences: VISA: 00 A4 04 0C 07 A MasterCard: 00 A4 04 0C 07 A The interesting file is requested with: 00 B2 01 0C 00 ASCII encoding Implementation (girogo + MasterCard/VISA): github.com/thomaspatzke/android-nfc-paycardreader

84 Summary of Credit Card Vulnerabilities No authentication and authorization before access to sensible data.

85 Summary of Credit Card Vulnerabilities No authentication and authorization before access to sensible data. No transport encryption - data can be sniffed over the air.

86 Summary of Credit Card Vulnerabilities No authentication and authorization before access to sensible data. No transport encryption - data can be sniffed over the air. The insecure magstripe mode shown here is implemented for compatibility reasons. There is a secure EMV mode (aka Chip&PIN)

87 Summary of Credit Card Vulnerabilities No authentication and authorization before access to sensible data. No transport encryption - data can be sniffed over the air. The insecure magstripe mode shown here is implemented for compatibility reasons. There is a secure EMV mode (aka Chip&PIN) Payment process:

88 Summary of Credit Card Vulnerabilities No authentication and authorization before access to sensible data. No transport encryption - data can be sniffed over the air. The insecure magstripe mode shown here is implemented for compatibility reasons. There is a secure EMV mode (aka Chip&PIN) Payment process: 1. Salesperson enters amount 2. Customer puts card on payment terminal 3. After a short time the payment is done

89 Summary of Credit Card Vulnerabilities No authentication and authorization before access to sensible data. No transport encryption - data can be sniffed over the air. The insecure magstripe mode shown here is implemented for compatibility reasons. There is a secure EMV mode (aka Chip&PIN) Payment process: 1. Salesperson enters amount 2. Customer puts card on payment terminal 3. After a short time the payment is done Where is the authorization (PIN entry) gone?

90 Summary of Credit Card Vulnerabilities No authentication and authorization before access to sensible data. No transport encryption - data can be sniffed over the air. The insecure magstripe mode shown here is implemented for compatibility reasons. There is a secure EMV mode (aka Chip&PIN) Payment process: 1. Salesperson enters amount 2. Customer puts card on payment terminal 3. After a short time the payment is done Where is the authorization (PIN entry) gone? The card companies say: putting the card on the terminal is a consent of the card owner!

91 Summary of Credit Card Vulnerabilities No authentication and authorization before access to sensible data. No transport encryption - data can be sniffed over the air. The insecure magstripe mode shown here is implemented for compatibility reasons. There is a secure EMV mode (aka Chip&PIN) Payment process: 1. Salesperson enters amount 2. Customer puts card on payment terminal 3. After a short time the payment is done Where is the authorization (PIN entry) gone? The card companies say: putting the card on the terminal is a consent of the card owner! This is secure the say!

92 Secure? Is the card moved to the payment terminal?

93 Secure? Is the card moved to the payment terminal?... or is the terminal moved to the card?

94 Secure? Is the card moved to the payment terminal?... or is the terminal moved to the card? And then there are relaying attacks

95 Access Control Access control systems are often based on dumb 125kHz tags

96 Access Control Access control systems are often based on dumb 125kHz tags Dumb? Yes, because of this:

97 Access Control Access control systems are often based on dumb 125kHz tags Dumb? Yes, because of this:

98 Securing NFC Systems Personal protection Put your card in sleeves Cut the antenna

99 Securing NFC Systems Personal protection Put your card in sleeves Cut the antenna Building a product?

100 Securing NFC Systems Personal protection Put your card in sleeves Cut the antenna Building a product? Don t use known insecure systems If you re nailed on an insecure system: under certain conditions, vulnerabilities can be mitigated

101 Securing NFC Systems Personal protection Put your card in sleeves Cut the antenna Building a product? Don t use known insecure systems If you re nailed on an insecure system: under certain conditions, vulnerabilities can be mitigated Encrypt the communication, ensure integrity Consider side channels

102 Securing NFC Systems Personal protection Put your card in sleeves Cut the antenna Building a product? Don t use known insecure systems If you re nailed on an insecure system: under certain conditions, vulnerabilities can be mitigated Encrypt the communication, ensure integrity Consider side channels Consider replay and relay attacks

103 Securing NFC Systems Personal protection Put your card in sleeves Cut the antenna Building a product? Don t use known insecure systems If you re nailed on an insecure system: under certain conditions, vulnerabilities can be mitigated Encrypt the communication, ensure integrity Consider side channels Consider replay and relay attacks Identify sensible data and require authentication/authorization for access, write protection

104 Securing NFC Systems Personal protection Put your card in sleeves Cut the antenna Building a product? Don t use known insecure systems If you re nailed on an insecure system: under certain conditions, vulnerabilities can be mitigated Encrypt the communication, ensure integrity Consider side channels Consider replay and relay attacks Identify sensible data and require authentication/authorization for access, write protection Don t rely on availability: tags can be destroyed or replaced Tags can be moved: don t believe that someone scans the tag where you placed it.

105 Securing NFC Systems Personal protection Put your card in sleeves Cut the antenna Building a product? Don t use known insecure systems If you re nailed on an insecure system: under certain conditions, vulnerabilities can be mitigated Encrypt the communication, ensure integrity Consider side channels Consider replay and relay attacks Identify sensible data and require authentication/authorization for access, write protection Don t rely on availability: tags can be destroyed or replaced Tags can be moved: don t believe that someone scans the tag where you placed it. Transmissions can be sniffed up to 10m away Communication can possibly be initiated at bigger ranges, than just some cm - consider at least 1,5m

106 Securing NFC Systems Personal protection Put your card in sleeves Cut the antenna Building a product? Don t use known insecure systems If you re nailed on an insecure system: under certain conditions, vulnerabilities can be mitigated Encrypt the communication, ensure integrity Consider side channels Consider replay and relay attacks Identify sensible data and require authentication/authorization for access, write protection Don t rely on availability: tags can be destroyed or replaced Tags can be moved: don t believe that someone scans the tag where you placed it. Transmissions can be sniffed up to 10m away Communication can possibly be initiated at bigger ranges, than just some cm - consider at least 1,5m Monitor the usage, e.g. one tag used at the same time in different locations.

107 NFC Hacking - Android Android Devices Android Framework: the android.nfc.* API offers interesting possibilities. NfcAdapter, NfcManager, NdefMessage, NdefRecord. connectivity/nfc/index.html Supports SO A, B, , NDEF, Mifare Classic+Ultralight and few other systems. Communication with smartcards, reading/writing NDEF tags etc.

108 NFC Hacking - Android Android Devices Android Framework: the android.nfc.* API offers interesting possibilities. NfcAdapter, NfcManager, NdefMessage, NdefRecord. connectivity/nfc/index.html Supports SO A, B, , NDEF, Mifare Classic+Ultralight and few other systems. Communication with smartcards, reading/writing NDEF tags etc. But: no proprietary systems, no low-level access, restricted card simulation, restricted timing control Several 100EUR. Possibly a bit expensive, if you don t need a new phone/tablet.

109 NFC Hacking - Android Apps NXP NFC TagInfo: apps/details?id=com.nxp.taginfolite NXP TagWriter: details?id=com.nxp.nfc.tagwriter NFC TagInfo: details?id=at.mroland.android.apps.nfctaginfo Banking Card Reader NFC (EMV): com.github.devnied.emvnfccard... and its API: https: //github.com/devnied/emv-nfc-paycard-enrollment CardTest: details?id=com.samj.cardtest

110 NFC Hacking - NFC Readers NFC Readers Tikitag, OpenPCD libnfc: Live RFID Hacking System: Price: <50EUR Same drawbacks as above

111 NFC Hacking - NFC Readers NFC Readers Tikitag, OpenPCD libnfc: Live RFID Hacking System: Price: <50EUR Same drawbacks as above Proxmark3 SDR-based, can principally support very much in 13,56MHz and kHz. FPGA: precise timing, for attacks like MIFARE breaking. Expensive: EUR a bit hacky

112 Questions? Web: Mail: