S´ ecurit´ e des cartes ` a puce:

Introduction Background Towards a high level model of attacks Using the model Sécurité des cartes à puce: des attaques physiques aux protections logicielles P. Berthomé, K. Heydemann, X. Kauffmann-Tourkestansky, J.-F. Lalande Journée Risques - 5 juin 2012 Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Introduction Context: Smart card are subject to physical attacks Security is of main importance for the card industry Adding security countermeasures is not so obvious. . . is an expensive and time consuming process Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Introduction - physical attacks Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Introduction - physical attacks See this - Do this Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Introduction - attacks Two types of attacks to consider: Side channel attacks Fault injection attacks Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Authentication for smart card Buffers Terminal Vcc 1 2 3 CLK 4 5 6 IO B U F 1 CPU BUS 7 8 9 B U F 2 RAM ROM EPROM Circuit Memories SMART CARD Internals - Information Flow Smart Card Internals Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Authentication for smart card Buffers 1234 Vcc 1 2 3 CLK 4 5 6 IO B U F 1 CPU BUS 7 8 9 B U F 2 RAM ROM EPROM 0000 Circuit Memories SMART CARD Internals - Information Flow Terminal Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Authentication for smart card Buffers 1234 1234 Vcc 1 2 3 CLK 4 5 6 IO B U F 1 CPU BUS 7 8 9 B U F 2 RAM ROM EPROM Circuit Memories SMART CARD Internals - Information Flow Sent to card’s circuit Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Authentication for smart card Buffers 1234 Terminal Vcc 1 2 3 CLK 4 5 6 IO 1 2 3 4 CPU BUS 7 8 9 B U F 2 RAM ROM EPROM Circuit Memories SMART CARD Internals - Information Flow ROM code tells CPU to load value in a RAM buffer Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Authentication for smart card Buffers Terminal Vcc 1 2 3 CLK 4 5 6 IO 1 R 2 E 3 G 1 4 CPU BUS 7 8 9 0 0 0 0 RAM ROM EPROM 0000 Circuit Memories SMART CARD Internals - Information Flow ROM code tells CPU to load key in a RAM buffer Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Authentication for smart card Buffers Terminal Vcc 1 2 3 CLK 4 5 6 IO 1 2 3 4 CPU BUS 7 8 9 0 0 0 0 RAM ROM EPROM Circuit Memories SMART CARD Internals - Information Flow ROM function compares buffers Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Example of attacks Let us consider such an authentication code: uint user tries = 0; // initialization of the number of tries for this session uint max tries = 3; // max number of tries while (...) /∗ card life cycle: ∗/ { incr tries(user tries); res = get pin from terminal(); // receives 1234 pin = read secret pin(); // read real pin: 0000 if (compare(res, pin)) { dec tries(user tries); } if (user tries < max tries) { everything is fine(); } else { killcard(); } } Simplified authentication code with pin check Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Example of attacks Let us consider such an authentication code: uint user tries = 0; // initialization of the number of tries for this session uint max tries = 3; // max number of tries while (...) /∗ card life cycle: ∗/ { incr tries(user tries); → NOP ... NOP res = get pin from terminal(); // receives 1234 pin = read secret pin(); // read real pin: 0000 if (compare(res, pin)) { dec tries(user tries); } if (user tries < max tries) // always true { everything is fine(); } else { killcard(); } } Simplified authentication code with pin check Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Example of attacks Let us consider such an authentication code: uint user tries = 0; // initialization of the number of tries for this session uint max tries = 3; // max number of tries while (...) /∗ card life cycle: ∗/ { incr tries(user tries); res = get pin from terminal(); // receives 1234 pin = read secret pin(); // read real pin: 0000 if (compare(res, pin)) { dec tries(user tries); } if (user tries < max tries) { everything is fine(); } else { killcard(); } → NOP ... NOP } Simplified authentication code with pin check Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Example of attacks Let us consider such an authentication code: uint user tries = 0; // initialization of the number of tries for this session uint max tries = 3; // max number of tries while (...) /∗ card life cycle: ∗/ { incr tries(user tries); res = get pin from terminal(); // receives 1234 pin = read secret pin(); // read real pin: 0000 pin ← ”1234” if (compare(res, pin)) // always true { dec tries(user tries); } if (user tries < max tries) { everything is fine(); } else { killcard(); } } Simplified authentication code with pin check Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Attack vectors Buffers Terminal Vcc 1 2 3 CLK 4 5 6 IO B U F 1 CPU BUS 7 8 9 B U F 2 RAM ROM EPROM Circuit Memories SMART CARD Internals Example: attack on card bus! What about security? Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Security problems Several questions appear: How to explain low level attacks at source code level? How to identifiy harmfull attacks? How to implement countermeasures? How to evalute the efficiency of countermeasures? Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Physical attacks Authentication for smart card Security problems Several questions appear: How to explain low level attacks at source code level? How to identifiy harmfull attacks? How to implement countermeasures? How to evalute the efficiency of countermeasures? Two goals Create a high level model of attacks (developer level) Provide a security test methodology Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Outline 1 Introduction 2 Background Smart Card Development Process Attack hypothesis 3 Towards a high level model of attacks 4 Using the model Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Smart Card Development Process Software SOFTWARE SPECIFICATIONS SOFTWARE DEVELOPMENT EMBED SOFTWARE ON CHIP HARDWARE SECURITY TEST Hardware Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce SOFTWARE TEST CARD READY Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Smart Card Development Process SOFTWARE SPECIFICATIONS SOFTWARE DEVELOPMENT EMBED SOFTWARE ON CHIP HARDWARE SECURITY TEST Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce SOFTWARE TEST CARD READY Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Smart Card Development Process SOFTWARE SPECIFICATIONS SOFTWARE DEVELOPMENT EMBED SOFTWARE ON CHIP HARDWARE SECURITY TEST Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce SOFTWARE TEST CARD READY Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Smart Card Development Process SOFTWARE SPECIFICATIONS SOFTWARE DEVELOPMENT EMBED SOFTWARE ON CHIP HARDWARE SECURITY TEST Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce SOFTWARE TEST CARD READY Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Smart Card Development Process SOFTWARE SPECIFICATIONS SOFTWARE DEVELOPMENT EMBED SOFTWARE ON CHIP HARDWARE SECURITY TEST Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce SOFTWARE TEST CARD READY Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Smart Card Development Process SOFTWARE SPECIFICATIONS SOFTWARE DEVELOPMENT EMBED SOFTWARE ON CHIP HARDWARE SECURITY TEST Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce SOFTWARE TEST CARD READY Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Smart Card Development Process SOFTWARE SPECIFICATIONS SOFTWARE DEVELOPMENT EMBED SOFTWARE ON CHIP HARDWARE SECURITY TEST Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce SOFTWARE TEST CARD READY Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Smart Card Development Process SOFTWARE SPECIFICATIONS SOFTWARE DEVELOPMENT EMBED SOFTWARE ON CHIP HARDWARE SECURITY TEST Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce SOFTWARE TEST CARD READY Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Smart Card Development Process SOFTWARE SPECIFICATIONS SOFTWARE DEVELOPMENT EMBED SOFTWARE ON CHIP HARDWARE SECURITY TEST Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce SOFTWARE TEST Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Smart Card Development Process SOFTWARE SPECIFICATIONS SOFTWARE DEVELOPMENT EMBED SOFTWARE ON CHIP HARDWARE SECURITY TEST SOFTWARE TEST CARD READY Objectives: Simulate hardware attacks at software level Move some security hardware tests to software level Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Smart Card Development Process SOFTWARE SPECIFICATIONS EMBED SOFTWARE ON CHIP SOFTWARE DEVELOPMENT SOFTWARE TEST HARDWARE SECURITY TEST CARD READY Objectives: Simulate hardware attacks at software level Move some security hardware tests to software level Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Smart Card Development Process SOFTWARE SPECIFICATIONS EMBED SOFTWARE ON CHIP SOFTWARE DEVELOPMENT SOFTWARE TEST HARDWARE SECURITY TEST CARD READY Objectives: Simulate hardware attacks at software level Move some security hardware tests to software level Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Attack hypothesis Attacks on smart cards in Common Criteria [1]: modifying a value read from memory; changing the quality of random numbers generated; modifying the program flow. Attack model in the literature [2]: precise bit error; precise byte error; unknown byte error; unknown error. Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Attack hypothesis One or several consecutive bytes are overwritten: bytes encode operations that are opcodes or operands for example, one opcode and its operands may be deleted: Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Smart Card Development Process Attack hypothesis Hypothesis and difficulties Hypothesis: One attack during one execution One attack on one or several consecutive bytes Difficulties: What happens when an opcode is deleted? What happens when an operand is deleted? What happens when an opcode is replaced? Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Outline 1 2 3 4 Introduction Physical attacks Authentication for smart card Background Smart Card Development Process Attack hypothesis Towards a high level model of attacks Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Using the model Experimental setup Experimental results Results on smart card codes Conclusion Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Example of high level model of a low level consequence compilation + deployment C code execution Assembly Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Smart card Chip Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Example of high level model of a low level consequence compilation + deployment C code execution Assembly Smart card Chip Attack Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Example of high level model of a low level consequence compilation + deployment C code execution Assembly Attack model Smart card Chip Attack impact Attack Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Example of high level model of a low level consequence compilation + deployment execution Assembly Attack model Berthomé - Heydemann - Kauffman - Lalande Smart card Chip Attack impact Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Example of high level model of a low level consequence compilation + deployment execution Smart card Chip Attack model Berthomé - Heydemann - Kauffman - Lalande Attack impact Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Example of high level model of a low level consequence compilation + deployment execution Smart card Chip Attack model Berthomé - Heydemann - Kauffman - Lalande Attack impact Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Example of high level model of a low level consequence compilation + deployment execution Smart card Chip Attack model Berthomé - Heydemann - Kauffman - Lalande Attack impact Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Flow shifting for opcode replacement Opcode X becomes opcode Y X arg1 arg2 ; → Y arg1 ; arg2 arg2 is viewed as an opcode and the instruction flow is shifted Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Flow shifting for opcode replacement Opcode X becomes opcode Y X arg1 arg2 ; → Y arg1 ; arg2 arg2 is viewed as an opcode and the instruction flow is shifted X arg1 arg2 ; → Y ; arg1 arg2 arg1 is viewed as an opcode. Depending on the number of bytes needed by arg1, arg2 is then either an operand or an opcode. The instruction flow has also shifted. Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Flow shifting for opcode replacement Opcode X becomes opcode Y X arg1 arg2 ; → Y arg1 ; arg2 arg2 is viewed as an opcode and the instruction flow is shifted X arg1 arg2 ; → Y ; arg1 arg2 arg1 is viewed as an opcode. Depending on the number of bytes needed by arg1, arg2 is then either an operand or an opcode. The instruction flow has also shifted. X arg1 arg2 ; → Y arg1 arg2 ; the instruction flow has not shifted. Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model But... shifted flows quickly recover Lemma: A shifted flow recovers to the normal flow in 1/p operations, with p the probability that a random byte is an opcode in the original flow. Using the 8051 assembly code, p = 0.64. The flow recovers in 1.56 steps... Are attacks always successful ? new opcodes may crash the program the original opcodes may suffer from missing opcodes Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Assembly attack consequences Let us take the following example: 1 2 3 4 5 6 7 8 c = u + 5; b = c < 10; if (b){ res = c + 1; } else{ res = 0; } mov r2,dpl // load the parameter in r2 mov a,#0x05 // put 5 into a add a,r2 // compute u + 5 in a mov c,a // store c into RAM from a clr c // clear the carry subb a,#0x0A // computes b i. e. c−10 jnc 00102$ // jumps to 102 // if carry is not set mov a, c // load c into a inc a // a++ i.e c + 1 mov r2,a // r2 stores a (res = c + 1) sjmp 00103$ // jump over else 00102$: mov r2,#0x00 // r2 stores 0 (res = 0) 00103$: mov dpl,r2 // push r2 on the stack Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Example 1: NOP insertion mov r2,dpl mov a,#0x05 add a,r2 mov c,a clr c subb a,#0x0A → NOP jnc 00102$ mov a, c inc a mov r2,a sjmp 00103$ 00102$: mov r2,#0x00 00103$: mov dpl,r2 Berthomé - Heydemann - Kauffman - Lalande 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 c = u + 5; b = c < 10; if (b){ → if(false) res = c + 1; } else{ res = 0; } Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Example 1: NOP insertion mov r2,dpl mov a,#0x05 add a,r2 mov c,a clr c subb a,#0x0A → NOP jnc 00102$ mov a, c inc a mov r2,a sjmp 00103$ 00102$: mov r2,#0x00 00103$: mov dpl,r2 Berthomé - Heydemann - Kauffman - Lalande 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 c = u + 5; b = c < 10; goto label; if (b){ res = c + 1; } else{ label : res = 0; } Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Example 2: NOP insertion (again !) mov r2,dpl mov a,#0x05 → NOP add a,r2 mov c,a clr c subb a,#0x0A jnc 00102$ mov a, c inc a mov r2,a sjmp 00103$ 00102$: mov r2,#0x00 00103$: mov dpl,r2 Berthomé - Heydemann - Kauffman - Lalande 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 c = u + 5;→ c = u+? b = c < 10; if (b){ res = c + 1; } else{ res = 0; } Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Example 2: NOP insertion (again !) mov r2,dpl mov a,#0x05 → NOP add a,r2 mov c,a clr c subb a,#0x0A jnc 00102$ mov a, c inc a mov r2,a sjmp 00103$ 00102$: mov r2,#0x00 00103$: mov dpl,r2 Berthomé - Heydemann - Kauffman - Lalande 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 c = attack(); b = c < 10; if (b){ res = c + 1; } else{ res = 0; } Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model Example 3: instruction override mov r2,dpl mov a,#0x05 add a,r2 mov c,a clr c subb a,#0x0A jnc 00102$ mov a, c inc a mov r2,a sjmp 00103$ 00102$: mov r2,#0x00 00103$: mov dpl,r2 → jmp 102 Berthomé - Heydemann - Kauffman - Lalande 1 2 3 1 4 2 5 3 6 4 7 5 8 6 9 7 10 8 11 9 12 10 13 14 15 c = u + 5; b = c < 10; if (b){ res = c + 1; } else{ label: res = 0; } goto label; Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Studying low level attacks consequences Flow shifting Assembly attack analysis Jump attack model High level attack model The examples show that the variables may be affected the flow control may be changed arbitrary jumps may be introduced The high level attack model proposed is based on: perturbating variables: a = attack(); introducing inconditional jumps: goto label; Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion Outline 1 Introduction 2 Background 3 Towards a high level model of attacks 4 Using the model Experimental setup Experimental results Results on smart card codes Conclusion Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion Principles of experiments Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion Principles of experiments Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion Principles of experiments Principles: Generate high-level attacks: new C source codes Test exhaustively the resulting programs How to classify attack effects ? Good: the execution gives the expected output Bad: the ouput is wrong or an error occured Crash: the program crashed Signal: a signal has been received (SIGSEGV) Killed: an infinite loop occured Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion Good candidates Candidates: Pure C programs with measurable input/output ⇒ SPEC 2006 benchmark suite Jump attacks stay into a function Bzip2: 107 functions, 8 643 C statements assembly code: 26 103 instructions Bzip2 Source code size (lines) Nb generated attacked codes Assembly code 26 103 3 531 954 High level C 8 643 117 802 n2 attacks for each bzip2 function of size n Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion Coverage Statistics Code size Simu. time Nb of BADs Uniq BADs ASM coverage ASM 26 103 2d 18h 273 129 2 326 100% C 8 643 8h 14 050 1245 21% gdb 8 643 2h 5 417 852 21% Statistics for simulated attacks on bzip2 Berthomé - Heydemann - Kauffman - Lalande Coverage of uniq bads Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion BZ2 compressBlock profile kill Destination line number 5561 good bad 5551 5541 5531 5521 5511 5501 5491 5481 5484 5494 5504 5514 5524 5534 5544 5554 Source line number Spatial classification of good/bad/kill attacks according to source/dest. lines, simulated in C against BZ2 compressBlock Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion BZ2 blockSort profile Destination line number 4156 kill good bad 4146 4136 4126 4116 4106 4096 4086 4087 4097 4107 4117 4127 4137 Source line number Spatial classification of good/bad/kill attacks according to source/destination lines, simulated in C against BZ2 blockSort Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce 4147 Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion Implementing countermeasures 4085 4086 4087 4088 4140 4141 4142 4143 4144 4145 4146 4147 4148 4149 4150 4151 Original code /∗∗ Countermeasure ∗∗/ /∗∗ kc(); = {perror(”KILLCARD”);exit(−1);} ∗∗/ int security = 48; ... security++; s−>origPtr = −1; if (security != 49) kc(); security++; for (i = 0; i < s−>nblock; i++) { if (security != 50+2∗i) kc(); security++; if (ptr[i] == 0) { s−>origPtr = i; break; }; if (security != 51+2∗i) kc(); security++; } if (security < 50) kc(); AssertH(s−>origPtr != −1, 1003); Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion Implementing countermeasures: before Destination line number 4156 kill good bad 4146 4136 4126 4116 4106 4096 4086 4087 4097 4107 4117 4127 Source line number BZ2 blockSort: before Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce 4137 4147 Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion Implementing countermeasures: after Destination line number 4156 kill good bad 4146 4136 4126 4116 4106 4096 4086 4087 4097 4107 4117 4127 Source line number BZ2 blockSort: after Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce 4137 4147 Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion Results for an sensitive function of a smart card killed bad good error killcard not_triggered Destination line number 270 250 230 210 190 170 150 130 110 90 90 110 130 150 170 190 210 230 250 270 Source line number Spatial classification for a sensitive function of a smart card code Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion Conclusion Problems How to model physical attacks at software level? How to inject jump attacks? How to classify the impact of attacks? Contributions Attack injection platform for C programs Experimental results on bzip2 and smart card codes Profiling of attacks Identification of weak points in functions Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce Introduction Background Towards a high level model of attacks Using the model Experimental setup Experimental results Results on smart card codes Conclusion Questions Common Criteria. Application of Attack Potential to Smartcards. Technical Report March, BSI, 2009. A. A. Sere, J. Iguchi-Cartigny, and J.-L. Lanet. Automatic detection of fault attack and countermeasures. In 4th Workshop on Embedded Systems Security, pages 1–7, New York city, New York state, USA, 2009. ACM Press. Berthomé - Heydemann - Kauffman - Lalande Sécurité des cartes à puce

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