SUGGESTED FIX:

Issue: https://github.com/Proxmark/proxmark3/issues/35
Forum:  http://www.proxmark.org/forum/viewtopic.php?pid=7883#p7883

Where "hf mf csetuid"  empties the rest of the block0 bytes.
This fix loads the old block0 and replaces the uid+sak+ataq bytes only.

diff --git a/client/mifarehost.c b/client/mifarehost.c
index d025918d9130aac580d0b564e32082243cdfa526..e62d6260dcc758881cd1ae43b1bdb88c117fc281 100644 (file)
--- a/client/mifarehost.c
+++ b/client/mifarehost.c
@@ -232,14 +232,27 @@ int mfEmlSetMem(uint8_t *data, int blockNum, int blocksCount) {
 // "MAGIC" CARD\r
 \r
 int mfCSetUID(uint8_t *uid, uint8_t *oldUID, bool wantWipe) {\r
+       \r
+       uint8_t oldblock0[16] = {0x00};\r
        uint8_t block0[16] = {0x00};\r
        memcpy(block0, uid, 4); \r
        block0[4] = block0[0]^block0[1]^block0[2]^block0[3]; // Mifare UID BCC\r
        // mifare classic SAK(byte 5) and ATQA(byte 6 and 7)\r
-       block0[5] = 0x08;\r
-       block0[6] = 0x04;\r
-       block0[7] = 0x00;\r
+       //block0[5] = 0x08;\r
+       //block0[6] = 0x04;\r
+       //block0[7] = 0x00;\r
+       \r
+       block0[5] = 0x01;  //sak\r
+       block0[6] = 0x01;\r
+       block0[7] = 0x0f;\r
        \r
+       int old = mfCGetBlock(0, oldblock0, CSETBLOCK_SINGLE_OPER);\r
+       if ( old == 0) {\r
+               memcpy(block0+8, oldblock0+8, 8);\r
+               PrintAndLog("block 0:  %s", sprint_hex(block0,16));\r
+       } else {\r
+               PrintAndLog("Couldn't get olddata. Will write over the last bytes of Block 0.");\r
+       }\r
        return mfCSetBlock(0, block0, oldUID, wantWipe, CSETBLOCK_SINGLE_OPER);\r
 }\r
 \r
@@ -253,8 +266,10 @@ int mfCSetBlock(uint8_t blockNo, uint8_t *data, uint8_t *uid, bool wantWipe, uin
   UsbCommand resp;\r
        if (WaitForResponseTimeout(CMD_ACK,&resp,1500)) {\r
                isOK  = resp.arg[0] & 0xff;\r
-               if (uid != NULL) memcpy(uid, resp.d.asBytes, 4);\r
-               if (!isOK) return 2;\r
+               if (uid != NULL) \r
+                       memcpy(uid, resp.d.asBytes, 4);\r
+               if (!isOK) \r
+                       return 2;\r
        } else {\r
                PrintAndLog("Command execute timeout");\r
                return 1;\r
@@ -323,13 +338,16 @@ int isBlockTrailer(int blockN) {
 \r
 int loadTraceCard(uint8_t *tuid) {\r
        FILE * f;\r
-       char buf[64];\r
-       uint8_t buf8[64];\r
+       char buf[64] = {0x00};\r
+       uint8_t buf8[64] = {0x00};\r
        int i, blockNum;\r
        \r
-       if (!isTraceCardEmpty()) saveTraceCard();\r
+       if (!isTraceCardEmpty()) \r
+               saveTraceCard();\r
+               \r
        memset(traceCard, 0x00, 4096);\r
        memcpy(traceCard, tuid + 3, 4);\r
+\r
        FillFileNameByUID(traceFileName, tuid, ".eml", 7);\r
 \r
        f = fopen(traceFileName, "r");\r
@@ -380,10 +398,14 @@ int saveTraceCard(void) {
 \r
 int mfTraceInit(uint8_t *tuid, uint8_t *atqa, uint8_t sak, bool wantSaveToEmlFile) {\r
 \r
-       if (traceCrypto1) crypto1_destroy(traceCrypto1);\r
+       if (traceCrypto1) \r
+               crypto1_destroy(traceCrypto1);\r
+\r
        traceCrypto1 = NULL;\r
 \r
-       if (wantSaveToEmlFile) loadTraceCard(tuid);\r
+       if (wantSaveToEmlFile) \r
+               loadTraceCard(tuid);\r
+               \r
        traceCard[4] = traceCard[0] ^ traceCard[1] ^ traceCard[2] ^ traceCard[3];\r
        traceCard[5] = sak;\r
        memcpy(&traceCard[6], atqa, 2);\r