|
| 1 | +#if 0 |
| 2 | +gcc -Wall -W -ansi -pedantic -O2 cisco7crack.c -o cisco7crack || exit 1 |
| 3 | +echo successfully compiled |
| 4 | +exit |
| 5 | +#endif /* Compile with: sh ./cisco7crack.c */ |
| 6 | + |
| 7 | +/* CISCO7CRACK.C ver. 2.3.4 - San Oct 19, 2002 |
| 8 | + * (C) 2002 by Davide Madrisan <[email protected]> |
| 9 | + * |
| 10 | + * This program is free software; you can redistribute it and/or modify it under |
| 11 | + * the terms of the GNU General Public License as published by the Free Software |
| 12 | + * Foundation; either version 2 of the License, or (at your option) any later |
| 13 | + * version. |
| 14 | + * |
| 15 | + * This program is distributed in the hope that it will be useful, but WITHOUT |
| 16 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS |
| 17 | + * FOR A PARTICULAR PURPOSE. |
| 18 | + * See the GNU General Public License for more details. |
| 19 | + * |
| 20 | + * Enjoy cracking the Cisco pesky passwords... |
| 21 | + * (like 'enable password 7 104D000A0618') |
| 22 | + * |
| 23 | + * Passwords can be up to twenty-five mixed-case characters. |
| 24 | + * In the "encrypted" representation, the first two bytes of the long string are |
| 25 | + * a random decimal offset between 0 and 15 into a magic block of characters, |
| 26 | + * and the remaining bytes are ascii-hex representations of the password bytes |
| 27 | + * xored against the character-block bytes from the given offset on down, |
| 28 | + * modulus the character-block length. |
| 29 | + * The character block is "dsfd;kfoA,.iyewrkldJKDHSUB". |
| 30 | + * |
| 31 | + * compiled successfully with gcc version 2.95.3 |
| 32 | + * (gcc -Wall -W -Wstrict-prototypes -ansi -pedantic -O2 \ |
| 33 | + * -o cisco7crack cisco7crack.c) |
| 34 | + * |
| 35 | + * indented with the gnu-indent tool |
| 36 | + * (indent -kr -i5 -nut cisco7crack.c) |
| 37 | + */ |
| 38 | + |
| 39 | +#include <ctype.h> |
| 40 | +#include <fcntl.h> |
| 41 | +#include <stdarg.h> |
| 42 | +#include <stdio.h> |
| 43 | +#include <stdlib.h> |
| 44 | +#include <string.h> |
| 45 | +#include <time.h> |
| 46 | +#include <unistd.h> |
| 47 | +#include "cisco7crack.h" |
| 48 | + |
| 49 | + |
| 50 | +void usage(void) |
| 51 | +{ |
| 52 | + static const char *usage_msg[] = { |
| 53 | + "*** " PROGRAM " " VERSION, |
| 54 | + " copyright (c) 2002 by " AUTHOR, |
| 55 | + " the GNU GPLv2 applies to this program and code", |
| 56 | + "", |
| 57 | + "usage:", |
| 58 | + " " PROGRAM " [-q] -c [-{a|#<0..15>}] <plaintext>", |
| 59 | + " " PROGRAM " [-q] [-d] <ciphertext>", |
| 60 | + " " PROGRAM " [-h]", |
| 61 | + "", |
| 62 | + "flags: means:", |
| 63 | + " -c crypt <plaintext>", |
| 64 | + " -a display all the ways to crypt <plaintext>", |
| 65 | + " -#<n> display the n-th way to crypt <plaintext>", |
| 66 | + " -d decrypt <ciphertext> (default option)", |
| 67 | + " -q cause " PROGRAM " to be really quiet", |
| 68 | + " -h display this brief usage summary", |
| 69 | + "", |
| 70 | + "examples are:", |
| 71 | + " " PROGRAM " -c#3 '@l1c3&b0b'", |
| 72 | + " " PROGRAM " -c#3 -q n0v3rb0s3", |
| 73 | + " " PROGRAM " 082F1C5A1A490D43000F5E033F78373B", |
| 74 | + "", |
| 75 | + " a=`" PROGRAM " -cq b@shscr1pt` # (bash shell)", |
| 76 | + " [ $? -eq 0 ] && echo \"crypt: $a\" || echo \"error!\"", |
| 77 | + "", |
| 78 | + "enjoy cracking the Cisco IOS pesky passwords...", |
| 79 | + "for bugs and suggestions, please contact me by e-mail", |
| 80 | + "" |
| 81 | + }; |
| 82 | + unsigned int i, u_lines = sizeof(usage_msg) / sizeof(*usage_msg); |
| 83 | + |
| 84 | + for (i = 0; i < u_lines; i++) |
| 85 | + fprintf(stderr, "%s\n", usage_msg[i]); |
| 86 | + exit(ERR_USAGE); |
| 87 | +} |
| 88 | + |
| 89 | +int decrypt_str(const char *passwd) |
| 90 | +{ |
| 91 | + char crypted[MAX_ENCRYPTED_LEN], *ptr1, *ptr2; |
| 92 | + unsigned int arglen, cryptlen, pairs, i, index = 0; |
| 93 | + |
| 94 | + if ((arglen = strlen(passwd)) > MAX_ENCRYPTED_LEN - 1) |
| 95 | + cfprintf(stderr, "WARNING: crypted string too long! " |
| 96 | + "(last %d chars flushed)\n", |
| 97 | + arglen - MAX_ENCRYPTED_LEN + 1); |
| 98 | + /* 'strncpy' used to avoid buffer overflow... */ |
| 99 | + strncpy(crypted, passwd, MAX_ENCRYPTED_LEN); |
| 100 | + /* even if strlen(passwd) > MAXSTRLEN, |
| 101 | + * crypt[] must be a null terminated string |
| 102 | + */ |
| 103 | + crypted[MAX_ENCRYPTED_LEN - 1] = 0; |
| 104 | + pairs = (cryptlen = strlen(crypted)) / 2; |
| 105 | + |
| 106 | + cfprintf(stdout, "%-17s: %s\n", "Encrypted string", crypted); |
| 107 | + cfprintf(stdout, "%-17s: ", "Plain string"); |
| 108 | + |
| 109 | + ptr1 = strchr(dec, crypted[0]); |
| 110 | + ptr2 = strchr(dec, crypted[1]); |
| 111 | + if (!ptr1 || !ptr2) { |
| 112 | + /* 'crypted' should begin with two decimal digits */ |
| 113 | + cfprintf(stderr, |
| 114 | + "ERROR: illegal 1st pair of digits in crypted string\n"); |
| 115 | + return ERR_INPUT_ILLEGAL_CHAR; |
| 116 | + } |
| 117 | + index = (ptr1 - dec) * 10 + (ptr2 - dec); |
| 118 | + |
| 119 | + for (i = 1; i < pairs; i++) { |
| 120 | + ptr1 = strchr(hex, crypted[i * 2]); |
| 121 | + ptr2 = strchr(hex, crypted[i * 2 + 1]); |
| 122 | + if (!ptr1 || !ptr2) { |
| 123 | + cfprintf(stderr, |
| 124 | + "[?] ERROR: bad pair of hex digits (pair: %d)\n", |
| 125 | + i + 1); |
| 126 | + return ERR_INPUT_ILLEGAL_CHAR; |
| 127 | + } |
| 128 | + printf("%c", |
| 129 | + (((ptr1 - hex) << 4) + (ptr2 - hex)) ^ magic[index++]); |
| 130 | + index %= magic_size; |
| 131 | + } |
| 132 | + printf("\n"); |
| 133 | + |
| 134 | + /* encrypted strings with odd number of digits are illegal */ |
| 135 | + if (cryptlen % 2) { |
| 136 | + cfprintf(stderr, |
| 137 | + "WARNING: input truncated! (odd number of letters)\n"); |
| 138 | + return ERR_INPUT_ODD_DIGITS; |
| 139 | + } |
| 140 | + return ERR_NONE; |
| 141 | +} |
| 142 | + |
| 143 | +int crypt_str(const char *str2crypt, int xor_offset) |
| 144 | +{ |
| 145 | + register unsigned int i, j; |
| 146 | + unsigned int first, last, index, str2cryptlen = strlen(str2crypt); |
| 147 | + bool too_long_input; |
| 148 | + |
| 149 | + if ((too_long_input = (str2cryptlen > MAX_PLAIN_LEN))) { |
| 150 | + str2cryptlen = min(str2cryptlen, MAX_PLAIN_LEN); |
| 151 | + cfprintf(stderr, "WARNING: overly long password truncated after " |
| 152 | + "%d characters\n", MAX_PLAIN_LEN); |
| 153 | + cfprintf(stdout, "%-17s: ", "Plain string"); |
| 154 | + for (i = 0; i < MAX_PLAIN_LEN; i++) |
| 155 | + printf("%c", str2crypt[i]); |
| 156 | + printf("\n"); |
| 157 | + } else |
| 158 | + cfprintf(stdout, "%-17s: %s\n", "Plain string", str2crypt); |
| 159 | + |
| 160 | + /* user ask for a random offset in magic[] */ |
| 161 | + if (xor_offset == OFFSET_RANDOM) |
| 162 | + first = last = get_entropy(); |
| 163 | + /* list all the crypted strings that IOS can generate */ |
| 164 | + else if (xor_offset == OFFSET_ALL) { |
| 165 | + first = 0; |
| 166 | + last = MAX_XOR_OFFSET; |
| 167 | + } |
| 168 | + /* the user has specified an initial offset in magic[] */ |
| 169 | + else |
| 170 | + first = last = xor_offset; |
| 171 | + |
| 172 | + cfprintf(stdout, "%-17s: ", "Encrypted string"); |
| 173 | + |
| 174 | + /* from 'first' to 'last' way to crypt the 'str2crypt' */ |
| 175 | + for (j = first; j <= last; j++) { |
| 176 | + /* mod just to make the code more robust */ |
| 177 | + index = j % magic_size; |
| 178 | + if (j != first) |
| 179 | + cfprintf(stdout, "%-19s", ""); |
| 180 | + printf("%02d", index); |
| 181 | + /* from first to last char allowed in 'str2crypt' */ |
| 182 | + for (i = 0; i < str2cryptlen; i++) { |
| 183 | + printf("%02X", str2crypt[i] ^ magic[index++]); |
| 184 | + index %= magic_size; /* mod : same as above */ |
| 185 | + } |
| 186 | + printf("\n"); |
| 187 | + } |
| 188 | + return too_long_input ? ERR_INPUT_TOO_LONG : ERR_NONE; |
| 189 | +} |
| 190 | + |
| 191 | +unsigned int get_entropy(void) |
| 192 | +{ |
| 193 | +#ifdef LINUX |
| 194 | + int devurandom; |
| 195 | +#endif |
| 196 | + unsigned int entropy; |
| 197 | + |
| 198 | +#ifdef LINUX |
| 199 | + /* if your Linux system does not have /dev/random created already, |
| 200 | + it can be created with the following commands: |
| 201 | + mknod -m 644 /dev/urandom c 1 9 |
| 202 | + chown root:root /dev/urandom |
| 203 | + */ |
| 204 | + devurandom = open("/dev/urandom", O_RDONLY | O_NONBLOCK); |
| 205 | + if (devurandom != -1) { |
| 206 | + read(devurandom, &entropy, sizeof(entropy)); |
| 207 | + close(devurandom); |
| 208 | + } else { |
| 209 | + /* rand() function call is not a very good source of randomness */ |
| 210 | + cfprintf |
| 211 | + (stderr, |
| 212 | + "WARNING: couldn't open /dev/urandom, falling back to rand()\n"); |
| 213 | +#endif |
| 214 | + srand((unsigned int) time(NULL)); |
| 215 | + /* to use higher-order bits of pseudo-random number... */ |
| 216 | + entropy = |
| 217 | + (unsigned int) (1. * rand() * MAX_XOR_OFFSET / RAND_MAX); |
| 218 | +#ifdef LINUX |
| 219 | + } |
| 220 | +#endif |
| 221 | + return entropy; |
| 222 | +} |
| 223 | + |
| 224 | +void cfprintf(FILE * stream, const char *fmt, ...) |
| 225 | +{ /* conditional printf */ |
| 226 | + va_list argptr; |
| 227 | + int cnt; |
| 228 | + |
| 229 | + if (opt.quiet) /* no output message required */ |
| 230 | + return; |
| 231 | + |
| 232 | + va_start(argptr, fmt); |
| 233 | + fflush(stdout); /* to avoid some visualisation problems */ |
| 234 | + cnt = vfprintf(stream, fmt, argptr); |
| 235 | + va_end(argptr); |
| 236 | +} |
| 237 | + |
| 238 | +#ifdef HEX_LOWER_SUPPORT |
| 239 | +char *strtoupper(char *str) |
| 240 | +{ |
| 241 | + char *saved = str; |
| 242 | + |
| 243 | + while ((*str++ = toupper(*str))); |
| 244 | + return saved; |
| 245 | +} |
| 246 | +#endif |
| 247 | + |
| 248 | +int main(int argc, char **argv) |
| 249 | +{ |
| 250 | + unsigned int c; |
| 251 | + opt.crypt = opt.decrypt = opt.quiet = false; |
| 252 | + opt.xor_offset = OFFSET_RANDOM; /* random initial offset in magic[] */ |
| 253 | + |
| 254 | + /* command line input parser */ |
| 255 | + while (--argc > 0 && **++argv == '-') { |
| 256 | + /* catch user errors like : cisco7crack - -c#3 @l1c3 */ |
| 257 | + if (!*(*argv + 1)) |
| 258 | + usage(); |
| 259 | + while ((c = *++*argv)) /* process multiple options like -sc#8 */ |
| 260 | + switch (c) { |
| 261 | + case 'c': /* crypt */ |
| 262 | + if (opt.decrypt) /* decrypt option already selected */ |
| 263 | + usage(); |
| 264 | + opt.crypt = true; |
| 265 | + break; |
| 266 | + case 'a': /* display all the ways to crypt the input passwd */ |
| 267 | + if (opt.decrypt || opt.xor_offset != OFFSET_RANDOM) |
| 268 | + usage(); |
| 269 | + opt.xor_offset = OFFSET_ALL; /* all the offsets */ |
| 270 | + break; |
| 271 | + case '#': /* user-defined initial offset in magic[] */ |
| 272 | + if (opt.decrypt || opt.xor_offset != OFFSET_RANDOM) |
| 273 | + usage(); |
| 274 | + opt.xor_offset = atoi(*argv + 1); |
| 275 | + if (opt.xor_offset < 0 |
| 276 | + || opt.xor_offset > MAX_XOR_OFFSET) |
| 277 | + usage(); |
| 278 | + /* skip digits already parsed by atoi() */ |
| 279 | + while (isdigit(*(++*argv + 1))); |
| 280 | + break; |
| 281 | + case 'd': /* decrypt */ |
| 282 | + if (opt.crypt) |
| 283 | + usage(); |
| 284 | + opt.decrypt = true; |
| 285 | + break; |
| 286 | + case 'q': /* minimize the program output */ |
| 287 | + opt.quiet = true; |
| 288 | + break; |
| 289 | + case 'h': /* help */ |
| 290 | + default: /* unknown option */ |
| 291 | + usage(); |
| 292 | + } |
| 293 | + } |
| 294 | + |
| 295 | + if (argc != 1) |
| 296 | + usage(); /* usage error (too many arguments entered) */ |
| 297 | + |
| 298 | + if (!opt.crypt && !opt.decrypt) { /* make decrypt the default actions */ |
| 299 | + if (opt.xor_offset != OFFSET_RANDOM) |
| 300 | + usage(); |
| 301 | + opt.decrypt = true; |
| 302 | + } |
| 303 | + |
| 304 | + return opt.decrypt ? |
| 305 | +#ifdef HEX_LOWER_SUPPORT |
| 306 | + decrypt_str(strtoupper(*argv)) |
| 307 | +#else |
| 308 | + decrypt_str(*argv) |
| 309 | +#endif |
| 310 | + : crypt_str(*argv, opt.xor_offset); |
| 311 | +} |
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