CISCO ROUTER HACKING -3

breaking the password

Now that you have acquired the password file, you have to break it so you can access the router again. To do this,
you can run a program like John the Ripper or something on the password file, and you may break it.

This is the easiest way, and the way i would recommend. Another way would be to try and decrypt it. For this you
will need some decryption software, a lot a patience, and some of the decryption sequences.

Here is a sequence for decrypting a cisco password, you have to compile this in linux:

#include

#include

char xlat[] = {
0x64, 0x73, 0x66, 0x64, 0x3b, 0x6b, 0x66, 0x6f,
0x41, 0x2c, 0x2e, 0x69, 0x79, 0x65, 0x77, 0x72,
0x6b, 0x6c, 0x64, 0x4a, 0x4b, 0x44
};

char pw_str1[] = "password 7 ";
char pw_str2[] = "enable-password 7 ";

char *pname; cdecrypt(enc_pw, dec_pw) char *enc_pw;
char *dec_pw;
{
unsigned int seed, i, val = 0;

if(strlen(enc_pw) & 1)
return(-1);

seed = (enc_pw[0] - '0') * 10 + enc_pw[1] - '0';

if (seed > 15 || !isdigit(enc_pw[0]) || !isdigit(enc_pw[1]))
return(-1);

for (i = 2 ; i <= strlen(enc_pw); i++) {
if(i !=2 && !(i & 1)) {
dec_pw[i / 2 - 2] = val ^ xlat[seed++];
val = 0;
}

val *= 16;

if(isdigit(enc_pw[i] = toupper(enc_pw[i]))) {
val += enc_pw[i] - '0';
continue;
}

if(enc_pw[i] >= 'A' && enc_pw[i] <= 'F') {
val += enc_pw[i] - 'A' + 10;
continue;
}

if(strlen(enc_pw) != i)
return(-1);
}

dec_pw[++i / 2] = 0;

return(0);
}

usage()
{
fprintf(stdout, "Usage: %s -p \n", pname);

fprintf(stdout, " %s

\n", pname);

return(0);
} main(argc,argv) int argc;
char **argv;

{
FILE *in = stdin, *out = stdout;
char line[257];
char passwd[65];
unsigned int i, pw_pos;

pname = argv[0];

if(argc > 1)
{
if(argc > 3) {
usage();
exit(1);
}

if(argv[1][0] == '-')
{
switch(argv[1][1]) {
case 'h':
usage();
break;

case 'p':
if(cdecrypt(argv[2], passwd)) {
fprintf(stderr, "Error.\n");
exit(1);
}
fprintf(stdout, "password: %s\n", passwd);
break;

default:
fprintf(stderr, "%s: unknow option.", pname);
}

return(0);
}

if((in = fopen(argv[1], "rt")) == NULL)
exit(1);
if(argc > 2)
if((out = fopen(argv[2], "wt")) == NULL)
exit(1);
}

while(1) {
for(i = 0; i < 256; i++) {
if((line[i] = fgetc(in)) == EOF) {

if(i)
break;

fclose(in);
fclose(out);
return(0);
}
if(line[i] == '\r')
i--;

if(line[i] == '\n')
break;
}
pw_pos = 0;
line[i] = 0;

if(!strncmp(line, pw_str1, strlen(pw_str1)))
pw_pos = strlen(pw_str1);

if(!strncmp(line, pw_str2, strlen(pw_str2)))
pw_pos = strlen(pw_str2);

if(!pw_pos) {
fprintf(stdout, "%s\n", line);
continue;
}

if(cdecrypt(&line[pw_pos], passwd)) {
fprintf(stderr, "Error.\n");
exit(1);
}
else {
if(pw_pos == strlen(pw_str1))
fprintf(out, "%s", pw_str1);
else
fprintf(out, "%s", pw_str2);

fprintf(out, "%s\n", passwd);
}
}
}

If you do not have Linux, then the only way to break the password is to run a dictionary or brute-force attack on
the file with John the Ripper or another password-cracker.