How to hide from UNIX strings - obfuscate or hide a literal or constant?

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# 1  
Old 03-08-2014
How to hide from UNIX strings - obfuscate or hide a literal or constant?


I need to somehow pipe the password to a command and run some SQL, for example, something like echo $password | sqlplus -s system @query01.sql

To make it not so obvious, I decided to try out writing a small C program that basically just do echo $password. So now I just do x9.out | sqlplus -s system@query01.sql.

I understand it still is not a secure thing to do as someone can just run x9.out and knows the password. Anyway, the intent is to make is less obvious that I am echo'ing a password so I am more than happy with that for the time being as a start.

The very, very simple C program is a below:

$ cat x9.c
#include <stdio.h>

int main()
    char array[20] = "hello";


    return 0;
$ cc -o x9.out x9.c
$ ./x9.out
$ strings x9.out
l$ L

Unfortunately, as you can see if I do a strings of the x9.out file, it is quite obvious that the word hello stands out.

Can anyone please advise how I can somehow hide that word in the bushes Smilie?

For example, maybe I can do a printf of the ASCII values of the word so that if anyone do a strings of it, it shows number instead of words.

Finally, eventually, I would want to put something more into the code so that it will be an array that stores a list of username+password, so that if I do x9.out user01 it prints the password of user01, x9.out user02 prints the password of user02 and so on. It will probably be wise that it prompts for a username/password before it allows me to display the information.

BTW, it would be nice if I can put the whole "echo $password | sqlplus -s system" string into the C program so that I only do x9.out @query01.sql so it hides the username and password. I don't see how that they can be done, maybe one of the gurus can advice how to do that.

Anyway for now, I just want to know how to hide from UNIX strings :-)

Last edited by newbie_01; 03-08-2014 at 05:41 AM.. Reason: Adding more info
# 2  
Old 03-08-2014
How about read-protecting the pw for other users?
echo hello > pwfile
chmod 600 pwfile
sqlplus -s system@query01.sql < pwfile

# 3  
Old 03-08-2014
How about...
char array[20];

array[2] = 'l';
array[4] = 'o';
array[5] = (char)0;
array[1] = 'e';
array[3] = 'l';
array[0] = 'h';

Do that just immediately before you use it. Wipe it out immediately after use.
These 2 Users Gave Thanks to Perderabo For This Post:
# 4  
Old 03-08-2014
How about using shc - Script Compiler?

# 5  
Old 03-10-2014
Originally Posted by Perderabo
How about...
char array[20];

array[2] = 'l';
array[4] = 'o';
array[5] = (char)0;
array[1] = 'e';
array[3] = 'l';
array[0] = 'h';

Do that just immediately before you use it. Wipe it out immediately after use. Do you mean do a array[]="" after I do the print?
Hi Perderabo,

Thanks as usual to be the first responder.

I am more or less using the one that you suggested. What do you mean by wipe it out immediately?

BTW, looking at one of your reply to Reading password and echo * character | Unix Linux Forums | Shell Programming and Scripting. If you don't mind me asking, if is possible for read to read a defined variable or does it always require a user intervention to provide an input?

Below is what I end up using.

#include <stdio.h>

// - UPPER CASE starts at 65
// - LOWER CASE starts at 97

int count;
char uc[26];
char lc[26];

char a, b, c, d, e, f;
char g, h, i, j, k, l;
char m, n, o, p, q, r;
char s, t, u, v, w, x;
char y, z;

//char word[100];
//char *word;

   /* Print the numbers 1 through 20 */

   for ( count = 1; count <= 26; count++ )
          // printf("%d :: %c :: %c \n", count, count+64, count+96);
          uc[count] = (char)count+64;
          lc[count] = (char)count+96;

   // printf("\n ------------------------------------------ \n");

   // d=lc[4];
   // b=lc[2];
   // g=lc[7];
   // u=lc[21];
   // r=lc[18];
   // char word[]={ d, b, t, e, s, t };

   char word[]={ lc[4] , lc[2] , lc[20] , lc[5] , lc[19] , lc[20]  };

   //printf("%c \n",u[26]);
   //printf("%c \n",l[26]);

   return 0;

# 6  
Old 03-10-2014
Wipe it out means something like this:
array[0] = (char)0;
array[1] = (char)0;
array[2] = (char)0;
array[3] = (char)0;
array[4] = (char)0;
array[5] = (char)0;

No matter how it got there, after the string is built you have "hello" sitting in core. Don't let it sit for long.

I don't understand your second question at all. The whole purpose of that script is to read a password that a human types in. That is the only way to have true security. It is always possible to reverse engineer a program that secretly builds a password and discover what that password is.
# 7  
Old 03-10-2014
Originally Posted by ahamed101
How about using shc - Script Compiler?

A few years back I tried to use it and it was awful. It did not support several advanced shell substitutions and arrays - Has it been improved lately?
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