mod_auth-any/4034: htpasswd uses small salt

[Rich Wales <ri...@leland.stanford.edu>]

>Number:         4034
>Category:       mod_auth-any
>Synopsis:       htpasswd uses small salt
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    apache
>State:          open
>Class:          sw-bug
>Submitter-Id:   apache
>Arrival-Date:   Wed Mar 10 17:20:01 PST 1999
>Last-Modified:
>Originator:     richw@leland.stanford.edu
>Organization:
apache
>Release:        1.3.4
>Environment:
FreeBSD wyattearp.stanford.edu 3.1-RELEASE FreeBSD 3.1-RELEASE #1: Sat Mar  6 11:20:34 PST 1999     richw@wyattearp.stanford.edu:/misc/3.1/usr/src/sys/compile/WYATTEARP  i386
>Description:
Encrypted passwords created by "htpasswd" use 12-bit (two-byte) salts, even on
systems (such as FreeBSD) that use improved password hashing algorithms and can
support longer salts.
>How-To-Repeat:
On a FreeBSD 2.x / 3.x system, configured to use MD5-based password hashing,
create a password file with "htpasswd -c" and note that the salt (between the
second and third dollar signs) is only two bytes long.  Compare with the pass-
word strings in /etc/master.passwd, which use longer salts.
>Fix:
The "add_password" routine in htpasswd.c can be enhanced to generate a longer
salt string.  Here is a patch that worked for me.  Alternatively, the author-
ization code could be rewritten to use a different password scheme altogether.

*** src/support/htpasswd.c.orig Mon Jul 13 04:32:58 1998
--- src/support/htpasswd.c      Mon Sep 21 16:21:26 1998
***************
*** 12,17 ****
--- 12,18 ----
  
  #include "ap_config.h"
  #include <sys/types.h>
+ #include <sys/time.h>
  #include <signal.h>
  
  #ifndef CHARSET_EBCDIC
***************
*** 114,120 ****
  
  static void add_password(char *user, FILE *f)
  {
!     char *pw, *cpw, salt[3];
  
      pw = strd((char *) getpass("New password:"));
      if (strcmp(pw, (char *) getpass("Re-type new password:"))) {
--- 115,122 ----
  
  static void add_password(char *user, FILE *f)
  {
!     char *pw, *cpw, salt[7];
!     struct timeval tv;
  
      pw = strd((char *) getpass("New password:"));
      if (strcmp(pw, (char *) getpass("Re-type new password:"))) {
***************
*** 123,131 ****
            unlink(tn);
        exit(1);
      }
!     (void) srand((int) time((time_t *) NULL));
!     to64(&salt[0], rand(), 2);
!     salt[2] = '\0';
      cpw = (char *)crypt(pw, salt);
      free(pw);
      fprintf(f, "%s:%s\n", user, cpw);
--- 125,138 ----
            unlink(tn);
        exit(1);
      }
! 
!     /* generate longer salt (in case enhanced password code can use it) */
!     gettimeofday(&tv, 0);
!     srand((unsigned) tv.tv_sec);
!     to64(&salt[0], rand(), 3);
!     to64(&salt[3], tv.tv_usec, 3);
!     salt[6] = '\0';
! 
      cpw = (char *)crypt(pw, salt);
      free(pw);
      fprintf(f, "%s:%s\n", user, cpw);
***************
*** 220,225 ****
--- 227,236 ----
          {
                  fputs(command,f);
          } 
+ 
+       /* get rid of any excess leftover text in password file */
+       fflush(f);
+       ftruncate(fileno(f), ftell(f));
  
      fclose(f);
      fclose(tfp);

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