Source Code 1992 March/Source_Code_CD-ROM_Walnut_Creek_March_1992.iso/usenet/altsrcs/3/3920/ypcrack

Text File | 1991-08-28 | 5.1 KB | 170 lines

#!/usr/local/bin/perl
# ypcrack: AJCD 27/8/91
#
# Crack passwords in YP password file incrementally; warns users and system
# manager about cracked passwords.
#
# Usage: ypcrack [-debug] [-crack] [-verbose] [-mail sysmgr]

$prog = $0; $prog =~ s%.*/%%;
$dir = $0; $dir =~ s%/[^/]*$%%;

chdir ($dir) || die "$0: can't chdir to $dir\n";

$debug = 0;            # testing?
$crack = 0;            # if testing, do we still crack properly?
$verbose = 0;            # talk about it?
$mail = "faults";        # who to mail report to

while ($_ = shift(@ARGV)) {
   if (/^-d(ebug)?$/)       { $debug = 1; }
   elsif (/^-c(rack)?$/)    { $crack = 1; }
   elsif (/^-v(erbose)?$/)  { $verbose = 1; }
   elsif (/^-m(ail)?$/)     { $mail = shift(@ARGV); }
   else {
      print STDERR "Usage: $prog [-debug] [-verbose] [-mail sysmgr] [-crack]\n";
      exit 1;
   }
}

sub onfield {
   local(@one) = split(/:/, $a);
   local(@two) = split(/:/, $b);
   return ($one[0] cmp $two[0]);
}

sub mail {
   local($to) = shift(@_);
   local($subject) = shift(@_);
   local($temp) = "/tmp/$prog.$$";
   open(TEMP, ">$temp") || die "$prog: can't open temp file $temp\n";
   print TEMP @_, "\n";
   close(TEMP);
   if ($debug) {
      print STDERR "To: $to\n", "Subject: $subject\n";
      system ("cat <$temp");
   } else {
      system ("mail -s $subject $to < $temp");
   }
   unlink($temp) || die "$prog: can't remove temp file $temp\n";
}

if (! $debug) {
   print STDERR "Getting new password file\n" if ($verbose);
   rename("passwd", "passwd.old"); # ignore failure
   system("ypcat passwd >passwd")/256 && die "$prog: ypcat failed: $!\n";
}

print STDERR "Sorting passwd\n" if ($verbose);
open(PASSWD, "passwd") || die "$prog: can't open passwd\n";
@passwd = <PASSWD>;
close(PASSWD);
@passwd = sort onfield @passwd;

if (open(PASSWD, "passwd.old")) {
   print STDERR "Sorting passwd.old\n" if ($verbose);
   @oldpasswd = <PASSWD>;
   close(PASSWD);
   @oldpasswd = sort onfield @oldpasswd;
} else {
   @oldpasswd = ();
}

print STDERR "Reading previously cracked accounts\n" if ($verbose);
if (open(CRACKED, "cracked.last")) {
   @lasttime = <CRACKED>;
   close(CRACKED);
} else {
   @lasttime = ();
}

@diffs = ();
$newp = 1;            # new passwd entry required
print STDERR "Differencing passwd and passwd.old\n" if ($verbose);
foreach $entry (@passwd) {
   ($name,$pwd) = split(/:/, $entry);
   $done = 0;
   while (! $done) {
      ($oname,$opwd) = split(/:/, shift(@oldpasswd)) if ($newp);
      if ($name eq $oname) {
     push(@diffs, $entry) if ($pwd ne $opwd ||
                  grep($name eq substr($_, $[, index($_, " ")),
                       @lasttime));
     $newp = 1;
     $done = 1;
      } elsif ($name lt $oname) {
     push(@diffs, $entry);
     $newp = 0;
     $done = 1;
      } else { # $name gt $oname
     $newp = 1;
      }
   }
}

if ($debug) {
   print STDERR "Passwords changed:\n";
   print STDERR @diffs;
}

if ($#diffs >= 0) {
   open(CRACKED, ">pwdiff") || die "$prog: can't create pwdiff\n";
   print CRACKED @diffs;
   close(CRACKED);
   print STDERR "Starting Crack on pwdiff\n" if ($verbose);
   if ($debug && ! $crack) {
      @cracked = grep(s/.*Guessed (\w*).*\[(.*)\].*/\1 \2/, `cat debug.out`);
   } else {
      @cracked = grep(s/.*Guessed (\w*).*\[(.*)\].*/\1 \2/, `Crack -f pwdiff`);
   }
   if ($debug) {
      print STDERR "Cracked accounts:\n";
      print STDERR @cracked;
   }
   # check for previously cracked accounts, mail crackee
   foreach $twit (@cracked) {
      ($name, $pwd) = split(" ", $twit);
      if (grep($name eq substr($_, $[, index($_, " ")), @lasttime)) {
     chop $twit; $twit .= " ***\n";
     print STDERR "Disabling $name [$pwd]: cracked already\n" if ($verbose);
     &mail($name, "Your password",
"Your password ($pwd) has been guessed by the password cracker twice\
in a row.\

PLEASE CHANGE IT TO SOMETHING MORE SECURE *NOW*.

The system manager will soon check that you have changed your password, and\
disable your account if you have not.\
\
Secure passwords are generally six characters or longer, and include a mixture\
of upper and lower-case alphabetic characters, punctuation, and digits.");
      } else {
     print STDERR "Mailing $name about password $pwd\n" if ($verbose);
     &mail($name, "Your password",
"Your password ($pwd) has been guessed by the password cracker.\

PLEASE CHANGE IT TO SOMETHING MORE SECURE.\
\
If you do not, your account will be disabled next time the password cracker\
is run.\
\
Secure passwords are generally six characters or longer, and include a mixture\
of upper and lower-case alphabetic characters, punctuation, and digits.");
      }
   }
   if ($#cracked >= 0) {
      print STDERR "Mailing report to $mail\n" if ($verbose);
      &mail($mail, "Cracked passwords", "User Password\n\n", @cracked, "
Entries marked *** have been cracked before. The account should be disabled
if the user does not change the password now.");
   }
   open(CRACKED, ">cracked.last") || die "$prog: can't update cracked.last\n";
   print CRACKED @cracked;
   close(CRACKED);
   chmod 0600, "cracked.last" || die "$prog: can't protect cracked.last\n";
} else {
   print STDERR "No changed passwords\n" if ($verbose);
   open(CRACKED, ">cracked.last") || die "$prog: can't clean cracked.last\n";
   close(CRACKED);
}