[UNIX] mysqlhotcopy Insecure Temporary File (copy_index)

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  mysqlhotcopy Insecure Temporary File (copy_index)
------------------------------------------------------------------------


SUMMARY

mysqlhotcopy is "a fast on-line hot-backup utility for local MySQL 
databases and tables".

A vulnerability in mysqlhotcopy allows local attackers to cause the 
product to overwrite create a symbolic link in the /tmp/ directory that 
will be then overwritten by the mysqlhotcopy utility.

DETAILS

Insecure temporary file vulnerability in the mysqlhotcopy script has been 
discovered. This insecure temporary file occurs when using the scp (Secure 
CoPy) method that is part of the mysql-server package. Creating a 
temporary file whose name is predictable enough to allow overwriting of 
arbitrary files causes the vulnerability.

Vulnerable code:
Under the function copy_index, the following code can be seen:
  my $tmpfile="$opt_tmpdir/mysqlhotcopy$$";

This file is then written to by the script.

Patch:
The following is Debian's mysqlhotcopy provided patch:
--- mysql-3.23.49.orig/scripts/mysqlhotcopy.sh
+++ mysql-3.23.49/scripts/mysqlhotcopy.sh
@@ -7,6 +7,8 @@
 use File::Path;
 use DBI;
 use Sys::Hostname;
+use File::Copy;
+use File::Temp;

 =head1 NAME

@@ -585,7 +587,6 @@
 sub copy_index
 {
   my ($method, $files, $source, $target) = @_;
- my $tmpfile="$opt_tmpdir/mysqlhotcopy$$";

   print "Copying indices for ".@$files." files...\n" unless $opt{quiet};
   foreach my $file (@$files)
@@ -613,21 +614,21 @@
     }
     elsif ($opt{method} eq 'scp')
     {
- my $tmp=$tmpfile;
- open(OUTPUT,">$tmp") || die "Can\'t create file $tmp: $!\n";
- if (syswrite(OUTPUT,$buff) != length($buff))
+ my ($fh, $tmp)=tempfile('mysqlhotcopy-XXXXXX', DIR => $opt_tmpdir);
+ die "Can\'t create/open file in $opt_tmpdir\n";
+ if (syswrite($fh,$buff) != length($buff))
       {
  die "Error when writing data to $tmp: $!\n";
       }
- close OUTPUT || die "Error on close of $tmp: $!\n";
- safe_system("scp $tmp $to");
+ close $fh || die "Error on close of $tmp: $!\n";
+ safe_system("$opt{method} $tmp $to");
+ unlink $tmp;
     }
     else
     { die "Can't use unsupported method '$opt{method}'\n";
     }
   }
- unlink "$tmpfile" if ($opt{method} eq 'scp');
 }


ADDITIONAL INFORMATION

The information has been provided by  <mailto:jeroen@wolffelaar.nl> Jeroen 
van Wolffelaar.



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