TUCoPS :: VMWare :: b06-3834.htm

VMware Possible Incorrect Permissions On SSL Key Files
Advisory: VMware Possible Incorrect Permissions On SSL Key Files
Advisory: VMware Possible Incorrect Permissions On SSL Key Files

======================================================================== VMware Possible Incorrect Permissions On SSL Key Files
= VMWare Advisory:
= http://kb.vmware.com/kb/2467205 
= Affected Software:
=    VMware Player for Linux
=    VMware Workstation for Linux
=    VMware Server for Linux
=    VMware ESX Server 2.x
=    VMware Infrastructure 3
= Public disclosure on July 18, 2006
== Overview =
The configuration program, vmware-config.pl, does not correctly chmod
the highly-sensitive generated key file which is used for encrypting
traffic for remote administrative connections.

In vmware-config.pl on VMWare Server v1.0 beta (Linux build 24927),
lines 6376 - 6382 are meant to chmod the key and certificate files to
safe values. However, it does not use the custom safe_chmod()
sub-routine which reports errors on failure. Instead, the native Perl
chmod() function is used, without any return code checking.

  # Make key readable only by root (important)
  chmod 0400, shell_string("$certLoc") . '/' .
shell_string("$certPrefix")  . '.key';

  # Let anyone read the certificate
  chmod 0444, shell_string("$certLoc") . '/' .
shell_string("$certPrefix")  . '.crt';

The targets used with the aforementioned chmod() functions are joined
together with some parts generated from using a subroutine called
shell_string(). This is intended to generate shell representations of a
string, which is not desired for generating a file path. This causes the
target passed to chmod() to be incorrect.

Because the safe_chmod() subroutine is not used and no return code
checks are performed, the user is not alerted of the chmod() failing.

Depending on the umask being used at the time, this could leave the key
file readable to any local user on the system.

== Exploitation =
Exploitation requires local file access on the VMWare product host and
appropriate network access. File access could potentially be obtained by
manipulating additional existing services. In example, an attacker may
be able to leverage required file access via insecure scripts hosted by
an HTTP daemon.

Various types of SSL-related attacks can be performed once the key has
been obtained.

== Solutions =
Manually change the permissions on the key and certificate to its
intended values. The following commands would be appropriate on a
default installation:

# chmod 400 /etc/vmware/ssl/rui.key
# chmod 444 /etc/vmware/ssl/rui.crt

== Credit =
Discovered and advised to VMWare June, 2006 by Nick Breese of

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