Trustwave's SpiderLabs Security Advisory TWSL2010-002

Trustwave's SpiderLabs Security Advisory TWSL2010-002
Web Service Hijacking in VMWare WebAccess

Published: 2010-03-30 Version: 1.0

Vendor: VMware, Inc (
Product: VMWare VirtualCenter, VMWare ESX
Versions affected: VirtualCenter 2.5, 2.0.x, ESX 3.5, ESX 3.0.x

Product description:
VMWare Infrastructure is a virtualized environment that
allows multiple virtual machines (VMs) to run on a single
physical server. Management can be performed via a
Struts-based web application, or via a thick client. Both
the web interface and the thick client effect all changes
through SOAP calls to an XML web service.

Credit: David Byrne & Tom Leavey of Trustwave's SpiderLabs

CVE: CVE-2009-2277

The Struts-based web application uses the server-side session
attribute "context_vmdirect" to store various settings,
including the URL to the XML web service backend. By default,
the URL is http://localhost/sdk, but the web service URL can be
manually set from a client browser in several locations. One
location is /ui/, by passing a base64-encoded value
to in the "view" parameter as shown below:


Decoded, the view value is:


If wsUrl is changed to point at an external server, all SOAP
calls for that session are sent to the specified server. This
includes plaintext authentication credentials.

An attacker could exploit this by tricking a user into following
a link to /ui/, with an attacker-controlled server
passed in the "view" parameter. Because the "context_vmdirect"
session attribute can be set pre-authentication, and because a
logged-out session can be reused with different credentials, an
attacker could leave a shared browser with a session pointing at
a malicious web service.

Because the authentication credentials used by the management
tools are based on the underlying Linux user accounts, this
attack could lead to a full compromise of the host server.

Vendor Response: The following table lists what action remediates
the vulnerability (column 4) if a solution is available.

VMware Product Running Replace with/
Product Version on Apply Patch
============= ======== ======= =================
vCenter 4.0 Windows not affected
VirtualCenter 2.5 Windows Virtual Center 2.5 Update 6
VirtualCenter 2.0.2 Windows not being fixed at this time *

hosted ** any any not affected

ESXi any ESXi not affected

ESX 4.0 ESX not affected
ESX 3.5 ESX ESX350-201003403-SG
ESX 3.0.3 ESX not being fixed at this time *
ESX 2.5.5 ESX not affected

vMA 4.0 RHEL5 not affected

* Use the workaround of disabling WebAccess to remediate the issue.

** Hosted products are VMware Workstation, Player, ACE, Server, Fusion.

Vendor Communication Timeline:
2009-07-01: Initial contact
2009-07-01: Confirmation of the vulnerabilities
2010-03-29: Fix issued to customers
2010-03-30: Advisory public release


Revision History:
1.0 Initial publication

About Trustwave:
Trustwave is the leading provider of on-demand and
subscription-based information security and payment card
industry compliance management solutions to businesses and
government entities throughout the world. For organizations
faced with today's challenging data security and compliance
environment, Trustwave provides a unique approach with
comprehensive solutions that include its flagship
TrustKeeper compliance management software and other
proprietary security solutions. Trustwave has helped
thousands of organizations--ranging from Fortune 500
businesses and large financial institutions to small and
medium-sized retailers--manage compliance and secure their
network infrastructure, data communications and critical
information assets. Trustwave is headquartered in Chicago
with offices throughout North America, South America,
Europe, Africa, Asia and Australia. For more information,

About Trustwave's SpiderLabs:
SpiderLabs is the advance security team at Trustwave
responsible for incident response and forensics, penetration
testing, application security and security research for
Trustwave's clients. SpiderLabs has responded to hundreds of
security incidents, performed thousands of ethical hacking
exercises and tested the security of hundreds of business
applications for Fortune 500 organizations. For more
information visit

The information provided in this advisory is provided "as
is" without warranty of any kind. Trustwave disclaims all
warranties, either express or implied, including the
warranties of merchantability and fitness for a particular
purpose. In no event shall Trustwave or its suppliers be
liable for any damages whatsoever including direct,
indirect, incidental, consequential, loss of business
profits or special damages, even if Trustwave or its
suppliers have been advised of the possibility of such
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limitation of liability for consequential or incidental
damages so the foregoing limitation may not apply.

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