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

https://www.trustwave.com/spiderlabs/advisories/TWSL2010-002.txt

Published: 2010-03-30 Version: 1.0

Vendor: VMware, Inc (http://www.vmware.com)
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

Finding:
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/vmDirect.do, by passing a base64-encoded value 
to in the "view" parameter as shown below:

/ui/vmDirect.do?view=d3NVcmw9aHR0cDovL2xvY2FsaG9zdC9zZGsmdm1JZD1WaXJ0dWFsTWFjaGluZXwxMjgmdWk9OQ==_

Decoded, the view value is: 

wsUrl=http://localhost/sdk&vmId=VirtualMachine|128&ui=9

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/vmDirect.do, 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

References
1. http://lists.vmware.com/pipermail/security-announce/2010/000086.html

Revision History: 
1.0 Initial publication

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