Re: High Risk Vulnerability in Lexmark Printer Sharing Service

Here is a lexmark related local Security issue… I never got anywhere
with regard to disclosure… enjoy

Lexmark skins code execution.

Either LEXBCES.exe, LXBKPSWX.exe, LXBKJSWX.exe, or LEXPPS.exe allows
interaction from the user while running as SYSTEM. This interaction can
lead to CMD.exe running as NT AUTHORITY\SYSTEM. I can not figure out
which is the cause yet.

This information was tested on Lexmark X1185 all in one printer . Other
printers and Dell versions of the Lexmark printer line may also be
affected. Due to the lack of access to the specified devices I can not
verify this information further.

Print any document. Wait for the voice to come through your speakers and
say "Printing started". Click the "Appearance" icon on the window that
has popped up near your systray. Once the next window pops up click
"Additional styles (skins) are available on the Lexmark web site."

You should now have a browser running as SYSTEM.

Navigate to c:\windows\system32\ right click on cmd.exe and click execute.

This can obviously be automated via shatter style messaging ala
SendMessage() and PostMessage().

-KF

NGSSoftware Insight Security Research wrote:

> Peter Winter-Smith of NGSSoftware has discovered a high risk
> vulnerability
> in the Lexmark Printer Sharing service which could allow a remote,
> unauthenticated attacker to execute arbitrary code on a Lexmark printer
> user's computer system with Local System privileges.
>
> There is no known official patch or workaround for this issue, as Lexmark
> have proven unresponsive throughout the investigation and have failed
> to provide us with a response to our queries on many occasions.
>
> Communications between NGS and Lexmark to date are summed up in the
> following time-line:
>
> [28/09/2005] Initial email to [email protected]
> [28/09/2005] Automated reply from [email protected]
> [29/09/2005] Re-sent email to [email protected] … No response
> [03/10/2005] Mass mail to [email protected], [email protected],
> [email protected], [email protected] … No response
> [04/10/2005] First response from Lexmark's 'Task ID IE THIRD LEVEL
> ESCALATIONS' thanking NGS for the email dated the 28th Sept.
> asking for further details.
> [04/10/2005] Details of the vulnerability provided to Lexmark … No
> response
> [11/10/2005] Follow-up email to Lexmark … No response
> [18/10/2005] Follow-up email to Lexmark … No response
> [24/10/2005] Follow-up email to Lexmark … No response
> [08/11/2005] Follow-up email to Lexmark … No response
> [30/12/2005] Follow-up email to Lexmark … No response
> [07/01/2006] Informing Lexmark of this advisory … No response
>
>> From our tests it seems that the following workaround will prevent the
>
> vulnerability from being present by removing the vulnerable service so
> that
> it cannot start. This should not prevent the printer from working in
> normal
> operations, however if a user is depending on the Lexmark Printer Sharing
> services for network printing this workaround may impact that level of
> functionality.
>
> NGS do not take any responsibility for the following information being
> correct or for any of the results which may occur as a result of
> taking the
> following actions.
>
> Workaround:
>
> 1. Launch the Services console by taking the following actions:
> - Click the 'Start' menu.
> - Select 'Run'.
> - In the 'Run' command text area type 'services.msc' and click 'Ok'.
> 2. Find and right click the 'LexBce Server' entry. From the right
> click menu
> select the 'Stop' item. Confirm that you wish to stop the service
> and all
> dependencies.
> 3. Open the '%systemroot%\system32' folder by taking the following
> actions:
> - Click the 'Start' menu.
> - Select 'Run'.
> - In the 'Run' command text area type '%systemroot%\system32' and click
> 'Ok'.
> 4. Locate the file named 'LexPPS.EXE'. Right click this file and select
> 'Rename'. Enter a new name for the file, I recommend 'LexPPS.EXE.vuln'.
> 5. In the Services console, locate and right click the 'LexBce Server'
> and
> select 'Start'.
> 6. In the Services console, locate and right click the 'Print Spooler'
> and
> select 'Start'.
>
> This disclosure was made in accordance with the NGS responsible
> disclosure
> policy which can be viewed online at:
>
> http://www.ngssoftware.com/disclosure.pdf
>
> NGSSoftware will withhold technical details of this flaw for at least one
> month. Full technical details will be published on or after the 7th March
> 2006.
>
> NGSSoftware Insight Security Research
> http://www.ngssoftware.com
> http://www.databasesecurity.com/
> http://www.nextgenss.com/
> +44(0)208 401 0070
>
>
>
>