bugtraq - Beginners error: Windows Live Mail 2011 runs rogue C:\Program.exe when opening associated URLs

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Date: Sat, 16 Aug 2014 15:30:57 +0200
From: "Stefan Kanthak" <stefan.kanthak@...go.de>
To: <bugtraq@...urityfocus.com>
Cc: <fulldisclosure@...lists.org>
Subject: Beginners error: Windows Live Mail 2011 runs rogue C:\Program.exe when opening associated URLs

Hi @ll,

the following command lines associated with the URL protocols of
Windows Live Mail 2011 (15.4.3538.513)

WLMail.Url.Mailto=C:\Program Files (x86)\Windows Live\Mail\wlmail.exe /mailurl:"%1"
WLMail.Url.news=C:\Program Files (x86)\Windows Live\Mail\wlmail.exe /newsurl:"%1"
WLMail.Url.nntp=C:\Program Files (x86)\Windows Live\Mail\wlmail.exe /newsurl:"%1"
WLMail.Url.snews=C:\Program Files (x86)\Windows Live\Mail\wlmail.exe /newsurl:"%1"

execute the rogue programs "C:\Program.exe", "C:\Program Files\Windows.exe"
(on x86) resp. "C:\Program Files.exe" or "C:\Program Files (x86)\Windows.exe"
(on x64) with the credentials of the user whenever the user opens one of the
associated URLs.

>From <http://msdn.microsoft.com/library/cc144175.aspx>
or <http://msdn.microsoft.com/library/cc144101.aspx>:

| Note: If any element of the command string contains or might contain
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| spaces, it must be enclosed in quotation marks. Otherwise, if the
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| element contains a space, it will not parse correctly. For instance,
| "My Program.exe" starts the application properly. If you use
| My Program.exe without quotation marks, then the system attempts to
| launch My with Program.exe as its first command line argument.

Since every user account created during Windows setup has administrative
rights every user owning such an account can create the rogue program(s),
resulting in a privilege escalation.

JFTR: no, the "user account control" is not a security boundary!

      From <http://support.microsoft.com/kb/2526083>:

| Same-desktop Elevation in UAC is not a security boundary and can be hijacked
| by unprivileged software that runs on the same desktop. Same-desktop
| Elevation should be considered a convenience feature, and from a security
| perspective, "Protected Administrator" should be considered the equivalent
| of "Administrator."

JFTR: if you or your customers, family etc. still use Windows Live Mail 2011,
      see <https://technet.microsoft.com/library/security/ms13-045> and upgrade
      to Windows Live Mail 2012 ASAP!

regards
Stefan Kanthak

PS: the associations for .eml and .nws DONT show this beginners error:

    WindowsLiveMail.Email.1="C:\Program Files (x86)\Windows Live\Mail\wlmail.exe" /eml:%1
    WindowsLiveMail.News.1="C:\Program Files (x86)\Windows Live\Mail\wlmail.exe" /nws:%1

    Unfortunately their argument %1 is not quoted, see above!