[NT] Microsoft Window Utility Manager Local Elevation of Privileges (MS04-019)
From: SecuriTeam (support_at_securiteam.com)
To: firstname.lastname@example.org Date: 14 Jul 2004 10:21:13 +0200
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Microsoft Window Utility Manager Local Elevation of Privileges (MS04-019)
A local elevation of privileges exists in the Windows Utility Manager
which allows any user to take complete control over the operating system.
This vulnerability affects the Windows 2000 operating system family.
The Microsoft Windows 2000 operating system family supports a feature
called Accessibility Options. Accessibility Options are a series of
technologies that assist users within Windows. The aim of these
technologies is to help users with disabilities access the functions of
the operating system. They can be enabled or disabled using shortcuts
built into the operating system or through the Accessibility Utility
Manager. The Accessibility Utility Manager allows users to start, stop, or
monitor accessibility programs such as Microsoft Magnifier, Narrator,
On-Screen Keyboard, etc... The Utility Manager can be invoked by pressing
<Windows key>+U or, if the user is an Administrator, by executing
"utilman.exe /start" from the command line. The Utility Manager runs as a
Windows service enabled by default. When executed it runs within the
interactive desktop with Local System privileges.
Utility Manager supports context sensitive help which was accessed by
clicking the "?" on the title bar of the Utility Manager window and then
clicking an object or by pressing F1 key after selecting an object. To
display the context sensitive help, Utility Manager loaded winhlp32.exe.
However it did not drop System privileges when doing so meaning that
winhlp32.exe was executed under the Local System account. Microsoft fixed
this vulnerability with patch MS04-011. The patch failed to fix the
problem because it only removed the context sensitive help from the
Utility Manager GUI preventing help from being invoked from the main
screen. However, the patch did not remove/disable the functionality used
by the application to launch the context sensitive help (see for more
details). Utility Manager continues to load winhlp32.exe without dropping
privileges meaning that winhlp32.exe is still run under Local System
account. A user need only to send several Windows messages and
winhlp32.exe will be launched. From there, the user can open any file as a
Local System account.
To exploit the vulnerability, an attacker would need only to run the
//get window handle
lHandle=FindWindow(NULL, "Utility Manager");
//send right click on the app button in the taskbar or Alt+Space Bar
//send WM_COMMANDHELP 0x0365 lParam must be<>NULL
After this code has been executed, winhlp32.exe will ask the attacker to
locate the umandlg.hlp help file. The attacker can then select "Yes" and
an Open dialog will be shown. The attacker can then search and select
cmd.exe. The attacker will then have a shell running under Local System
It seems that Visual C++ MFC (Microsoft Foundation Class) (see) will
automatically include help functionality in an application regardless of
whether or not this functionality will be utilized. Therefore, when coding
desktop applications that will run with elevated privileges, remove all
help functionality or drop account privileges before loading the help.
Disable Utility Manager Service.
The information has been provided by <mailto:email@example.com> Vivek
Rathod (Application Security, Inc.).
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