User Interface Privilege Isolation (UIPI) is a technology introduced in
Windows Vista
Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...
and
Windows Server 2008
Windows Server 2008 is the fourth release of the Windows Server operating system produced by Microsoft as part of the Windows NT family of the operating systems. It was released to manufacturing on February 4, 2008, and generally to retail on F ...
to combat
shatter attack In computing, a shatter attack is a programming technique employed by hackers on Microsoft Windows operating systems to bypass security restrictions between processes in a session. A shatter attack takes advantage of a design flaw in Windows's me ...
exploits. By making use of
Mandatory Integrity Control Mandatory Integrity Control (MIC) is a core security feature of Windows Vista and later that adds mandatory access control to running processes based on their Integrity Level (IL). The IL represents the level of trustworthiness of an object. This ...
, it prevents processes with a lower "integrity level" (IL) from sending messages to higher IL processes (except for a very specific set of UI messages).
Window messages are designed to communicate user action to processes. However, they can be used to
run arbitrary code in the receiving process' context. This could be used by a malicious low-privilege processes to run arbitrary code in the context of a higher-privilege process, which constitutes an unauthorized
privilege escalation
Privilege escalation is the act of exploiting a bug, a design flaw, or a configuration oversight in an operating system or software application to gain elevated access to resources that are normally protected from an application or user. The re ...
. By restricting the ability of lower-privileged processes to send window messages to higher-privileged processes, UIPI can mitigate these kinds of attacks.
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UIPI, and Mandatory Integrity Control more generally, is a security feature but not a security ''boundary''.