Effects 

MS09-025 is not categorized as virus, worm, Trojan or backdoor. It is a group of important vulnerabilities in the Windows Kernel on Windows Server 2008/Vista/2003/XP/2000 computers, which allows to gain local privilege escalation.

The kernel is the core of the operating system and provides basic services for all other parts of the operating system.

The addressed vulnerabilities are:

• Windows Kernel Desktop Vulnerability: it occurs because the Windows kernel does not properly validate changes in certain kernel objects.
• Windows Kernel Pointer Vulnerability: it occurs because the Windows kernel does not properly validate certain pointers passed from user mode.
• Windows Driver Class Registration Vulnerability: it occurs because the Windows kernel does not properly validate an argument passed to a system call.
• Windows Desktop Parameter Edit Vulnerability: it occurs because the Windows kernel does not properly validate input passed from user mode to the kernel when editing a specific desktop parameter.

If exploited successfully, MS09-025 allows to gain unauthorized privileges on a computer or network. An example of privilege elevation would be an unprivileged user who could manage to be added to the Administrator's group. In such case, the hacker could take complete control of the system: create, modify or delete files, install programs, create new user accounts, etc.

MS09-025 is usually exploited by running a specially crafted program in the vulnerable computer. In order to do so, a hacker must be able to log on locally to the system.

If you have a Windows Server 2008/Vista/2003/XP/2000 computer, it is recommended to download and apply the security patch for this vulnerability. Click here to access the web page for downloading the patch.

Bear in mind that this security patch replaces a previous one, called MS09-006.