[NT] Vulnerability in Windows Kernel Allows Elevation of Privilege (MS05-055)

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Vulnerability in Windows Kernel Allows Elevation of Privilege (MS05-055)
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SUMMARY

A privilege elevation vulnerability exists in the way that asynchronous
procedure calls are processed within the kernel.

An attacker who successfully exploited this vulnerability could take
complete control of an affected system. An attacker could then install
programs; view, change, or delete data; or create new accounts with full
user rights.

DETAILS

Vulnerable Systems:
* Microsoft Windows 2000 Service Pack 4 (
<http://www.microsoft.com/downloads/details.aspx?FamilyId=3832FF23-6B04-4CA2-80B9-D344B4CC98EA> Download the update)

Immune Systems:
* Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service
Pack 2
* Microsoft Windows XP Professional x64 Edition
* Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service
Pack 1
* Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft
Windows Server 2003 with SP1 for Itanium-based Systems
* Microsoft Windows Server 2003 x64 Edition
* Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and
Microsoft Windows Millennium Edition (ME)

Windows Kernel Vulnerability:
A privilege elevation vulnerability exists in the way that asynchronous
procedure calls are processed within the kernel. This vulnerability could
allow a logged on user to take complete control of the system.

Mitigating Factors:
An attacker must have valid logon credentials and be able to log on
locally to exploit this vulnerability. The vulnerability could not be
exploited remotely or by anonymous users.

Workarounds:
Microsoft have not identified any workarounds for this vulnerability.

FAQ:
What is the scope of the vulnerability?
This is a <http://go.microsoft.com/fwlink/?LinkId=21142> privilege
elevation vulnerability. An attacker who successfully exploited this
vulnerability could take complete control of an affected system. An
attacker could then install programs; view, change, or delete data; or
create new accounts with full user rights. To attempt to exploit the
vulnerability, an attacker must be able to log on locally to the system
and run a program.

What causes the vulnerability?
The method used to process items in the asynchronous procedure call (APC)
queue list.

What is an asynchronous procedure call (APC)?
An asynchronous procedure call (APC) is a function that executes
asynchronously in the context of a particular thread. For more
information, please visit the following
<http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/asynchronous_procedure_calls.asp> Microsoft web site.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could take
complete control of the affected system.

Who could exploit the vulnerability?
To try to exploit the vulnerability, an attacker must be able to log on
locally to a system and run a program. To exploit this vulnerability, an
attacker would first have to log on to the system. An attacker could then
run a specially-crafted application that could exploit the vulnerability
and gain complete control over the affected system.

What systems are primarily at risk from the vulnerability?
Workstations and terminal servers are primarily at risk. Servers could be
at more risk if users who do not have sufficient administrative
permissions are given the ability to log on to servers and to run
programs. However, best practices strongly discourage allowing this.

Could the vulnerability be exploited over the Internet?
No. An attacker must be able to log on to the specific system that is
targeted for attack. An attacker cannot load and run a program remotely by
using this vulnerability.

What does the update do?
The update addresses the vulnerability by modifying the way that
Asynchronous Procedure Calls (APC) queues are processed.

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure. Microsoft had not received any information to
indicate that this vulnerability had been publicly disclosed when this
security bulletin was originally issued.

When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this
vulnerability had been publicly used to attack customers and had not seen
any examples of proof of concept code published when this security
bulletin was originally issued.

CVE Information:
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-2827>
CAN-2005-2827


ADDITIONAL INFORMATION

The original article can be found at:
<http://www.microsoft.com/technet/security/bulletin/MS05-055.mspx>
http://www.microsoft.com/technet/security/bulletin/MS05-055.mspx



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