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Vulnerability in Server Service Allows Remote Code Execution (MS06-040)
------------------------------------------------------------------------
SUMMARY
There is a remote code execution vulnerability in Server Service that
could allow an attacker who successfully exploited this vulnerability to
take complete control of the affected system.
DETAILS
Affected Software:
* Microsoft Windows 2000 Service Pack 4 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=3b61153d-359f-4441-a448-24062cb2387c>
Download the update
* Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service
Pack 2 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=2996b9b6-03ff-4636-861a-46b3eac7a305>
Download the update
* Microsoft Windows XP Professional x64 Edition -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=314c7c2c-9a02-4e56-98cf-97703fecf0be>
Download the update
* Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service
Pack 1 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=a0058f39-6dea-4dfc-9dd6-4cb45b305dec>
Download the update
* Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft
Windows Server 2003 with SP1 for Itanium-based Systems -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=af970833-2044-4284-937d-3beb2e2f286d>
Download the update
* Microsoft Windows Server 2003 x64 Edition -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=3b0c1954-fca5-4e95-abb2-6066a9d6bc76>
Download the update
Mitigating Factors for Buffer Overrun in Server Service Vulnerability -
CVE-2006-3439:
* Firewall best practices and standard default firewall configurations
can help protect networks from attacks that originate outside the
enterprise perimeter. Best practices recommend that systems that are
connected to the Internet have a minimal number of ports exposed.
Workarounds for Buffer Overrun in Server Service Vulnerability -
CVE-2006-3439:
Microsoft has tested the following workarounds. Although these workarounds
will not correct the underlying vulnerability, they help block known
attack vectors. When a workaround reduces functionality, it is identified
in the following section.
* Block TCP ports 139 and 445 at the firewall:
This port is used to initiate a connection with the affected component.
Blocking TCP ports 139 and 445 at the firewall will help protect systems
that are behind that firewall from attempts to exploit this vulnerability.
We recommend that you block all unsolicited inbound communication from the
Internet to help prevent attacks that may use other ports. For more
information about ports, visit the following Web site.
* To help protect from network-based attempts to exploit this
vulnerability, use a personal firewall, such as the Internet Connection
Firewall, which is included with Windows XP and with Windows Server 2003.
By default, the Internet Connection Firewall feature in Windows XP and in
Windows Server 2003 helps protect your Internet connection by blocking
unsolicited incoming traffic. We recommend that you block all unsolicited
incoming communication from the Internet. In Windows XP Service Pack 2
this feature is called the Windows Firewall.
To enable the Internet Connection Firewall feature by using the Network
Setup Wizard, follow these steps:
1. Click Start, and then click Control Panel.
2. In the default Category View, click Network and Internet Connections,
and then click Setup or change your home or small office network. The
Internet Connection Firewall feature is enabled when you select a
configuration in the Network Setup Wizard that indicates that your system
is connected directly to the Internet.
To configure Internet Connection Firewall manually for a connection,
follow these steps:
1. Click Start, and then click Control Panel.
2. In the default Category View, click Networking and Internet
Connections, and then click Network Connections.
3. Right-click the connection on which you want to enable Internet
Connection Firewall, and then click Properties.
4. Click the Advanced tab.
5. Click to select the Protect my computer or network by limiting or
preventing access to this computer from the Internet check box, and then
click OK.
Note If you want to enable certain programs and services to communicate
through the firewall, click Settings on the Advanced tab, and then select
the programs, the protocols, and the services that are required.
* To help protect from network-based attempts to exploit this
vulnerability, enable advanced TCP/IP filtering on systems that support
this feature.
You can enable advanced TCP/IP filtering to block all unsolicited inbound
traffic. For more information about how to configure TCP/IP filtering, see
Microsoft Knowledge Base Article <http://support.microsoft.com/kb/309798>
309798.
* To help protect from network-based attempts to exploit this
vulnerability, block the affected ports by using IPSec on the affected
systems.
Use Internet Protocol security (IPSec) to help protect network
communications. Detailed information about IPSec and about how to apply
filters is available in Microsoft Knowledge Base Article
<http://support.microsoft.com/kb/313190> 313190 and Microsoft Knowledge
Base Article <http://support.microsoft.com/kb/813878> 813878.
What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who
successfully exploited this vulnerability could remotely 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.
What causes the vulnerability?
An unchecked buffer in the Server service.
What is the Server service?
The Server service provides RPC support, file print support and named pipe
sharing over the network. The Server service allows the sharing of your
local resources (such as disks and printers) so that other users on the
network can access them. It also allows named pipe communication between
applications running on other computers and your computer, which is used
for RPC.
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?
Any anonymous user who could deliver a specially crafted message to the
affected system could try to exploit this vulnerability.
How could an attacker exploit the vulnerability?
An attacker could try to exploit the vulnerability by creating a specially
crafted message and sending the message to an affected system. The message
could then cause the affected system to execute code.
What systems are primarily at risk from the vulnerability?
While all workstations and servers are at risk regarding this issue,
Windows 2000 systems are primarily at risk due to the unique
characteristics of the vulnerability and affected code path.
Could the vulnerability be exploited over the Internet?
Yes. An attacker could try to exploit this vulnerability over the
Internet. Firewall best practices and standard default firewall
configurations can help protect against attacks that originate from the
Internet. Microsoft has provided information about how you can help
protect your PC. End users can visit the Protect Your PC Web site. IT
professionals can visit the Security Guidance Center Web site.
What does the update do?
The update removes the vulnerability by modifying the way that Server
service validates the length of a message it receives in RPC
communications before it passes the message to the allocated buffer.
When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure.
When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
Yes. When the security bulletin was released, Microsoft had received
information that this vulnerability was being exploited.
Does applying this security update help protect customers from the code
that has been published publicly that attempts to exploit this
vulnerability?
Yes. This security update addresses the vulnerability that is currently
being exploited. The vulnerability that has been addressed has been
assigned the Common Vulnerability and Exposure number CVE-2006-3439.
How does this vulnerability relate to the vulnerability that is corrected
by MS06-035?
While both vulnerabilities were in Server service this update addresses a
new vulnerability that was not addressed as part of MS06-035. MS06-035
helps protect against the vulnerability that is discussed in that
bulletin, but does not address this new vulnerability. This update does
not replace MS06-035. You must install this update and the update that is
provided as part of the MS06-035 security bulletin to help protect your
system against both vulnerabilities.
ADDITIONAL INFORMATION
The information has been provided by Microsoft Product Security.
The original article can be found at:
<http://www.microsoft.com/technet/security/Bulletin/MS06-040.mspx>
http://www.microsoft.com/technet/security/Bulletin/MS06-040.mspx
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