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Vulnerability in Windows TCP/IP Allows DoS (MS08-004)
------------------------------------------------------------------------
SUMMARY
This important update resolves a privately reported vulnerability in
Transmission Control Protocol/Internet Protocol (TCP/IP) processing. An
attacker who successfully exploited this vulnerability could cause the
affected system to stop responding and automatically restart.
This is an important security update for all supported editions of Windows
Vista. For more information, see the subsection, Affected and Non-Affected
Software, in this section.
This security update addresses the vulnerability by validating the IP
address provided by a DHCP server or assigned by command or API at the
local machine.
DETAILS
Affected Software
Operating System - Maximum Security Impact - Aggregate Severity Rating -
Bulletins Replaced by this Update
*
<http://www.microsoft.com/downloads/details.aspx?familyid=8ce9608b-7049-47cd-adc4-22a803877d33>
Windows Vista - Denial of Service - Important - MS08-001
*
<http://www.microsoft.com/downloads/details.aspx?familyid=d7b9c3d1-9c23-4e05-bac6-d0b327feaf53>
Windows Vista x64 Edition - Denial of Service - Important - MS08-001
Non-Affected Software
* Microsoft Windows 2000 Service Pack 4
* Windows XP Service Pack 2
* Windows XP Professional x64 Edition and Windows XP Professional x64
Edition Service Pack 2
* Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack
2
* Windows Server 2003 x64 Edition and Windows 2003 Server x64 Edition
Service Pack 2
* Windows Server 2003 with SP1 for Itanium-based Systems and Windows
Server 2003 with SP2 for Itanium based Systems
* Windows Vista Service Pack 1 (all editions)
* Windows Server 2008 (all editions)
Windows Vista TCP/IP Vulnerability - CVE-2008-0084
A denial of service vulnerability exists in TCP/IP processing in Windows
Vista. An attacker could exploit the vulnerability by creating a specially
crafted DHCP server that returns a specially crafted packet to a host,
corrupting TCP/IP structures and causing the affected system to stop
responding and automatically restart.
CVE Information:
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0084>
CVE-2008-0084
Mitigating Factors for Windows Vista TCP/IP Vulnerability - CVE-2008-0084
Mitigation refers to a setting, common configuration, or general
best-practice, existing in a default state, that could reduce the severity
of exploitation of vulnerability. The following mitigating factors may be
helpful in your situation:
* An attacker can only receive a DHCP request and respond with a
specially crafted packet by using a specially crafted DHCP server within
the same link or via a DHCP Relay Agent.
Workarounds for Windows Vista TCP/IP Vulnerability - CVE-2008-0084
Workaround refers to a setting or configuration change that does not
correct the underlying vulnerability but would help block known attack
vectors before you apply the update. Microsoft has tested the following
workarounds and states in the discussion whether a workaround reduces
functionality:
* Assign a static IP address to the client computer instead of allowing
the client computer to automatically request an IP address. Perform the
following steps:
1. On the client computer, click Control Panel, then click Network and
Sharing Center.
2. Local Area Connection and click View Status.
3. Click Properties.
4. Click Internet Protocol Version 4 (TCP/IPv4) and click Properties.
5. Select Use the following IP address and enter the values in IP address,
Subnet mask, Default gateway, and Preferred DNS server.
6. Click OK.
Impact of workaround Automatic requests for an IP address have been
bypassed.
How to undo the workaround. Re-enable automatic requests for an IP address
by performing the following steps:
1. On the client computer, click Control Panel, then click Network and
Sharing Center or Network Connections.
2. Local Area Connection and click View Status.
3. Click Properties.
4. Click Internet Protocol Version 4 (TCP/IPv4) click Properties.
5. Select Obtain an IP address automatically.
6. Click OK.
FAQ for Windows Vista TCP/IP Vulnerability - CVE-2008-0084
What is the scope of the vulnerability?
This is a denial of service vulnerability. An attacker who exploited this
vulnerability could cause the affected system to stop responding and
automatically restart. Note that the denial of service vulnerability would
not allow an attacker to execute code or to elevate their user rights, but
it could cause the affected system to stop accepting requests.
What causes the vulnerability?
The vulnerability lies in the way that the TCP/IP stack handles packets
received from DHCP servers.
What is DHCP?
Dynamic Host Configuration Protocol (DHCP) is a protocol used by networked
devices (hosts) to obtain various parameters necessary for the hosts to
operate in an Internet Protocol (IP) network. By using this protocol,
system administration workload greatly decreases, and devices can be added
to the network with minimal or no manual configurations. A DHCP server
assigns IP addresses to host computers.
What is TCP/IP? Is TCP/IP vulnerable?
TCP/IP is the suite of communications protocols used for transmitting data
over networks. The current version of TCP/IP is TCP/IPv4, which is
vulnerable (see also the Workarounds section of this vulnerability entry).
The next version, TCP/IPv6, is not affected by this vulnerability.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could cause an
affected system to become non-responsive and automatically restart.
How could an attacker exploit the vulnerability?
An attacker could exploit the vulnerability by creating a specially
crafted DHCP server that returns a specially crafted packet to a host,
corrupting TCP/IP structures and causing the affected system to stop
responding and automatically restart.
What systems are primarily at risk from the vulnerability?
Windows Vista clients that request an IP address from the DHCP server are
primarily at risk.
What does the update do?
The update removes the vulnerability by adding more validation to the way
that the TCP/IP stack handles packets received from DHCP servers.
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?
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.
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/ms08-004.mspx>
http://www.microsoft.com/technet/security/bulletin/ms08-004.mspx
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