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Vulnerabilities in TCP/IP IPv6 Allows DoS (MS06-064)
------------------------------------------------------------------------
SUMMARY
Multiple vulnerabilities in TCP/IP IPv6 have been discovered, allowing a
remote attacker to cause Windows to no longer respond. A denial of service
vulnerability exists in the IPv6 Windows implementation of the Internet
Control Message Protocol (ICMP). An attacker who successfully exploited
this vulnerability could cause the affected system to drop an existing TCP
connection. A denial of service vulnerability exists in the IPv6 Windows
implementation of TCP. An attacker who successfully exploited this
vulnerability could cause the affected system to drop an existing TCP
connection. A denial of service vulnerability exists in Windows in the
IPv6 implementation of TCP/IP. An attacker who successfully exploited this
vulnerability could cause the affected system to stop responding.
DETAILS
Affected Software:
* Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service
Pack 2 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=9fd73d12-ff7c-411d-944d-a6f147b20775>
Download the update
* Microsoft Windows XP Professional x64 Edition -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=fc98f55c-520e-4a68-a3c3-0df51c6122bb>
Download the update
* Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service
Pack 1 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=102591a0-2b58-497b-bc20-593571b96e9c>
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=12515d47-134d-4d1f-9ae7-f0a7167ec424>
Download the update
* Microsoft Windows Server 2003 x64 Edition -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=c5faba34-48f5-4875-a0fa-6b8207f9b276>
Download the update
Non-Affected Software:
* Microsoft Windows 2000 Service Pack 4
ICMP Connection Reset Vulnerability - CVE-2004-0790:
A denial of service vulnerability exists in the IPv6 Windows
implementation of the Internet Control Message Protocol (ICMP). An
attacker who successfully exploited this vulnerability could cause the
affected system to drop an existing TCP connection.
Mitigating Factors for ICMP Connection Reset Vulnerability -
CVE-2004-0790:
* Firewall best practices and firewall or router configurations that
block all ICMP traffic 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.
* IPv6 support is not installed by default on Windows XP Service Pack 1,
Windows XP Service Pack 2, Windows Server 2003 and Windows Server 2003
Service Pack 1.
* An attacker s system must belong to the same IPv6 network as the target
system.
* An attacker must first predict or discover the IP address and port
information of the source and of the destination of an existing TCP
network connection.
* This attack would have to be performed on each TCP connection that was
targeted for reset. Many applications will automatically restore
connections that have been reset.
Workarounds for ICMP Connection Reset Vulnerability - CVE-2004-0790:
Microsoft has tested the following workarounds. While 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.
* Uninstall IPv6.
For the IPv6 protocol for Windows XP with SP2, Windows XP with SP1, or
Windows Server 2003, do the following:
1. Log on to the computer with a user account that has privileges to
change network configuration.
2. Click Start, click Control Panel, and then double-click Network
Connections.
3. Click Microsoft TCP/IP version 6 (for Windows XP with SP2 or Windows
Server 2003) or Microsoft IPv6 Developer Edition (for Windows XP with
SP1), and then click Uninstall.
4. When prompted to confirm the removal of the Microsoft IPv6 Developer
Edition or Microsoft TCP/IP version 6 protocol, click OK.
Alternately, from the Windows XP or Windows Server 2003 desktop do the
following:
1. Click Start, point to Programs, point to Accessories.
2. Click Command Prompt.
3. At the command prompt, type netsh interface ipv6 uninstall.
Impact of Workaround: Uninstalling IPv6 would result in the system not
being able to communicate with other hosts on an IPv6 configured network.
* Block all ICMP network packets at the firewall or at the router:
ICMP network packets are used to initiate a connection with the affected
components. Blocking them at the firewall or at the router will help
protect systems that are behind that firewall or router from attempts to
exploit this vulnerability. We recommend that you block all unsolicited
inbound communication from the Internet.
Impact of Workaround: This workaround can also negatively impact
performance by preventing TCP from optimizing network communication. ICMP
network packets can eliminate fragmentation at routers connecting networks
with different MTUs. Fragmentation reduces TCP throughput and increases
network congestion.
Note: Windows XP Service Pack 1 Firewall is unable to handle IPv6 network
traffic. In order to ensure protection for your Windows XP Service Pack 1
system using the Internet Connection Firewall you should apply the update
identified in KB Article 817778 Overview of the Advanced Networking Pack
for Windows XP .
* Block ICMP traffic 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 313190 and
Microsoft Knowledge Base Article 813878.
Impact of Workaround: This workaround can also negatively impact
performance by preventing TCP from optimizing network communication. ICMP
network packets can eliminate fragmentation at routers connecting networks
with different MTUs. Fragmentation reduces TCP throughput and increases
network congestion.
FAQ for ICMP Connection Reset Vulnerability - CVE-2004-0790:
What is the scope of the vulnerability?
A denial of service vulnerability exists in Windows in the IPv6
implementation of the Internet Control Message Protocol (ICMP). An
attacker who successfully exploited this vulnerability could cause the
affected system to drop an existing TCP connection.
What causes the vulnerability?
Specially crafted ICMP packets are being parsed when they should be
dropped which may cause the reset of an existing connection.
What is IPv6?
Internet Protocol version 6 (IPv6), a new suite of standard protocols for
the network layer of the Internet, is built into Microsoft Windows XP and
later. IPv6 is designed to solve many of the problems of the current
version of IP (known as IPv4) such as address depletion, security,
autoconfiguration, and extensibility. To learn more about IPv6, please
read the following Microsoft FAQ for IPv6.
What is TCP/IP?
TCP/IP is a set of networking protocols. TCP/IP includes standards for how
computers communicate and conventions for connecting networks and for
routing traffic. For more information about TCP/IP, see the following
Microsoft Web site.
What is ICMP?
Internet Control Message Protocol (ICMP) is a required TCP/IP standard.
"Internet Control Message Protocol (ICMP)." Hosts and routers that use IP
communication can report errors and exchange limited control and status
information using ICMP.
ICMP messages are usually sent automatically in one of the following
situations:
* An IP datagram cannot reach its destination.
* An IP router (gateway) cannot forward datagrams at the current rate of
transmission.
* An IP router redirects the sending host to a better route to the
destination.
You can use the ping command to send ICMP echo request messages and to
record the receipt of ICMP echo reply messages. By using these messages,
you can detect network or host communication failures and troubleshoot
common TCP/IP connectivity problems. For more information about ICMP, see
the following Microsoft Web site.
What might an attacker use the vulnerability to do?
An attacker who exploited this vulnerability could cause the affected
system to reset TCP connections.
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. An attacker s
system must belong to the same IPv6 network as a target system.
How could an attacker exploit the vulnerability?
An attacker could 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 reset TCP network connections.
What systems are primarily at risk from the vulnerability?
All affected operating systems are at risk from this vulnerability.
However, servers are at primary risk from this vulnerability because they
maintain connections with clients that could be vulnerable to the
connection reset.
Could the vulnerability be exploited over the Internet?
Yes. An attacker could try to exploit this vulnerability over the
Internet. By default, the Microsoft Internet Connection Firewall (ICF) in
Windows XP Service Pack 1 and in Windows Server 2003 allows these kinds of
network packets and cannot be used to filter them by default. The firewall
component in Windows XP Service Pack 2 and Windows Server 2003 Service
Pack 1 called Windows Firewall is able to block this traffic. If you are
running IPv6 on a Windows XP Service Pack 1 you should apply update
identified in KB Article 817778 Overview of the Advanced Networking Pack
for Windows XP to get an updated Internet Connection Firewall which is
able to handle IPv6 traffic.
What does the update do?
The update removes the vulnerability by modifying the way that the
affected operating systems validate ICMP requests.
When this security bulletin was issued, had this vulnerability been
publicly disclosed?
Yes. This vulnerability has been publicly disclosed as affecting the IPv4
implementation of TCP/IP. It has been assigned Common Vulnerability and
Exposure number CVE-2004-0790. There is a variant of this issue that has
been assigned Common Vulnerability and Exposure number CVE-2004-0791. The
Microsoft security update for CVE-2004-0790 also addresses CVE-2004-0791.
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.
How does this vulnerability relate to the vulnerability that is corrected
by MS05-019?
MS05-19 addressed the same vulnerability in the more commonly adopted and
deployed IPv4 implementation of TCP/IP. This update addresses the
vulnerability in the IPv6 implementation.
TCP Connection Reset Vulnerability - CVE-2004-0230:
A denial of service vulnerability exists in the IPv6 Windows
implementation of TCP. An attacker who successfully exploited this
vulnerability could cause the affected system to drop an existing TCP
connection.
Mitigating Factors for TCP Connection Reset Vulnerability - CVE-2004-0230:
* An attacker must be able to predict or discover the IP address and port
information of the source and of the destination of an existing TCP
network connection. An attacker would also have to predict or to learn
certain difficult TCP network packet details. Protocols or programs that
maintain long sessions and have predictable TCP/IP information are at an
increased risk for this issue.
* IPv6 support is not installed by default on Windows XP Service Pack 1
and Windows XP Service Pack 2, Windows Server 2003 and Windows Server 2003
Service Pack 1.
* An attacker's system must belong to the same IPv6 network as the target
system.
* 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. Affected
systems that allow any TCP connections to the Internet may be vulnerable
to this issue.
* This attack would have to be performed on each TCP connection that was
targeted for reset. Many applications will automatically restore
connections that have been reset.
Workarounds for TCP Connection Reset Vulnerability - CVE-2004-0230:
Microsoft has tested the following workarounds. While 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.
* Uninstall IPv6.
For the IPv6 protocol for Windows XP with SP2, Windows XP with SP1, or
Windows Server 2003, do the following:
1. Log on to the computer with a user account that has privileges to
change network configuration.
2. Click Start, click Control Panel, and then double-click Network
Connections.
3. Click Microsoft TCP/IP version 6 (for Windows XP with SP2 or Windows
Server 2003) or Microsoft IPv6 Developer Edition (for Windows XP with
SP1), and then click Uninstall.
4. When prompted to confirm the removal of the Microsoft IPv6 Developer
Edition or Microsoft TCP/IP version 6 protocol, click OK.
Alternately, from the Windows XP or Windows Server 2003 desktop do the
following:
1. Click Start, point to Programs, point to Accessories.
2. Click Command Prompt.
3. At the command prompt, type netsh interface ipv6 uninstall.
Impact of Workaround: Uninstalling IPv6 would result in the system not
being able to communicate with other hosts on an IPv6 configured network.
FAQ for TCP Connection Reset Vulnerability - CVE-2004-0230:
What is the scope of the vulnerability?
A denial of service vulnerability exists in the IPv6 Windows
implementation of TCP. An attacker who successfully exploited this
vulnerability could cause the affected system to drop an existing TCP
connection.
What causes the vulnerability?
Specially crafted TCP packets are being parsed when they should be dropped
which may cause the reset of an existing connection.
What is IPv6?
Internet Protocol version 6 (IPv6), a new suite of standard protocols for
the network layer of the Internet, is built into Microsoft Windows XP and
later. IPv6 is designed to solve many of the problems of the current
version of IP (known as IPv4) such as address depletion, security,
autoconfiguration, and extensibility. To learn more about IPv6, please
read the following Microsoft FAQ for IPv6.
What is TCP/IP?
TCP/IP is a set of networking protocols. TCP/IP includes standards for how
computers communicate and conventions for connecting networks and for
routing traffic. For more information about TCP/IP, see the following
Microsoft Web site.
What might an attacker use the vulnerability to do?
An attacker who exploited this vulnerability could cause the affected
system to reset TCP connections.
Who could exploit the vulnerability?
Any anonymous user who could deliver a specially crafted message to the
affected system and learn or predict the required TCP details could try to
exploit this vulnerability. An attacker s system must belong to the same
IPv6 network as a target system.
How could an attacker exploit the vulnerability?
An attacker could 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 reset TCP connections.
An attacker must be able to predict or discover the IP address and port
information of the source and of the destination of an existing TCP
network connection. An attacker would also have to predict or learn
certain difficult TCP network packet details.
What systems are primarily at risk from the vulnerability?
All affected operating systems are at risk from this vulnerability.
However, servers are at primary risk from this vulnerability because they
maintain connections with clients that could be vulnerable to the
connection reset. Protocols or programs that maintain long sessions and
have predictable TCP/IP information are at an increased risk to this
issue.
Could the vulnerability be exploited over the Internet?
Yes. An attacker could try to exploit this vulnerability over the
Internet.
What does the update do?
The update removes the vulnerability by modifying the way that the
affected operating systems validate TCP requests.
When this security bulletin was issued, had this vulnerability been
publicly disclosed?
Yes. This vulnerability has been publicly disclosed. It has been assigned
Common Vulnerability and Exposure number CVE-2004-0230.
When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had seen examples of proof of concept code published
publicly but had not received any information to indicate that this
vulnerability had been publicly used to attack customers when this
security bulletin was originally issued.
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 proof of concept code that has
been publicly published. The vulnerability that has been addressed has
been assigned the Common Vulnerability and Exposure number CVE-2004-0230.
How does this vulnerability relate to the vulnerability that is corrected
by MS05-019?
MS05-19 addressed the same vulnerability in the more commonly adopted and
deployed IPv4 implementation of TCP/IP. This update addresses the
vulnerability in the IPv6 implementation.
Spoofed Connection Request Vulnerability - CVE-2005-0688:
A denial of service vulnerability exists in Windows in the IPv6
implementation of TCP/IP. An attacker who successfully exploited this
vulnerability could cause the affected system to stop responding.
Mitigating Factors for Spoofed Connection Request Vulnerability -
CVE-2005-0688:
* IPv6 support is not installed by default on Windows XP Service Pack 1,
Windows XP Service Pack 2 and Windows Server 2003 and Windows Server 2003
Service Pack 1.
* An attacker s system must belong to the same IPv6 network as the target
system.
* The affected system return to a normal operational state after the
specially crafted packets are finished processing.
* A typical network deployment scenario would limit the attack to an
individual network segment as most routers will not forward these kinds of
specially crafted TCP/IP network packets.
* 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. Affected
systems that allow any IP connections to the Internet may be vulnerable to
this issue.
Workarounds for Spoofed Connection Request Vulnerability - CVE-2005-0688:
Microsoft has tested the following workarounds. While 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.
* Uninstall IPv6.
For the IPv6 protocol for Windows XP with SP2, Windows XP with SP1, or
Windows Server 2003, do the following:
1. Log on to the computer with a user account that has privileges to
change network configuration.
2. Click Start, click Control Panel, and then double-click Network
Connections.
3. Click Microsoft TCP/IP version 6 (for Windows XP with SP2 or Windows
Server 2003) or Microsoft IPv6 Developer Edition (for Windows XP with
SP1), and then click Uninstall.
4. When prompted to confirm the removal of the Microsoft IPv6 Developer
Edition or Microsoft TCP/IP version 6 protocol, click OK.
Alternately, from the Windows XP or Windows Server 2003 desktop do the
following:
1. Click Start, point to Programs, point to Accessories.
2. Click Command Prompt.
3. At the command prompt, type netsh interface ipv6 uninstall.
Impact of Workaround: Uninstalling IPv6 would result in the system not
being able to communicate with other hosts on an IPv6 configured network.
FAQ for Spoofed Connection Request Vulnerability - CVE-2005-0688:
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 for a
limited time as a result of excessive CPU utilization. During that time,
affected systems cannot respond to requests. Note that the denial of
service vulnerability would not allow an attacker to execute code or
elevate their user rights, but it could cause the affected system to stop
accepting requests.
What causes the vulnerability?
The affected operating systems perform incomplete validation of TCP/IP
network packets. This vulnerability occurs when a Transmission Control
Protocol (TCP) SYN packet is received with a spoofed source Internet
Protocol (IP) address and port number that is identical to that of the
destination IP address and port. The effect of this makes it appear that
the host computer has sent a packet to itself. If this attack is
successful, a loop is created and extra computer CPU time is used.
What is IPv6?
Internet Protocol version 6 (IPv6), a new suite of standard protocols for
the network layer of the Internet, is built into Microsoft Windows XP and
later. IPv6 is designed to solve many of the problems of the current
version of IP (known as IPv4) such as address depletion, security,
autoconfiguration, and extensibility. To learn more about IPv6, please
read the following FAQ for IPv6.
What is TCP/IP?
TCP/IP is a set of networking protocols. TCP/IP includes standards for how
computers communicate and conventions for connecting networks and for
routing traffic. For more information about TCP/IP, see the following. For
more information about TCP/IP, see the following Microsoft Web site.
What might an attacker use the vulnerability to do?
An attacker who exploited this vulnerability could cause the affected
system to stop responding.
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 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 stop responding.
What systems are primarily at risk from the vulnerability?
All affected operating systems are at risk from this vulnerability.
Could the vulnerability be exploited over the Internet?
Yes. An attacker could try to exploit this vulnerability over the
Internet. However, this attack requires that routers forward malformed
TCP/IP network packets. Most routers will not forward these kinds of
malformed TCP/IP network packets.
What does the update do?
The update removes the vulnerability by modifying the way that the
affected operating systems validate TCP/IP requests.
When this security bulletin was issued, had this vulnerability been
publicly disclosed?
Yes. This vulnerability has been publicly disclosed for the IPv4
implementation of TCP/IP. It has been assigned Common Vulnerability and
Exposure number CVE-2005-0688. It also has been named Land Attack by the
larger security community.
When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had seen examples of proof of concept code published
publicly but had not received any information to indicate that this
vulnerability had been publicly used to attack customers using IPv6 when
this security bulletin was originally issued.
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 demonstrated
by the existing proof of concept code that has been published.
How does this vulnerability relate to the vulnerability that is corrected
by MS05-019?
MS05-19 addressed the same vulnerability in the more commonly adopted and
deployed IPv4 implementation of TCP/IP. This update addresses the
vulnerability in the IPv6 implementation.
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/MS06-064.mspx>
http://www.microsoft.com/technet/security/Bulletin/MS06-064.mspx
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