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Credit:
The information has been provided by Microsoft Security.
The original article can be found at: http://www.microsoft.com/technet/security/Bulletin/MS06-018.mspx
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Vulnerable Systems:
* Microsoft Windows 2000 Service Pack 4 Download the update
* Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service Pack 2 Download the update
* Microsoft Windows Server 2003 Download the update
* Microsoft Windows Server 2003 for Itanium-based Systems Download the update
Immune Systems:
* Microsoft Windows XP Professional x64 Edition
* Microsoft Windows Server 2003 Service Pack 1
* Microsoft Windows Server 2003 x64 Edition
* Microsoft Windows Server 2003 with SP1 for Itanium-based Systems
* Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and Microsoft Windows Millennium Edition (Me)
MSDTC Invalid Memory Access Vulnerability - CVE-2006-0034:
A denial of service vulnerability exists that could allow an attacker to send a specially crafted network message to an affected system. An attacker could cause the Microsoft Distributed Transaction Coordinator (MSDTC) to stop responding. 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.
Mitigating Factors for MSDTC Invalid Memory Access Vulnerability - CVE-2006-0034:
* This is a denial of service vulnerability. This issue would not allow an attacker to execute code or to elevate their user rights, but it could cause the affected service to stop accepting requests.
* If the Microsoft Distributed Transaction Coordinator stops responding because of an attack, services that are not dependant on the Microsoft Distributed Transaction Coordinator would continue to function normally. The affects of an attack will not typically affect the general stability of the system.
* For customers who require the affected component, 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 MSDTC Invalid Memory Access Vulnerability - CVE-2006-0034:
* Disable the Distributed Transaction Coordinator
Disabling the Distributed Transaction Coordinator helps protect the affected system from attempts to exploit this vulnerability. To disable the Distributed Transaction Coordinator, follow these steps:
1. Click Start, and then click Control Panel. Alternatively, click Start, point to Settings, and then click Control Panel.
2. Double-click Administrative Tools.
3. Double-click Component Services.
4. Click Services.
5. Double-click Distributed Transaction Coordinator.
6. In the Startup type list, click Disabled.
7. Click Stop, and then click OK.
You can also stop and disable the Distributed Transaction Coordinator by using the following command at the command prompt:
sc stop MSDTC & sc config MSDTC start= disabled
Impact of Workaround: If you disable the Distributed Transaction Coordinator, you cannot use any service or application that is dependant on the Distributed Transaction Coordinator. This could include other applications such as SQL Server, BizTalk Server, Exchange Server, or Message Queuing. Also, this service is required in most clustering configurations. Therefore, we recommend this workaround only on systems that cannot install the security update.
Use the Group Policy settings to disable the Distributed Transaction Coordinator on all affected systems that do not require this feature.
Because the Distributed Transaction Coordinator is a possible attack vector, disable it by using the Group Policy settings. You can disable the startup of this service at the local, site, domain, or organizational unit level by using Group Policy object functionality in Windows 2000 domain environments or in Windows Server 2003 domain environments. For more information about how to disable this service through logon scripts, see Microsoft Knowledge Base Article 297789
Note You may also review the Windows 2000 Security Hardening Guide. This guide includes information about how to disable services.
For more information about Group Policy, visit the following Web sites:
* Step-by-Step Guide to Understanding the Group Policy Feature Set
* Windows 2000 Group Policy
* Group Policy in Windows Server 2003
Impact of Workaround: If you disable the Distributed Transaction Coordinator, you cannot use any service or application that is dependant on the Distributed Transaction Coordinator. This could include other applications such as SQL Server, BizTalk Server, Exchange Server, or Message Queuing. Also, this service is required in most clustering configurations. Therefore, we recommend this workaround only on systems that cannot install the security update.
* Disable Network DTC Access
If you cannot install the security update, and you cannot disable the Distributed Transaction Coordinator, you may want to disable Network DTC Access. This option is only available on Windows XP and later operating system versions. This still allows local transactions to complete, but it helps protect from network based attacks that try to exploit this issue. For information about how to configure Network DTC Access, visit the following Microsoft Web site. To disable Network DTC Access, follow these steps:
Warning Performing this procedure causes the affected service to start if it was not started previously. Stop the MSDTC service on the MSDTC tab before you close the configuration dialog boxes.
1. Click Start, and then click Control Panel. Alternatively, click Start, point to Settings, and then click Control Panel.
2. Double-click Administrative Tools.
3. Double-Click Component Services, expand Component Services, expand Computers, right-click My Computer and then click Properties,
4. Click the MSDTC tab, and then click Security Configuration.
5. In the Security Configuration dialog box, click to clear the Network DTC Access check box.
Note This sets the following DWORD registry entry to 0 on non-clustering environments. Clustering environments do not read the following registry key. For Clustering environments, follow the steps that are listed in the Disable the Distributed Transaction Coordinator bullet point.
HKLM\Software\Microsoft\MSDTC\Security\NetworkDtcAccess
Note You can also apply this setting to multiple systems by using Group Policy. For more information about Group Policy, visit the following Microsoft Web site.
6. Click OK, close the Component Services dialog box, and then close the Administrative Tools dialog box.
Impact of Workaround: If you disable Network DTC Access, distributed transaction could fail. This could impact other applications such as SQL Server, BizTalk Server, or Message Queuing. Therefore, we recommend this workaround only on systems that cannot install the security update.
Block the following at the firewall:
* All unsolicited inbound traffic on ports greater than 1024
* Any other specifically configured RPC port
These ports can be used to initiate a connection with MSDTC. Blocking them at the firewall will help protect systems that are behind that firewall from attempts to exploit this vulnerability. Also, make sure that you block any other specifically-configured RPC port on the remote system. We recommend that you block all unsolicited inbound communication from the Internet to help prevent attacks that may use other ports. While RPC can use UDP ports 135, 137, 138, 445, and TCP ports 135, 139, 445, and 593, the MSDTC service is not vulnerable over those ports.
Note Other protocols, such as Sequenced Packet Exchange (SPX) or NetBEUI, could be used to communicate with the MSDTC service. If you are using these protocols, you should block the appropriate ports for those protocols. For more information about IPX and SPX, visit the following Microsoft 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.
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. (Windows Sever 2003 displays this as 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. Under Windows Firewall, click Settings.
6. Click On, and then click OK.
7. Click the Exceptions tab. You may need to click Settings to display the exceptions tab.
8. Verify that MSDTC.exe is not in the list of firewall exceptions, 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 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 313190 and Microsoft Knowledge Base Article 813878. RPC uses a broad range of ports, which may make it difficult to try to secure them all by using IPsec. Microsoft Knowledge Base Article 908472 documents how to restrict RPC communication to a set of fixed ports and how to secure those ports by using IPsec.
FAQ for MSDTC Invalid Memory Access Vulnerability - CVE-2006-0034:
What is the scope of the vulnerability?
A denial of service vulnerability exists that could allow an attacker to send a specially crafted network message to an affected system. An attacker could cause the Microsoft Distributed Transaction Coordinator (MSDTC) to stop responding. 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?
An unchecked buffer in the MSDTC service.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could cause the affected service 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 try to exploit the vulnerability by creating a specially crafted network message and sending the message to an affected system. The message could then cause the affected service to stop responding.
What systems are primarily at risk from the vulnerability?
Windows 2000 based versions of the Microsoft Distributed Transaction Coordinator are primarily at risk from this vulnerability because the MSDTC service is enabled by default. Windows XP SP1 and Windows Server 2003 are also at risk if the service is enabled.
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 MDSTC validates the length of a message 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?
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.
MSDTC Denial of Service Vulnerability - CVE-2006-1184:
A denial of service vulnerability exists that could allow an attacker to send a specially crafted network message to an affected system. An attacker could cause the Microsoft Distributed Transaction Coordinator (MSDTC) to stop responding. 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.
Mitigating Factors for MSDTC Invalid Memory Access Vulnerability - CVE-2006-1184:
* This is a denial of service vulnerability. This issue would not allow an attacker to execute code or to elevate their user rights, but it could cause the affected services to stop accepting requests.
* If the Microsoft Distributed Transaction Coordinator stops responding because of an attack, services that are not dependant on the Microsoft Distributed Transaction Coordinator would continue to function normally.
* For customers who require the affected component, 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 MSDTC Denial of Service Vulnerability - CVE-2006-1184:
* Disable the Distributed Transaction Coordinator
Disabling the Distributed Transaction Coordinator helps protect the affected system from attempts to exploit this vulnerability. To disable the Distributed Transaction Coordinator, follow these steps:
1. Click Start, and then click Control Panel. Alternatively, click Start, point to Settings, and then click Control Panel.
2. Double-click Administrative Tools.
3. Double-click Component Services.
4. Click Services.
5. Double-click Distributed Transaction Coordinator.
6. In the Startup type list, click Disabled.
7. Click Stop, and then click OK.
You can also stop and disable the Distributed Transaction Coordinator by using the following command at the command prompt:
sc stop MSDTC & sc config MSDTC start= disabled
Impact of Workaround: If you disable the Distributed Transaction Coordinator, you cannot use any service or application that is dependant on the Distributed Transaction Coordinator. This could include other applications such as SQL Server, BizTalk Server, Exchange Server, or Message Queuing. Also, this service is required in most clustering configurations. Therefore, we recommend this workaround only on systems that cannot install the security update.
* Use the Group Policy settings to disable the Distributed Transaction Coordinator on all affected systems that do not require this feature.
Because the Distributed Transaction Coordinator is a possible attack vector, disable it by using the Group Policy settings. You can disable the startup of this service at the local, site, domain, or organizational unit level by using Group Policy object functionality in Windows 2000 domain environments or in Windows Server 2003 domain environments. For more information about how to disable this service through logon scripts, see Microsoft Knowledge Base Article 297789
Note You may also review the Windows 2000 Security Hardening Guide. This guide includes information about how to disable services.
For more information about Group Policy, visit the following Web sites:
* Step-by-Step Guide to Understanding the Group Policy Feature Set
* Windows 2000 Group Policy
* Group Policy in Windows Server 2003
Impact of Workaround: If you disable the Distributed Transaction Coordinator, you cannot use any service or application that is dependant on the Distributed Transaction Coordinator. This could include other applications such as SQL Server, BizTalk Server, Exchange Server, or Message Queuing. Also, this service is required in most clustering configurations. Therefore, we recommend this workaround only on systems that cannot install the security update.
Disable Network DTC Access
If you cannot install the security update, and you cannot disable the Distributed Transaction Coordinator, you may want to disable Network DTC Access. This option is only available on Windows XP and later operating system versions. This still allows local transactions to complete, but it helps protect from network based attacks that try to exploit this issue. For information about how to configure Network DTC Access, visit the following Microsoft Web site. To disable Network DTC Access, follow these steps:
Warning Performing this procedure causes the affected service to start if it was not started previously. Stop the MSDTC service on the MSDTC tab before you close the configuration dialog boxes.
1. Click Start, and then click Control Panel. Alternatively, click Start, point to Settings, and then click Control Panel.
2. Double-click Administrative Tools.
3. Double-Click Component Services, expand Component Services, expand Computers, right-click My Computer and then click Properties,
4. Click the MSDTC tab, and then click Security Configuration.
5. In the Security Configuration dialog box, click to clear the Network DTC Access check box.
Note This sets the following DWORD registry entry to 0 on non-clustering environments. Clustering environments do not read the following registry key. For Clustering environments, follow the steps that are listed in the Disable the Distributed Transaction Coordinator bullet point.
HKLM\Software\Microsoft\MSDTC\Security\NetworkDtcAccess
Note You can also apply this setting to multiple systems by using Group Policy. For more information about Group Policy, visit the following Microsoft Web site.
6. Click OK, close the Component Services dialog box, and then close the Administrative Tools dialog box.
Impact of Workaround: If you disable Network DTC Access, distributed transaction could fail. This could impact other applications such as SQL Server, BizTalk Server, or Message Queuing. Therefore, we recommend this workaround only on systems that cannot install the security update.
* Block the following at the firewall:
* All unsolicited inbound traffic on ports greater than 1024
* Any other specifically configured RPC port
These ports can be used to initiate a connection with MSDTC. Blocking them at the firewall will help protect systems that are behind that firewall from attempts to exploit this vulnerability. Also, make sure that you block any other specifically-configured RPC port on the remote system. We recommend that you block all unsolicited inbound communication from the Internet to help prevent attacks that may use other ports. While RPC can use UDP ports 135, 137, 138, 445, and TCP ports 135, 139, 445, and 593, the MSDTC service is not vulnerable over those ports.
Note Other protocols, such as Sequenced Packet Exchange (SPX) or NetBEUI, could be used to communicate with the MSDTC service. If you are using these protocols, you should block the appropriate ports for those protocols. For more information about IPX and SPX, visit the following Microsoft 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.
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. (Windows Sever 2003 displays this as 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. Under Windows Firewall, click Settings.
6. Click On, and then click OK.
7. Click the Exceptions tab. You may need to click Settings to display the exceptions tab.
8. Verify that MSDTC.exe is not in the list of firewall exceptions, 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 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 313190 and Microsoft Knowledge Base Article 813878. RPC uses a broad range of ports, which may make it difficult to try to secure them all by using IPsec. Microsoft Knowledge Base Article 908472 documents how to restrict RPC communication to a set of fixed ports and how to secure those ports by using IPsec.
FAQ for MSDTC Denial of Service Vulnerability - CVE-2006-1184:
What is the scope of the vulnerability?
A denial of service vulnerability exists that could allow an attacker to send a specially crafted network message to an affected system. An attacker could cause the Distributed Transaction Coordinator to stop responding. 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?
An unchecked buffer in the MSDTC service.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could cause the affected service 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 try to exploit the vulnerability by creating a specially crafted network message and sending the message to an affected system. The message could then cause the affected service to stop responding.
What systems are primarily at risk from the vulnerability?
Windows 2000 based versions of the Microsoft Distributed Transaction Coordinator are primarily at risk from this vulnerability because the MSDTC service is enabled by default. Windows XP SP1 and Windows Server 2003 are also at risk if the service is enabled.
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 MDSTC validates the length of a message 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?
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.
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