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Credit:
The information has been provided by Microsoft Product Security.
The original article can be found at: http://www.microsoft.com/technet/security/Bulletin/MS06-063.mspx
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Affected Software:
* 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 XP Professional x64 Edition - Download the update
* Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1 - Download the update
* Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft Windows Server 2003 with SP1 for Itanium-based Systems - Download the update
* Microsoft Windows Server 2003 x64 Edition - Download the update
Server Service Denial of Service Vulnerability- CVE-2006-3942:
A denial of service vulnerability exists in the Server service because of the way it handles certain network messages. An attacker could exploit the vulnerability by sending a specially crafted network message to a computer running the Server service. An attacker who successfully exploited this vulnerability could cause the computer to stop responding.
Mitigating Factors for Server Service Denial of Service Vulnerability - CVE-2006-3942:
* 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 Server Service Denial of Service Vulnerability - CVE-2006-3942:
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 the following at the firewall:
* UDP ports 135, 137, 138, and 445, and TCP ports 135, 139, 445, and 593
* 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 features 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, 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
FAQ for Server Service Denial of Service Vulnerability - CVE-2006-3942:
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. During that time, the server would be unable to respond to requests. 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 uninitialized buffer in the Server service.
What is the Server service?
The Server service provides remote procedure cal (RPC) support, file and 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.
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 stop responding.
What systems are primarily at risk from the vulnerability?
All Windows computers are equally 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. 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 initializing a buffer before it is used.
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-2006-3942. It also has been named Mailslot DOS 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 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 potentially could be exploited by using the published proof of concept code. The vulnerability that has been addressed has been assigned the Common Vulnerability and Exposure number CVE-2006-3942.
How does this vulnerability relate to the vulnerabilities that are corrected by MS06-035 and MS06-040?
All three vulnerabilities were in the Server service. However, this update addresses a new vulnerability that was not addressed as part of MS06-035 or as part of MS06-040. MS06-035 and MS06-040 help protect against the vulnerabilities that were discussed in those bulletins, but do not address this new vulnerability. This update does not replace MS06-040. You must install this update and the update that is provided as part of the MS06-040 security bulletin to help protect your system against both vulnerabilities. This bulletin does replace MS06-035. Installing this update will protect against all vulnerabilities fixed in MS06-035.
SMB Rename Vulnerability - CVE-2006-4696:
A remote code execution vulnerability exists in the Server service because of the way it handles certain network messages. An attacker could exploit the vulnerability sending a specially crafted network message to a computer running the Server service as an authenticated user. An attacker who successfully exploited this vulnerability could take complete control of the affected system.
Mitigating Factors for SMB Rename Vulnerability - CVE-2006-4696:
* 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.
* An attacker must have valid logon credentials and be able to log on over the network to exploit this vulnerability. The vulnerability could not be exploited by anonymous users.
Workarounds for SMB Rename Vulnerability - CVE-2006-4696:
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 the following at the firewall:
* UDP ports 135, 137, 138, and 445, and TCP ports 135, 139, 445, and 593
* 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 features 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, 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.
FAQ for SMB Rename Vulnerability - CVE-2006-4696:
What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who exploited this vulnerability could take complete control of an affected system.
What causes the vulnerability?
The vulnerability is caused by the Server service attempting to dereference an invalid pointer.
What is the Server service?
The Server service provides RPC support, file and 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.
Who could exploit the vulnerability?
Any authenticated 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.
What systems are primarily at risk from the vulnerability?
All Windows computers are equally 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. 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 removing the faulty code.
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.
How does this vulnerability relate to the vulnerabilities that are corrected by MS06-035 and MS06-040?
All three vulnerabilities were in the Server service. However, this update addresses a new vulnerability that was not addressed as part of MS06-035 or as part of MS06-040. MS06-035 and MS06-040 help protect against the vulnerabilities that were discussed in those bulletins, but do not address this new vulnerability. This update does not replace MS06-040. You must install this update and the update that is provided as part of the MS06-040 security bulletin to help protect your system against both vulnerabilities. This bulletin does replace MS06-035. Installation of this update will protect against the vulnerabilities addressed in MS06-035.
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