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                                    CERT-Renater

                         Note d'Information No. 2006/VULN397
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DATE                      : 12/07/2006

HARDWARE PLATFORM(S)      : /

OPERATING SYSTEM(S)       : Windows 2000, XP, 2003

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MS06-036 Buffer Overrun in DHCP Client Service Vulnerability
CVE-2006-2372

Affected Software:
    - Microsoft Windows 2000 Service Pack 4
    - Microsoft Windows XP Service Pack 1
    - Microsoft Windows XP Service Pack 2
    - Microsoft Windows XP Professional x64 Edition
    - Microsoft Windows Server 2003
    - Microsoft Windows Server 2003 Service Pack 1
    - Microsoft Windows Server 2003 for Itanium-based Systems
    - Microsoft Windows Server 2003 with SP1 for Itanium-based Systems
    - Microsoft Windows Server 2003 x64 Edition

Non-Affected Software:
    - Microsoft Windows 98
    - Microsoft Windows 98 Second Edition (SE)
    - Microsoft Windows Millennium Edition (Me)

There is a remote code execution vulnerability in the DHCP Client service
that could allow an attacker who successfully exploited this vulnerability
to take complete control of the affected system.

Mitigating Factors
- ------------------	
For an attack to be successful the attacker must send the affected host a
specially crafted DHCP response communication from the same network subnet.

Workarounds
- -----------
Microsoft has tested the following workarounds. Although these workarounds
will not correct the underlying vulnerability, they help block known attack
vectors.	

Use a static IP address
   To configure the system to use a static IP address follow these steps:

   1. Obtain a static IP address from your network administrator

   2. Click Start, and then click Control Panel and then click Network and
      Internet Connections.

   3. Right-click the connection on which you want to specify to use a static
      IP address, and then click Properties.

   4. Select Internet Protocol (TCP/IP) and click Properties.

   5. On the General tab, click on the Use the following IP address and Use
      the following DNS server addresses radio buttons.

   6. Input your static IP address, subnet mask, default gateway, and DNS
      servers.

   7. Click Ok twice.

   8. Repeat steps 3 through 7 for each of your network adapters.
	
Disable the DHCP Client service
   Disabling the DHCP Client service will help protect the affected system
   from attempts to exploit this vulnerability. To disable the DHCP Client
   service, follow these steps:

   1. Click Start, and then click Control Panel. Alternatively, point to
      Settings, and then click Control Panel.

   2. Double-click Administrative Tools.

   3. Double-click Services.

   4. Double-click DHCP Client.

   5. In the Startup type list, click Disabled.

   6. Click Stop, and then click OK.

You can also stop and disable the DHCP service by using the following
command at the command prompt:

   sc stop DHCP & sc config DHCP start= disabled

Impact of Workaround: If you disable the DHCP service, you cannot
                       automatically retrieve an IP address from a DHCP
                       Server. Without an IP address you will not be able to
                       connect to the network.

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