Exploit code has been observed publicly to demonstrate the Microsoft Windows Server Service Remote Procedure Call request handling code execution vulnerability.
Microsoft Windows contains a buffer overflow vulnerability that could allow an unauthenticated, remote attacker to create a denial of service (DoS) condition or execute arbitrary code.
The vulnerability is due to insufficient boundary checking in the Server service. An attacker could exploit the vulnerability by sending an remote procedure call (RPC) request designed to trigger an error condition. As a result of this error, an attacker could create a DoS condition or execute arbitrary code with the elevated privileges of the Server service.
Exploit code is publicly available.
Microsoft has confirmed the vulnerability and released software updates.
The following versions of Windows are vulnerable:
Windows 2000 SP4 and prior
Windows XP SP3 and prior
Windows XP Professional x64 Edition SP2 and prior
Windows Server 2003 SP2 and prior
Windows Server 2003 x64 Edition SP2 and prior
Windows Server 2003 with SP2 and prior for Itanium-based Systems
Windows Vista SP1 and prior
Windows Vista x64 Edition SP1 and prior
Windows Server 2008 for 32-bit Systems
Windows Server 2008 for x64-based Systems
Windows Server 2008 for Itanium-based Systems
Exploits of this vulnerability do not require any user interaction. The systems most at risk for exploit are workstations and servers that allow access to Server services through host-based firewalls. All systems hold the same risk, regardless of the affected operating system, as the Server service on each affected version runs with SYSTEM privileges.
An unauthenticated, remote attacker could exploit this vulnerability on Windows 2000, Windows XP, and Windows Server 2003 systems to execute arbitrary code. Microsoft rates this vulnerability as critical on these systems. However, on Windows Vista and Windows Server 2008, the rating is important because the attacker must have authenticated access to the targeted network, reducing the likelihood of attacks on these systems.
Default configurations of Windows XP SP2/SP3, Windows Vista, and Windows Server 2008 protect the RPC interface with the Windows Firewall. However, if the Windows Firewall is disabled, or if file or printer sharing has been enabled, the system will still be vulnerable to an attack.
The compromise of a Windows Server system fulfilling the role of an Active Directory domain controller could allow an attacker to gain access to the stored credentials of user accounts within the domain. If an attacker could retrieve and decrypt those credentials, the attacker could gain access to other resources within the affected site.
Exploit code is publicly available, and the Troj/Gimmiv-A worm is also actively exploiting this vulnerability to install itself on target systems. Additional information on the worm is available in IntelliShield Alert 16947.
Microsoft corrects this vulnerability by improving the way the Server service handles RPC requests.
Microsoft has released a security bulletin at the following link: MS08-067
US-CERT has released a vulnerability note at the following link: VU#827267
An unauthenticated, remote attacker could exploit this vulnerability to cause a DoS condition or execute arbitrary code with privileges of the Server service. Because this service runs under the Local System account, an exploit could allow the attacker to gain complete control over the affected system.
The compromise of an Active Directory domain controller could allow the attacker to gain access to encrypted user credential information that, if decrypted, could allow the attacker to gain access to other computers or resources within the compromised domain.
This vulnerability exists due to insufficient validation of input by netapi32.dll of the Server service. This service provides remote computers access to file and print services and is responsible for named pipes and other communication channels to support RPC.
An unauthenticated, remote attacker could exploit the vulnerability by submitting a specially crafted RPC request to the affected service. This action could trigger an error condition that could allow the attacker to execute arbitrary code with the Local System privileges of the Server service.
Administrators are advised to apply the appropriate updates.
Administrators may consider disabling the Server and Computer Browser services to prevent this vulnerability from being exploited remotely. However, the disabling of the service may greatly reduce the functionality of affected systems, preventing the use of many remote network services.
On Windows Vista and Windows Server 2008, administrators are advised to block all RPC requests with the Universally Unique Identifier (UUID) equal to 4b324fc8-1670-01d3-1278-5a47bf6ee188. Administrators can filter the RPC UUID via the network shell. Details on the specific commands used are in the bulletin.
Administrators may consider blocking TCP ports 139 and 445 at the firewall; however, this may cause the applications using these ports to not function properly. A list of applications using these affected ports is available in the bulletin.
Administrators are advised to protect affected systems from external attacks using a solid firewall strategy.
As a temporary workaround, administrators may consider modifying ACLs for named pipes that are associated with the RPC interface. These ACLs will revert to their default settings each time Windows restarts.
Administrators are advised to restrict access to affected systems.
Administrators are advised to monitor critical systems.
Administrators are advised to employ and update anti-virus applications to prevent malicious software that may attempt to exploit this vulnerability.
Administrators are advised to employ host-based intrusion prevention software to prevent network connections that are established in attempts to exploit this vulnerability.
Microsoft has released updated software at the following links:
Version 2, October 23, 2008, 3:51 PM: Microsoft has released additional technical details to describe the remote procedure call request handling code execution vulnerability in the Microsoft Windows Server service. Cisco has released an applied mitigation bulletin.
Version 1, October 23, 2008, 1:28 PM: Microsoft Windows contains a vulnerability in the Server service that could allow an unauthenticated, remote attacker to create a denial of service condition or execute arbitrary code. Updates are available.
Datacenter Edition Base | Datacenter Edition, 64-bit Base | Itanium-Based Systems Edition Base | Enterprise Edition Base | Enterprise Edition, 64-bit Base | Standard Edition Base | Standard Edition, 64-bit Base | Web Server Base | Web Server, 64-bit Base
Home Basic Base, SP1 | Home Premium Base, SP1 | Business Base, SP1 | Enterprise Base, SP1 | Ultimate Base, SP1 | Home Basic x64 Edition Base, SP1 | Home Premium x64 Edition Base, SP1 | Business x64 Edition Base, SP1 | Enterprise x64 Edition Base, SP1 | Ultimate x64 Edition Base, SP1
Home Edition Base, SP1, SP2, SP3 | Professional Edition Base, SP1, SP2, SP3 | Professional x64 (AMD/EM64T) Base, SP2
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