Microsoft Internet Information Services contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code. Updates are available.
Description
Microsoft Internet Information Services (IIS) versions 6.0, 7.0, and 7.5 contain a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code.
The vulnerability is due to errors in processing malformed HTTP requests. An unauthenticated, remote attacker could exploit this vulnerability by sending an HTTP request to the targeted server. If successful, the attacker could execute arbitrary code with the privileges of the IIS service.
Microsoft has confirmed this vulnerability in a security bulletin and released software updates that correct it.
Warning Indicators
Microsoft IIS versions 6.0, 7.0, and 7.5 are vulnerable when running on the following systems:
Windows Server 2003 SP2 and prior
Windows Server 2003 x64 Edition SP2 and prior
Windows Vista SP2 and prior
Windows Vista x64 Edition SP2 and prior
Windows Server 2008 for 32-bit Systems SP2 and prior
Windows Server 2008 for x64-based Systems SP2 and prior
Windows 7 for 32-bit Systems
Windows 7 for x64-based Systems
Windows Server 2008 R2 for x64-based Systems
Windows Server 2008 R2 for Itanium-based Systems
IntelliShield Analysis
Only IIS servers with the Extended Protection for Authentication module installed are vulnerable to exploitation. The feature is an optional installation.
To exploit the vulnerability, an attacker would have to send a malicious HTTP request to the targeted system. Web servers with public-facing content are most exposed to exploitation.
An exploit could allow the attacker to execute code and take actions on the system in the security context of the limited-privilege Network Service account. The attacker could modify web content on the web server and gain control over any sites served by the web server. Complete system compromise is unlikely in most configurations.
The Cisco Applied Intelligence team has created an Applied Mitigation Bulletin to address vulnerabilities that Microsoft disclosed in the June 2010 security bulletin release. This Cisco bulletin, which assists administrators in identifying or mitigating these vulnerabilities using Cisco devices, is available at the following link: Cisco Applied Mitigation Bulletin: Microsoft Security Bulletin Release for June 2010
Vendor Announcements
Microsoft has released a security bulletin at the following link: MS10-040
Impact
An unauthenticated, remote attacker could exploit this vulnerability to execute arbitrary code with the privileges of the IIS service account.
Technical Information
The vulnerability is due to errors in processing malformed authentication requests. The processing of a malicious authentication request could cause IIS to perform incorrect memory allocation, corrupting memory.
An unauthenticated, remote attacker could exploit this vulnerability by sending a malicious authentication request to the targeted system. When processed, the request could cause memory corruption that the attacker could use to execute arbitrary code with the privileges of the IIS service account, typically Network Service.
Safeguards
Administrators are advised to apply the appropriate updates.
Administrators may consider setting IIS Extended Protection token checking to Require. This configuration setting allows only clients that have implemented Extended Protection to authenticate, which may be unsuitable for some environments.
Administrators are advised to restrict network access to trusted hosts.
Administrators are advised to monitor critical systems.
Patches/Software
Microsoft customers can obtain updates directly by using the links in the security bulletin. These updates are also distributed by Windows automatic update features and available on the Windows Update website. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
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