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Vulnerability Alert

Microsoft .NET Framework HTTP Request Processing Denial of Service Vulnerability

 
Threat Type:CWE-399: Resource Management Errors
IntelliShield ID:18769
Version:1
First Published:2009 August 11 17:47 GMT
Last Published:2009 August 11 17:47 GMT
Port: Not available
CVE:CVE-2009-1536
Urgency:Unlikely Use
Credibility:Confirmed
Severity:Mild Damage
CVSS Base:5.0 CVSS Calculator
CVSS Version 2.0
CVSS Temporal:3.7
Related Resources:
View related IPS Signature
 
 
Version Summary:

Microsoft Windows contains a vulnerability within the .NET Framework that could allow an unauthenticated, remote attacker to cause a denial of service condition.  Updates are available.

 
 
Description

Microsoft Windows contains a vulnerability within the .NET Framework that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.

This vulnerability exists due to errors in managing request scheduling by the ASP.NET component.  An unauthenticated, remote attacker could exploit this vulnerability by sending malicious HTTP requests to the vulnerable system.  If successful, the attacker could cause the web service to become unresponsive, resulting in a DoS condition.

Microsoft has confirmed this vulnerability in a security bulletin and released software updates that correct it.

 
Warning Indicators

The following Microsoft systems are vulnerable when running Internet Information Services (IIS) version 7.0 and the .NET Framework versions 2.0 SP2 and prior and 3.5 SP1 and prior in integrated mode:

  • Windows Vista SP1
  • Windows Vista x64 Edition SP1
  • Windows Server 2008 for 32-bit Systems
  • Windows Server 2008 for x64-based Systems
  • Windows Server 2008 for Itanium-based Systems
 
IntelliShield Analysis

Because systems running .NET components as part of IIS are commonly exposed to the Internet or other publicly accessible networks, the source of potential attacks may be very large, increasing the chance of exploitation.  However, only systems in certain configurations are affected, possibly making some sites immune to exploits.

If an exploit is successful, the IIS service may become unresponsive to further requests.  However, the underlying operating system is unaffected, and still functions normally.  Administrator intervention is required to restart the IIS service or application pool in order to restore proper functionality.

The Cisco Applied Intelligence team has created an Applied Mitigation Bulletin to address vulnerabilities that Microsoft disclosed in the August 2009 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 August 2009 

The update available from Microsoft corrects this vulnerability by modifying ASP.NET request scheduling.

 
Vendor Announcements

Microsoft has released a security bulletin at the following link: MS09-036

 
Impact

An unauthenticated, remote attacker could exploit this vulnerability to cause IIS to become unresponsive, resulting in a DoS condition.

 
Technical Information

This vulnerability exists due to errors in managing request scheduling by the ASP.NET component.  Only systems using the .NET Framework running in integrated mode is affected.  An unauthenticated, remote attacker could exploit this vulnerability by sending a series of malicious HTTP requests to the vulnerable system.  When processed, the requests could cause an error condition that causes the IIS service to become unresponsive, resulting in a DoS condition.  However, the underlying operating system is unaffected.

 
Safeguards

Administrators are advised to apply the applicable software updates.

Administrators may consider configuring the .NET Framework to run in classic mode.

Administrators may consider configuring IIS to use native thread pool process handling.

Administrators are advised to monitor critical systems for service failures.

Administrators may consider using the Microsoft Baseline Security Analyzer (MBSA) scan tool to identify common security misconfigurations and missing security updates on system endpoints.

 
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.


Signatures
 
Cisco Intrusion Prevention System (IPS) 6.0
Signature IDSignature NameReleaseLatest Release Date
20150/0ASP.NET Denial Of ServiceS5272010 Nov 03 
20150/1ASP.NET Denial Of ServiceS6922013 Jan 30 
 
Alert History
 

Initial Release



Product Sets
 
The security vulnerability applies to the following combinations of products.

Primary Products:
Microsoft, Inc..NET Framework 2.0 SP1, SP2 | 3.5 Base, SP1

Associated Products:
Microsoft, Inc.Windows Server 2008 Datacenter Edition Base | Datacenter Edition, 64-bit Base | Itanium-Based Systems Edition Base | Enterprise Edition Base | Enterprise Edition, 64-bit Base | Essential Business Server Standard Base | Essential Business Server Premium Base | Essential Business Server Premium, 64-bit Base | Standard Edition Base | Standard Edition, 64-bit Base | Web Server Base | Web Server, 64-bit Base
Microsoft, Inc.Windows Vista Home Premium Base, SP1 | Business Base, SP1 | Enterprise Base, SP1 | Ultimate Base, SP1 | Home Premium x64 Edition Base, SP1 | Business x64 Edition Base, SP1 | Enterprise x64 Edition Base, SP1 | Ultimate x64 Edition Base, SP1




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The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.
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