Vulnerability identifier: #VU2747

Vulnerability risk: High

CVSSv3.1: 5.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L/E:F/RL:O/RC:C]

CVE-ID: CVE-2009-1536

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Windows
Operating systems & Components / Operating system
Windows Server
Operating systems & Components / Operating system
Microsoft .NET Framework
Server applications / Frameworks for developing and running applications

Vendor: Microsoft

Description
The vulnerability allows a remote attacker to cause DoS conditions on the target system.

The weakness exists due to incorrect managing of request scheduling by ASP.NET. By sending multiple HTTP requests, a remote attacker can trigger the Web server to crash.

Successful exploitation of the vulnerability results in denial of service on the vulnerable system.

Note: the vulnerability was being actively exploited.

Mitigation
Install update from vendor's website:

Windows Vista:
Microsoft .NET Framework 2.0 Service Pack 1 and Microsoft .NET Framework 3.5:
https://www.microsoft.com/downloads/details.aspx?familyid=d42444bb-5030-4b47-87fa-9df3a8c640ff
Microsoft .NET Framework 2.0 Service Pack 2 and Microsoft .NET Framework 3.5 Service Pack 1:
https://www.microsoft.com/downloads/details.aspx?familyid=310f3aa6-c264-45a2-b24a-3f178b41830e
Microsoft .NET Framework 2.0 Service Pack 1 and Microsoft .NET Framework 3.5:
https://www.microsoft.com/downloads/details.aspx?familyid=cbf40800-f3b3-43da-ace1-d942d3378ccd
Microsoft .NET Framework 2.0 Service Pack 2 and Microsoft .NET Framework 3.5 Service Pack 1:
https://www.microsoft.com/downloads/details.aspx?familyid=87c4a868-b3b5-467d-96a4-633532ab548f
Microsoft .NET Framework 2.0 Service Pack 1 and Microsoft .NET Framework 3.5:
https://www.microsoft.com/downloads/details.aspx?familyid=d42444bb-5030-4b47-87fa-9df3a8c640ff
Microsoft .NET Framework 2.0 Service Pack 2 and Microsoft .NET Framework 3.5 Service Pack 1:
https://www.microsoft.com/downloads/details.aspx?familyid=310f3aa6-c264-45a2-b24a-3f178b41830e
Microsoft .NET Framework 2.0 Service Pack 1 and Microsoft .NET Framework 3.5:
https://www.microsoft.com/downloads/details.aspx?familyid=cbf40800-f3b3-43da-ace1-d942d3378ccd
Microsoft .NET Framework 2.0 Service Pack 2 and Microsoft .NET Framework 3.5 Service Pack 1:
https://www.microsoft.com/downloads/details.aspx?familyid=87c4a868-b3b5-467d-96a4-633532ab548f

Windows Server 2008:
Microsoft .NET Framework 2.0 Service Pack 1 and Microsoft .NET Framework 3.5:
https://www.microsoft.com/downloads/details.aspx?familyid=cbf40800-f3b3-43da-ace1-d942d3378ccd
Microsoft .NET Framework 2.0 Service Pack 2 and Microsoft .NET Framework 3.5 Service Pack 1:
https://www.microsoft.com/downloads/details.aspx?familyid=87c4a868-b3b5-467d-96a4-633532ab548f
Microsoft .NET Framework 2.0 Service Pack 1 and Microsoft .NET Framework 3.5:
https://www.microsoft.com/downloads/details.aspx?familyid=cbf40800-f3b3-43da-ace1-d942d3378ccd
Microsoft .NET Framework 2.0 Service Pack 2 and Microsoft .NET Framework 3.5 Service Pack 1:
https://www.microsoft.com/downloads/details.aspx?familyid=87c4a868-b3b5-467d-96a4-633532ab548f

Vulnerable software versions

Windows: Vista

Windows Server: 2008

Microsoft .NET Framework: 2.0, 3.5

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External links
http://technet.microsoft.com/en-us/library/security/ms09-036.aspx

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, a fully functional exploit for this vulnerability is available.