Microsoft Security Advisory (2743314)
Unencapsulated MS-CHAP v2 Authentication Could Allow Information Disclosure
Microsoft is aware that detailed exploit code has been published for known weaknesses in the Microsoft Challenge Handshake Authentication Protocol version 2 (MS-CHAP v2). The MS-CHAP v2 protocol is widely used as an authentication method in Point-to-Point Tunneling Protocol (PPTP)-based VPNs. Microsoft is not currently aware of active attacks that use this exploit code or of customer impact at this time. Microsoft is actively monitoring this situation to keep customers informed and to provide customer guidance as necessary.
- Only VPN solutions that rely on PPTP in combination with MS-CHAP v2 as the sole authentication method are vulnerable to this issue.
Recommendation. Please see the Suggested Actions section of this advisory for more information.
For more information about this issue, see the following references:
|Microsoft Knowledge Base Article||2744850|
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- Customers in the United States and Canada can receive technical support from Security Support. For more information, see Microsoft Help and Support.
- International customers can receive support from their local Microsoft subsidiaries. For more information, see International Support.
- Microsoft TechNet Security provides additional information about security in Microsoft products.
The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
- V1.0 (August 20, 2012): Advisory published.