Microsoft Security Advisory (2876146)
Wireless PEAP-MS-CHAPv2 Authentication Could Allow Information Disclosure
Microsoft is aware of a public report that describes a known weakness in the Wi-Fi authentication protocol known as PEAP-MS-CHAPv2 (Protected Extensible Authentication Protocol with Microsoft Challenge Handshake Authentication Protocol version 2), used by Windows Phones for WPA2 wireless authentication. In vulnerable scenarios, an attacker who successfully exploited this issue could achieve information disclosure against the targeted device. Microsoft is not currently aware of active attacks or of customer impact at this time. Microsoft is actively monitoring this situation to keep customers informed and to provide customer guidance as necessary.
To exploit this issue, an attacker controlled system could pose as a known Wi-Fi access point, causing the targeted device to automatically attempt to authenticate with the access point, and in turn allowing the attacker to intercept the victim's encrypted domain credentials. An attacker could then exploit cryptographic weaknesses in the PEAP-MS-CHAPv2 protocol to obtain the victim's domain credentials. Those credentials could then be re-used to authenticate the attacker to network resources, and the attacker could take any action that the user could take on that network resource.
Recommendation. Apply the suggested action to require a certificate verifying a wireless access point before starting an authentication process. Please see the Suggested Actions section of this advisory for more information.
This advisory discusses the following devices.
|Affected Device Operating System|
|Windows Phone 8|
|Windows Phone 7.8|
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- 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 4, 2013): Advisory published.