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TUCoPS :: Windows :: bt141.txt

Multiple Vulnerabilities found in Microsoft .Net Passport Services

PakCERT Security Advisory PC-080503
Multiple Vulnerabilities found in Microsoft .Net Passport Services
May 08, 2003


“Microsoft® .NET Passport is a Web-based service designed to make
signing in to Web sites fast and easy. .NET Passport enables
participating sites to authenticate a user with a single set of sign-in
credentials, eliminating the need for users to remember numerous
passwords and sign-in names.”

“Since its launch in 1999, Microsoft® .NET Passport has become one of
the largest online authentication systems in the world, with more than
200 million accounts performing more than 3.5 billion authentications
each month. .NET Passport participating sites include NASDAQ, McAfee,, eBay, Cannon, Groove, Starbucks, MSN® Hotmail, MSN
Messenger, and many more.”

Benefits of Using .Net Passport Services

• “Use one name and password to sign in to all .NET
Passport-participating sites and services.”

• “Store personal information in your .NET Passport profile and, if you
choose, automatically share that information when you sign in so that
participating sites can provide you with personalized services.”


PakCERT has discovered two serious vulnerabilities in Microsoft .Net
Passport Services, which if exploited, affects over 200 million users
worldwide. Using these vulnerabilities and the single sign-in feature of
Microsoft .Net Passport, an attacker can completely take control of a
user’s account including Hotmail email account, personal information,
credit card numbers, shopping lists etc and use it on any of the .Net
Passport participating web sites.

Issue One: Bypass Security Questions

An attacker can bypass the security questions asked before resetting the
password. When Microsoft Hotmail/.Net Passport users forget their
passwords, they have to fill out a web form that requires their email
address, state, zip code and country. After submitting the correct
information users are prompted to answer the secret question they
entered during their signup for the service.

As a result of this vulnerability, Microsoft Hotmail/.Net Passport users
who rely on questions like “What’s my name?” or “What’s my favorite
color?” could find themselves loosing their accounts.

Issue Two: Password Reset Vulnerability

An attacker can reset any Microsoft Hotmail/.Net Passport user account
with no prior information like state, zip, country, answer to the secret
question and the old password. Normally, a user has to answer the
security questions and than answer the secret question if he wants to
reset his password. By exploiting this vulnerability, an attacker can
submit a specially crafted URL to get the password reset instructions
and reset any user’s password.


Due to the nature of this vulnerability and the fact that there is no
fix available yet, no technical details are being made available with
this advisory. Full technical details will be made available on our
website once the vulnerability is fixed by Microsoft. Please note that
we were forced to release this information public as these
vulnerabilities are actively being exploited in the wild and are one of
the most severe vulnerabilities ever found in Microsoft Hotmail/.Net

FOUND BY:  Qazi Ahmed & Shoaib Rehman

AUTHOR:  Qazi Ahmed


The information within this paper may change without notice. Use of this
information constitutes acceptance for use in an AS IS condition. There
are NO warranties with regard to this information. In no event shall the
author be liable for any damages whatsoever arising out of or in
connection with the use or spread of this information. Any use of this
information is at the user's own risk.

PakCERT Contact Information:

 Phone: +92-21-5872445 – 47
 Fax:   +92-21- 5378505
 Postal Address:
 Office #5, 3rd Floor, Plot No. 6-C
 7th Zamzama Commercial Lane
 Phase-V, D.H.A
 Karachi, Pakistan


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