mailing list archives
MSN Messenger reveals your name to websites (and can reveal email addresses too)
From: Richard Burton <richardaburton () hotmail com>
Date: 2 Feb 2002 20:39:16 -0000
MSN Messenger (and Windows Messenger on XP)
can be used to obtain personal information about a
user from any website (in any domain).
obtained from Messenger, as well as the display
names of all their contacts. For users who have a
sensible and accurate display name this should be
considered a privacy issue. (Note: anyone who has
not set a display name at all, will reveal their email
Using the same technique web sites hosted on
certain domains (microsoft.com, hotmail.com &
hotmail.msn.com) can also access the email
address of the user (along with the email addresses
of all their contacts). This could be used by Microsoft
to track users on their sites, which many would
consider to be a privacy issue.
In addition to the three domains mentioned above,
additional domains can be allowed access to the
email addresses with a single registry entry. This
registry entry could be made by spyware/adware
installed by a user (sometimes unknowingly along
with a piece of shareware). Once there you have the
potential to give your email address to any site that
requests it and places it in a cookie.
- MSN Messenger 4.6.0073 (latest at 02/02/2002) on
Windows 2000 with IE 6.
- Windows Messenger 4.6.0073 (latest at
02/02/2002) on Windows XP with IE 6.
- Probably other versions and other platforms too.
Microsoft designed Messenger to allow functionality
VBScript. This includes the ability to view the display
name and email address of the user and their
contacts. In an attempt to protect users only a certain
selection of sites can use script to get email
addresses, but all can get display names.
The list of domain suffixes that have full access to
Messenger functionality (email addresses & more?)
can be found in the registry in
Values "Suffix0", "Suffix1", etc. By default there are no
entries in the list, but they can be added. E.g. adding
value Suffix0 = "test.com" will give web sites in the
test.com domain full access to Messenger
Full domains do not have to be specified in the list,
adding "com" would allow all .com sites to have full
Although by default there are no entries in this list,
three domains (listed above) are hard coded into
Messenger for the same purpose. These allow
Microsoft to make their sites (e.g. Hotmail) look nice
by integrating messenger features into them. The
user cannot remove the special status applied to
The only way for a user to prevent sites having any
access to their information is by logging out of
Messenger before visiting.
For a simple how-to, just look at the source of the
demonstration page given below.
I have set up a simple demonstration of the problem
This will show your name and the names of all your
contacts. If you add the registry entry given it will also
show your email address and the addresses of all
Recommendations For Users
- Set a display name so your email address isn't
obtainable so easily.
- Check for entries
especially after installing freeware or shareware.
- If you want to visit microsoft.com and remain
anonymous, close MSN Messenger.
Recommendations For Microsoft
- Remove the hard coded list of domains, so users
can choose to allow this functionality on MS sites.
- Prevent applications adding to the Suffixes list.
- Give the user the option to disable the scripting
Richard Antony Burton - richardaburton () hotmail com
Please feel free to contact me about this post, I will
do my best to answer any questions you may have.
- MSN Messenger reveals your name to websites (and can reveal email addresses too) Richard Burton (Feb 05)