Yahoo Pager - security bug w/ services 7,8

[nneul () UMR EDU (Nathan Neulinger)]

I've been working on a GTK (unix) yahoo pager client based on Doug
Winslow's yppro2.c source and found the following security problem while
testing some client functionality.

Any user can send a packet with service #7 or #8 and activate/deactivate
an identity, even if it isn't your own alternate identity. It does
appear that the primary id for the identity affected has to be logged on
though.

If you send a message to that id, it does go to the correct destination.

The problem is, it can be abused simply by someone logging on and
deactivating an identity for someone else, which makes it look like that
id logged off.

The fix - when your server handles a id-activate/id-deactivate service
request, it should make sure that request is coming from the primary ID
for that identity. (You should be able to do that without a protocol
version change.)

-- Nathan