Re: PPP/ISDN multilink security issue - summary

[marc () SNAFU ORG (Marco S Hyman)]

David Schwartz writes:
> Ascend has stated (unofficially) that their implementation was at one point
> insecure, and relied upon the TEI or EDO (endpoint identifier) to make the
> decision. This is in violation of standards. They state that their
> implementation has been secure for about three years and will not bond two
> connections together unless the authenticate with the same username.

1) TEI is an ISDN thing.  Perhaps you have confused the ISDN term TEI
   (Terminal Endpoint Identifier) with the PPP term Endpoint Descriminator.
   They are NOT the same thing.  The PPP code knows nothing about the ISDN
   TEI.  It can't as PPP is not dependent upon ISDN.

2) Ascend code would add a link to an existing bundle if the Endpoint
   Descriminator matched AND the link was authenticated.  The bug
   was that the authenticated user did not have to match the bundle's
   user.  Yes, that was incorrect.  Yes, it would cause a DoS.  However,
   since the caller causing the DoS had to be authenticated (and was
   logged) it was easy to see who was causing problems and trivial to
   disable that login.  But it's good to hear that the problem has
   been fixed.

// marc