Re: [Exim] Bad Authentication ACL, used for relay - 4.20

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Autor: John Jetmore
Datum:  
To: Chris Huff
CC: exim-users
Neue Treads: [Exim] Master basic mail filters/.forward file
Betreff: Re: [Exim] Bad Authentication ACL, used for relay - 4.20
On Wed, 10 Sep 2003, Chris Huff wrote:

> auth_login:
> driver = plaintext
> public_name = LOGIN
> server_condition = "${if eq {${lookup{$1}lsearch{/usr/local/exim4/exim.passwd}{$value}}} {$2} {yes} {no}}"
> server_set_id = $1
> server_prompts = "Username:: : Password::"


Isn't this the classic non-existant user, empty password vulnerability?
(looking up the passwd for a non-existant user yields an empty string. If
an empty string is provided as the user's password, the two strings match
and relaying is allowed). Looking at the mainlog entries for the relays
would probably tell you whether the authenticator is being abused or
something else.

--John