OSEC

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From: Joel Maslak (jmaslakantelope.net)
Date: Wed Feb 06 2002 - 19:47:37 CST

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    On Tue, 5 Feb 2002, E M wrote:

    > .: Problem :.
    > While Intel requires you to login to modify account information, it does not
    > require you to login to remove your e-mail (or any e-mail) from its mailing
    > list database.

    This is nothing new.

    The web interface is new, but being able to remove users from mailing
    lists without any verification is not.

    Many mailing lists - especially large volume ones - will remove any
    address that bounces. Creating a forged bounce request is quite trivial.

    The fix for this requires sophisticated bounce tracking software. The
    only real way to fix this problem is to send each recipient a message with
    a custom-encoded FROM envelope address, such as:
            bounce-<user-id>-<security-key>example.com
    Where the user-id is some sort of database identifyer and the security key
    is simply a random number kept in the database to prevent malicious
    activity (it could also be some sort of cryptographic code). When the
    example.com mail server receives a message to bounce-xxx-yyyexample.com,
    it checks the security key, verifies that the bounce is a permanent
    bounce, and deletes the user.

    You can also do something similar with WWW removal links:
            Click http://remove.example.com/>/<security-key>

    Most mass mailing systems don't do any of this, though, since this
    requires sending a unique message to every recipient. Instead of sending
    one body with lots of envelope addresses to, say, AOL, you end up sending
    lots of complete messages - including duplicate copies of the body - to
    AOL.

    -- 
    Joel Maslak