Re: [exim] tainted data issues

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Autor: Andrew C Aitchison
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A: Sebastian Nielsen
CC: Mailing List
Assumpte: Re: [exim] tainted data issues
On Wed, 11 Nov 2020, Sebastian Nielsen via Exim-users wrote:

> Yes, but its a positive match only - meaning you have to explicitly
> specify allowed characters.The function should NOT be able to
> specify forbidden characters - as then it would ve easy to miss bad
> characters.If an sysadmin then writes a filter which is too broad -
> its his own fault.


Even that has pitfalls once you add non-ascii characters.

> I mean - I have a Email-to-sms gateway which pipes
> data to a system script.<number>@sebbe.eu is interpreted as outgoing
> SMS.With the current structure, you need to add every number you
> want to SMS as whitelist - as you need to do a successful lookup to
> untaint.Its much better to be able to specify that localpart can
> only contain numbers to be permitted to be piped to the script - no
> security risk as nobody can escape out of a shell command with only
> 0-9 to their disposal.


I wonder whether a specific "telephone number" option would make sense ?
Do we allow the international code "+", or the pause (which can be
used in fax numbers)
https://www.dummies.com/consumer-electronics/smartphones/droid/how-to-add-pauses-when-dialing-a-number-on-your-android-phone/ ?

-- 
Andrew C. Aitchison                    Kendal, UK
             andrew@???