Bug#403605: exim4-config: dc_other_hostnames expanded by the shell, corrupting it

[Marc Haber]

package exim4-config
severity #403605 important
thanks

On Mon, Dec 18, 2006 at 12:41:27PM +0100, Paul Slootman wrote:
> Package: exim4-config
> Version: 4.63-11
> Severity: grave
> Justification: email was bounced, thus lost to me

Bounced e-mail is not lost. Downgrading.

> I have a wildcard MX *.wurtel.net, and that's filled in
> /etc/exim4/update-exim4.conf.conf accordingly:
> 
> dc_other_hostnames='wurtel.net : *.wurtel.net : ...'

not supported, dc_other_hostnames is a list of semicolon-separated
domain names. No wildcards here.

> However, I noticed once that instead of *.wurtel.net, the generated
> config file had db.wurtel.net.  At the time I passed that off as an
> error on my part, as when running update-exim4.conf again it was
> correct.
> 
> Today I again noticed in the exim logs that a lot of mail was being
> bounced due to "relay not permitted". Again I saw db.wurtel.net instead
> of *.wurtel.net, and now I was sure I hadn't made any mistake.
> 
> Upon investigation it appeared that if a file exists in the current
> directory that matches *.wurtel.net when update-exim4.conf is run, the
> filename is filled into the config file, hence corrupting it :-(
> update-exim4.conf echoes the value of dc_other_hostnames without any
> quoting!
> 
> I could imagine that this might even be used to bypass security if a
> malicious user could get an admin to run update-exim4.conf in a
> directory with specially prepared filenames.
> 
> I recommend that a fix is included in the version that's to go into
> etch.

Agreed. Be warned, however, that we might fix this by forbidding * and
? in ue4.conf.conf by means of replacing them with "_" after giving a
warning. Better move your wildcard to the macros made available inside
exim configuration.

Greetings
Marc

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