Author: David Woodhouse Date: To: Sandro Tosi CC: exim-dev Subject: Re: [exim-dev] Remote root vulnerability in Exim
On Mon, 2010-12-13 at 16:21 +0100, Sandro Tosi wrote: > We have a 4.69 custom installation, so I tried to replicate the exploit
> at  but without success (FSVO it ;).
>  http://seclists.org/fulldisclosure/2010/Dec/222 >
> we have set 'message_size_limit = 100M' and the attack stops with a
> 552 Message size exceeds maximum permitted
> and log entry:
> 2010-12-13 11:50:06  1PS5yL-0005o8-R7 rejected from
> <root@???> H=(abcde.com) [18.104.22.168]: message too big:
> read=105155021 max=104857600
> is this mean that the attack needs to send more than 100M of data and so
> our config is "safe"?
The body size has nothing to do with it. Personally I tweaked it down to
1MiB on my test box to speed up testing.
It's the size of the *headers* which does it. Your initial headers need
to precisely reach the end of the log buffer in order to trigger the
> If some unlucky guy is in a position that cannot check how a given exim
> installation was compiled, is there a way to know if
> ALT_CONFIG_ROOT_ONLY was set or not at build time?
Create a config file in /tmp, and as the Exim user try running
exim -C /tmp/myconfig
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