Re: php - inject code into $_SERVER ?

I would highly recommend using a regular expression to only accept 
xxx.xxx.xxx.xxx

On Feb 1, 2005, at 4:16 AM, Christophe Vandeplas wrote:

> Hello
>
> I am coding a kind of weblogin system that adapts the firewall of a
> gateway for logged users so that they can access another network.
> The weblogin system is written in php4 on a apache2 webserver running 
> on a debian system.
>
> to adapt the firewall I made a simple script, let's call it
> firewallAuth. This script needs 1 argument, the ip that needs to be
> added in the firewall.
>
> Now the only way to do this in php is to use the 'exec()' function.
> The ip of the user is stored in $_SERVER['REMOTE_ADDR'].
> To get root rights (I need them to adapt my firewall) i use sudo. (the
> php user can only run the firewallAuth command with sudo)
>
> So I just do this in php code:
> exec("sudo /home/firewall/firewallAuth ".$_SERVER['REMOTE_ADDR']);
>
> My question is now: is there any (known) way for a user to inject 
> arbitrary code
> into this _SERVER global? (and thus execute this code on the server 
> with root permissions)
> or am I not-to-unsafe to use it?
>
> Should I perform some more checks on the $_SERVER['REMOTE_ADDR'] 
> before using it as argument?
>
>
> Thanks for the comments.
>
>
> -- 
> -------------------------------------
> Christophe Vandeplas
> GSM: +32 (0)486/64.10.33
> email: christophe(at)vandeplas(dot)com
> http://www.vandeplas.com
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> 3897
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> -- 
> -------------------------------------
> Christophe 'ElCascador' Vandeplas
> GSM: +32 (0)486/64.10.33
> email: christophe(at)vandeplas(dot)com
> http://www.vandeplas.com
> GnuPG:1024D/14913897: 66BD A9EB 0357 D80F 20D4  D698 3B2B E562 1491 
> 3897
> -------------------------------------
> *** PLEASE ***
> "Never send mass-mails/forward to this email address.
>  Please add the email-address to the BCC field (Blind Carbon Copy)
>  or send the mail separately to me."