RE: virtual server - security

["Dave Paris" <dparis () w3works com>]

comments interspersed below...

Kind Regards,
-dsp

> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Serban Gh. Ghita
> Sent: Tuesday, March 30, 2004 4:05 AM
> To: [EMAIL PROTECTED]
> Subject: [SC-L] virtual server - security
>
>
> Hello
>
> I am banging my head on the table every day, because i cannot find an
> elegant and safe solution to secure a virtual shared environment (server).
> Take the following facts:
[...]
> -no one has acces to shell, cronjobs or stuff like that, only 21 and 80

What's the point of the exercise if you're passing plaintext passwords
across on port 21?  At the very least, mandate SCP/SFTP on port 22.

> -you dont want anyone to get out of his 'box' (eg /home/sasha/)

use 'chroot' jails

> -you want to allow php, perl or other web languages to run safely

"PHP" and "run safely" in the same sentence?  Have you perused Bugtraq
lately?

> and in the
> same time will _almost_ all features.
> -in php (because this is the one of the most user language for web - for
> mostly endusers), i have options like safe_mode, but if i activate that,
> many functions and features will not work. i know (because i tested) that
> the best solution is open_basedir, but i cannot create an restriction like
> that for each user, or at least i dont know how to do that.

That's primarily because PHP will let you shoot yourself in the head, as
opposed to most languages which will only let you shoot yourself in the
foot, or at least no higher than the knee.  (snide commentary... unless it's
a microsoft product, which seem to aim squarely for "the jewels")

> My problem is that i tested some script-kiddies local exploits (php,perl)
> and the system is vulnerable, the user can get out of his box and
> see system
> files (etc/passwd, other dirs).

::feigns shock::

> What are the options here. Any paper or book written about this?

Yes.  Near daily bugtraq reports about why PHP is a darned good idea that
made a left turn into a really bad neighborhood.  The manpage for
SCP/SFTP/SSH.  The manpage for 'chroot'.