preventing a user to start a process

[Gustavo A. Baratto]

ps aux | grep www | grep -v /usr/local/bin/httpd

The above returns all processes that user www is running, that are not 
apache itself.

You can use some perl to split the lines to find out how long the processes 
have been running based on the STARTED column of the command above. If I had 
such code ready, I'd just send to you, but unfortunately I dont.

Cheers.

----- Original Message ----- 
From: "Thomas Krause" <freebsd-isp at chef-ingenieur.de>
To: <freebsd-isp at freebsd.org>
Sent: Tuesday, July 26, 2005 1:44 PM
Subject: Re: preventing a user to start a process


>
>
> Gustavo A. Baratto schrieb:
>> Although jailing is a good thing, I don't think it will prevent unwanted 
>> processes to be spawned, if php allows it. And having writable 
>> directories mounted noexec doesn't help much either, because one can just 
>> run:
>> /usr/bin/sh /path/to/writable/dir/script.sh
>>
>> Since most of the times script kiddies use /tmp or /var/tmp (which are 
>> usually noexec) to upload their scripts, the sh or perl binaries are 
>> located in file systems that allow execution.
>>
>> So, you can either tell php not to spawn processes (safe_mode or 
>> disable_functions), or to have all file systems in contact with php 
>> mounted noexec (not just the writable directories). This will probably 
>> make your life hell. Or even disallow any kind of uploads in php (which 
>> is not very effective against code execution, as a bug in your code could 
>> allow execution like phpBB exploit a while ago).
>>
>> If you cannot do any of these because you require the functionality, you 
>> can write a cron'ed script that checks for processes owned by www that 
>> are running for a certain period of time and are not the apache. You can 
>> either kill these processes or e-mail yourself, and then you take an 
>> action.
>
> I think, I should do so. But how to identify the process? The ircd
> was renamed to "sh", to make it harder to find in the process list.
> It should be possible with the PGID (from /var/run/httpd.pid) and
> the UID. Does anyone know a usable (or recyclable) script for that
> job?
>
> Regards,
> Thomas.
>
>
>>
>> Cheers
>>
>> ----- Original Message ----- From: "Adam Jacob Muller" <adam at oxeo.com>
>> To: "Thomas Krause" <freebsd-isp at chef-ingenieur.de>
>> Cc: "David Hogan" <david at fundamentalit.com>; <freebsd-isp at freebsd.org>; 
>> "'Gustavo A. Baratto'" <gbaratto at superb.net>
>> Sent: Tuesday, July 26, 2005 9:59 AM
>> Subject: Re: preventing a user to start a process
>>
>>
>>> Pretty much the only "secure" option is to either
>>> A.    run in a chroot jail
>>> B.    run with any writable directories mounted noexec
>>> or if your really paranoid, do both
>>>
>>> Adam
>>>
>>>
>>> On Jul 26, 2005, at 12:49 PM, Thomas Krause wrote:
>>>
>>>>
>>>>
>>>> David Hogan schrieb:
>>>>
>>>>>> -----Original Message-----
>>>>>> From: owner-freebsd-isp at freebsd.org [mailto:owner-freebsd- 
>>>>>> isp at freebsd.org]
>>>>>> On Behalf Of Thomas Krause
>>>>>>
>>>>>
>>>>>
>>>>>> I've searched all php-files for the system()-funktion - it's not
>>>>>> possible for me do disable this function.
>>>>>>
>>>>> Can't you just use the 'disable_functions =' option in php.ini to 
>>>>> disable
>>>>> the php functions that can be used to spawn processes ?
>>>>> You could use it to disable at least the following functions:
>>>>> system()
>>>>> exec()
>>>>> passthru()
>>>>> popen()
>>>>> pcntl_exec()
>>>>> shell_exec()
>>>>>
>>>>
>>>> Unfortunately, that is not possible. E.g. typo3 calls Imagemagick,  so 
>>>> I need system().
>>>>
>>>> Regards,
>>>> Thomas.
>>>> _______________________________________________
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>>>
>>
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