Instalat ca modul Apache

Când PHP este utilizat ca modul în Apache, el moşteneşte permisiunile implicite ale Apache (de obicei acelea ale utilizatorului "nobody"). Acest fapt are mai multe impacte asupra securităţii şi autorizării. De exemplu, dacă utilizaţi PHP pentru a accesa o bază de date, şi dacă aceasta nu are control de acces inclus, va trebui să faceti această bază de date să fie accesibilă utilizatorului "nobody". Aceasta înseamnă că un script malefic va putea accesa şi modifica baza de date chiar fără a introduce numele utilizatorului şi parola. Este posibil ca un robot de indexare web să acceseze accidental panoul de administrare al bazei de date şi să modifice sau să şteargă toate datele. Vă puteţi proteja cu ajutorul sistemului de autorizare al Apache, sau printr-un model de acces personalizat folosind LDAP, fişiere tip .htaccess, etc. pe care să le introduceţi în scripturile PHP create.

Adesea, după ce politica de securitate a fost stabilită, iar utilizatorul PHP (în acest caz, utilizatorul Apache) prezintă risc redus faţă de sistem, iese la iveală faptul că PHP este restricţionat în a scrie în fişierele şi directoarele utilizatorilor, sau nu poate accesa şi schimba anumite baze de date. El a fost securizat atât în a scrie fişiere bune, cât şi rele, sau inserarea de tranzacţii atât benefice, cât şi dăunătoare bazelor de date.

O greşeală de securitate frecventă este că atunci când se ajunge în acest moment, să se dea pemisii de root serverului Apache, sau să se extindă permisiunile într-un careva alt mod.

Extinderea privilegiilor utilizatorului Apache către root este deosebit de periculoasă şi poate duce la compromiterea întregului sistem, aşa că operaţiunile 'sudo', 'chroot', sau alte modalităţi de a rula root nu ar trebui luate în considerare în caz că nu sunteţi expert în securitare.

Există şi soluţii mai simple. Utilizând open_basedir puteţi controla şi restricţiona ce directorii doriţi, în care poate avea acces PHP. În plus puteţi stabili zone numai pentru Apache, pentru a preveni toate acţiunile din web asupra fişierelor utilizatorilor şi de sistem.

Filesystem Security

Cazul 4: parserul PHP in afara directorului radacina web

Last updated: Fri, 01 Aug 2008

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Instalat ca modul Apache

Vikanich
14-Aug-2008 02:41


Big thanks to "daniel dot eckl at gmx dot de" but i have to change his config, because it doesn't work (may be wrong syntax).

I have add only this string to VirtualHost config and it works.

php_admin_value open_basedir  /www/site1/

Now all php scripts are locked in the directory.

Kibab
30-Sep-2005 04:56


I'm running Windows version of Apache with php as module. System is Windows XP Service Pack 2 on NTFS filesystem. To avoid potential security problems, I've set Apache to run under NT AUTHORITY\Network Service account, and there is only one directory, named Content, with Full Access for this account. Other directories are either not accessible at all or with readonly permissions (like %systemroot%)... So, even if Apache will be broken, nothing would happen to entire system, because that account doesn't have admin privilegies :)

tifkap
02-Mar-2004 01:21


There is a safe way to support a lot of users in a secure way, without having to use CGI, in a way which is probebly faster

than mod_php.



Use FastCGI, with the SuExecWrapper set to your suid wrapper. It means every user wil get his own program-group, with processes

which are being reused. If the numer of processes that is being 

started on startup is 0, then the processgroup for a user will be generated when needed.



This means: The first page is slow, after that the Zend Engine  caching kicks in. When the load on the virtualhost reduces, the

processes wil die off, and extra processes for a user-process-group 

will only be started when (again) needed.



Your apache will be a LOT! lichter, because it won't have to drag all

the php-memory overhead with it. This means static content is 

faster, and the whole system uses less memory. 

The PHP itself also won't need to drag along the apache overhead.



If for one reason or the other php craches, your apache will simple 

start some new php-processes. If you want to upgrade/patch php, 

you can simple create the new fastcgi binary, and after testing, you can simple update the system by copying it, and maybe doing a 

'apachectl gracefull'



In short :  Sepparating distinct functions in different processes 

                communicating useing IPC methodes can be very good

                for performance and security. The best example of this

                principle at work is Postfix, where every process runs 

                chroot() under its own uid.



http://wiki.openisis.org/i/view/Php/HowtoFastCgi

Georgee at CWC
30-Apr-2003 04:16


Additional CAUTION to anyone trying Pollux's solution:

It's kind a good. Probably works right. I think I'll give it a try myself. BUT...

its safe ONLY on the assumption that apache is 100% CLEAN. (codes and confs.) Any flaws on apache, almost ANYTHING could happen to ALL users -precisely, web users. (Because apache is a member of ALL -again, web user's- GID.) So, leeps's hint should be one of the important things.



There is nothing close to perfect. What I wrote is just one thing you'll have to keep in mind. So, consider carefully BEFORE you try this solution. (Well, this applies to any other solutions though...)

leeps
10-Mar-2003 03:59


@pollux: additionally, tell your users to set their file-permissions to

- r-- (group) for files

- --x (group) for directories.



this disables the webserver to browse user's directory. if you don't know the filename, you cannot open it, e.g. by running malicious php-code through one of the users scripts.

daniel dot eckl at gmx dot de
08-Aug-2002 02:16


There is a better solution than starting every virtual host in a seperate instance, which is wasting ressources.



You can set open_basedir dynamically for every virtual host you have, so every PHP script on a virtual host is jailed to its document root.



Example:

<VirtualHost www.example.com>

  ServerName www.example.com

  DocumentRoot /www-home/example.com

[...]

  <Location />

    php_admin_value open_basedir     \ "/www-home/example.com/:/usr/lib/php/"

  </Location>

</VirtualHost>



If you set safe_mode on, then the script can only use binaries in given directories (make a special dir only with the binaries your customers may use).



Now no user of a virtual host can read/write/modify the data of another user on your machine.



Windseeker

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Filesystem Security

Cazul 4: parserul PHP in afara directorului radacina web

Last updated: Fri, 01 Aug 2008