And that may be the best you'll be able to do in this situation. It's not always possible to compromise a system or escalate privileges.

A couple points to keep in mind:

• If a service has a vulnerability that can only be exploited from an authenticated session, obtaining credentials may help you exploit the service. Otherwise, you'll just have standard access to the service.
• Obtaining access to information is often sufficient. If a service you compromise contains sensitive information, that in itself is enough to sound the alarms. You don't need to root the box on top of that.
• You may be able to leverage that access in other attacks. For example, you may be able to upload a file that could be accessed by a web server. Don't assume each service on a system exists in isolation.

the server is ubuntu i think ok im going to find some vuln but i dont think so its not possible

I have ubuntu, backtrack, fedora, and kubuntu and i can work with all of the so i think i know what is linux! and the difference is so much but not in this case coz i know 100% that the server is ubuntu coz as i mentioned im helping 1 of my friends and he told me before the pentest but im sure i cant find any useable exploit

Man ubuntu isn't a prison is an os like what u've said. But windows is a world and world is prison so windows is going to be a prison for us coz we can't move on from it to ubuntu!!! LoL COZ our habits! And seriously this world (not windows! Real world!) is sick and is a prison too. So save ur mind and make it free good luck

The matrix just said the truth

who thinks the matrix movie was not real?

Thanks u very much , this article can help me .