need to know different methods to upload web shell like c99

[HACK-IT]

Hi, ALL

i want to know how i could upload web shells like c99 or r57 to a web and if there are more than way plz tell me step by step

[fancy]

Ay ay ay......why would you want to do that????
I cannot find a legal reason in this action..........

[HACK-IT]

i found a web shell on web server i pen-test it but i could not realize how the attacker has upload this shell specially that even with administrator there is a restriction on uploading things ( it must be .jpg or pdf, or png) so how the attacker runs this php shell so i have taken an image from the system to analyze and i decided to rebuild the same enviro to try act as the attacker and know what are the steps he has taken to by pass extension limitation

[fancy]

Obviously he used a flaw in the php application, e.g. a file upload vulnerability e.g. LFI.

[HACK-IT]

you were right . Thank you Fancy