Waraxe Forums - phpbb 2.0.21: A PoC exploit to change Avatar file location

c2java · Regular user

http://www.milw0rm.com/exploits/2348
im asking for a detailed explanation on how to use this thing. im trying to run it with these arguments selecting my own 2.0.21 phpbb forum as the victim:
perl phpbb.pl localhost/forum [actual admin name] [actual admin password] images/avatars/shell.php
it "thinks" for a sec and then just ends without any output and the avatar location doesnt change. what the hell am i doing wrong, how do i do it right and do i really have to put in the forum's admin's name and his password in order to make it work, coz i dont think if ill find the exploit very practical then..

lenny · Valuable expert

I belive that it should be:

c2java · Regular user

nope, i dont know perl but i can still tell that you need 5 arguments (although i dont use the 5th as you might have noticed coz it gives me errors, i'd like some1 to lighten my mind on this one, i use [d<DEBUG>] as the last argument (just like it says in the exploit's code) and it gives me "The system cannot find the file specified.").
but thanks for the reply anyway ^^

gibbocool · Advanced user

Im pretty sure you need to be admin.

c2java · Regular user

could be, but as i said i am entering admin user and pass and it still doesnt work

lenny · Valuable expert

... If you have access to the admin account, why not just change the path manually... and also, what is the aim of this attack if you alrady have control?

c2java · Regular user

im trying the exploit on my own forum before the actual attack

lenny · Valuable expert

Ok, upon closer inspection you were right - both admin username and password need to be supplied. The avatar location isn't supposed to change I believe - I think that it allows the upload of any file type to any directory through the profile page. The exploit simply adds the poison null byte to the end of the avatar path, possibly breaking any validation attempts by phpBB allowing you to upload malicious files.

Admittedly, the exploit is not very well documented, and no white-paper is provided...

c2java · Regular user

thanks alot but i still cant quite grasp how to choose where to upload the file..

lenny · Valuable expert

Ok this is getting a little tedious Razz

I (to be absolutley honest) dont know. I get the idea behind the exploit, but it goes in no detail how to actually comprimise the system. From what I can see, all this does is add %00 to the avatar url - a simple poison null byte. Im pretty sure this can be exploited, but due to the lack of information provided by the exploit author I cannot do any more easily.

Edit: Ok, so I am doing a little more research - Ill post if i find anything.

c2java · Regular user

thanks, i appreciate it alot