Showing posts from August, 2017

LFI to DB and backdoor

I am decribing a high level, theortical way of converting LFI to DB compromise and creating a backdoor. A long time ago, came across an application which was vulnerable to LFI (Local File Inclusion).
The LFI found was different from traditional one, since the filenmames were not being passed in any parameter, so was hard to detect also. A file called default.cgi contained code that which looks for a file in the directory and include it for some sort of processing, that was a business requirement, if not found, displayed 'File not found' error. So in order to exploit it one need to append a file name just after default.cgi?.  This way, could view any file from app server to OS level. Many sensitive files are easily accessible even from other folders too. /etc/passwd was accessible but /etc/shadow was not present, unfortunately. 
After browsing through almost all the files present at the server, came across a few interesting files (conn.cgi) which contained the logic of connect…