Checking out backdoor shells

["Adam Behnke" <adam () infosecinstitute com>]

A backdoor shell can be a PHP, ASP, JSP, etc. piece of code which can be
uploaded on a site to gain or retain access and some privileges on a
website. Once uploaded, it allows the attacker to execute commands through
the shell_exec () function, upload/delete/modify/download files from the web
server, and many more. For defacers, it allows them to navigate easily to
the directory of the public_html or /var/www and modify the index of the
page. 

 

In this write-up, we will be talking about PHP backdoor shells, how they
work, how to detect them and remove them. Below is a simple PHP code that is
very popular and is scattered all over the web
(http://stackoverflow.com/questions/3115559/exploitable-php-functions;
http://shipcodex.blogspot.com/2012/01/simple-php-backdoor-shell.html).  This
code allows an attacker to execute *nix commands. For the full write up at
InfoSec Institute, check here:
http://resources.infosecinstitute.com/checking-out-backdoor-shells/

 

 

 

 

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