As system administrators, we often need to search for potential backdoors or shells in web sites for servers we manage. Its not something we want to happen, but need to do especially if we are supporting legacy code; have gotten behind on patches or updates; or a new exploit slipped through the cracks due to its popularity and how quickly it spread.
I wrote a quick bash script based on a php version I found here.
Here is the short script:
A lot of recent talks about “securing the cloud” but let me give you my take on it.
I am in the cloud, businesses are in the cloud, but which cloud? Is any one cloud environment more secure than the other? Let me give you a few things I have learned about the cloud….cause this might seem rather alarming to some or most.
Treat all cloud environments as a hostile environment. Treat it like a wide open door to your business infrastructure, matter of fact, treat it like something blew 2 of the 4 outer parameter walls off of your business along with half of the roof coming down. Rethink what you consider secure, how you secure services and applications, and treat it like you just handed everything to a blackhat hacker.
Almost every cloud environment I have used or tested offers a “private ip address” but is it really private? If you dig around, you will find that it is not. Matter of fact, it seems that others with those private ip addresses believe they have their own vlan switch of private ip address ranges segregated from everyone else….but fact is, you share your data on your private ip address range with many other clients on the same private ip address range. Why? Because you are all sharing a cut of the cpu, memory, network cards, etc of the same physical server. Even though you might secure your forward facing applications, you would be surprised how many applications within the private ip addresses are not secured. Why? Because people automatically think of it in terms of “our local network or private lan”. Why? Because its in the same ip range as a private network.
See EXAMPLE 1 below
And because people treat it like a private lan network, they do the craziest things like “unpatched apache or other insecure software”, how about mysql root without a password on the private lan for ease of administration, or what about using the private lan to send critical confidential customer (or patient) records across to another failover server on the private lan….unencrypted. You see where this is going??
See EXAMPLE 2 below
And then lets talk about pre-made cloud environments…..
So, sometimes I write scripts to be a quick way to monitor or audit other systems. The following script was written as a way to quickly audit a list of domain names, i.e. from a list of 1 domain per line. Initially it was used to audit a list of subdomains from a nettica account to see if the name still resolved and if so, determine if the server was running ssh with a valid key. I have realized the script has a lot of uses, as a way to validate hosts are up and also validate ssh is running. You could also replace the “ls” command in order to monitor other services on a server or even top or similar. So, this script could start as a foundation and easily expanded upon.
First, you need a text file containing 1 domain name per line, like this:
domain1.com
domain2.com
domain3.com
sub.domain4.com