Linux backdoor squirts code into SSH to keep its badness buried

Security researchers have discovered a Linux backdoor that uses a covert communication protocol to disguise its presence on compromised systems.

http://www.theregister.co.uk/2013/11/15/stealthy_linux_backdoor/

 

Should we worry about this?

 

To be clear, this is a backdoor in the sense of an attacker putting a piece of code on the system that makes the system vulnerable, not a backdoor like some part of malicious code built into Linux.

 

A piece of code placed on the server?

 

From the article I assume it's dropped.
I wonder if it's due to mastermind trickery or perhaps just a case of 'sloppy admin'?

 

Did you guys read the comments? They have a lot to say in there, minus the trolls.

 

One of them linked to a Symantec summary and technical details... thanks.

http://www.symantec.com/security_response/writeup.jsp?docid=2013-061917-4900-99&tabid=2

It seems to be client side infection.

 

I wonder how it executes in the first place. Java? Flash? Something more subtle?