The remote host is running an inherently insecure protocol or application.
A shell server was noted on the host. Typically, shells are used by remote users to manage operating systems. Shells that pass traffic in plaintext introduce a risk to confidentiality and privacy. In addition, many shells are used by malicious individuals as part of a Trojan program or remote buffer overflow exploit.
Ensure that the remote shell is secured against data leakage and that it is a valid, approved means of managing the remote machine.