Vulnerability Discussion

It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors.

Failing to disconnect unused protocols can result in a system compromise.

The Stream Control Transmission Protocol (SCTP) is a transport layer protocol, designed to support the idea of message-oriented communication, with several streams of messages within one connection. Disabling SCTP protects the system against exploitation of any flaws in its implementation.

Check

Verify the operating system disables the ability to load the SCTP kernel module.

$ sudo grep -r sctp /etc/modprobe.d/* | grep "/bin/true"

install sctp /bin/true

If the command does not return any output, or the line is commented out, and use of the SCTP is not documented with the Information System Security Officer (ISSO) as an operational requirement, this is a finding.

Verify the operating system disables the ability to use the SCTP.

Check to see if the SCTP is disabled with the following command:

$ sudo grep -r sctp /etc/modprobe.d/* | grep "blacklist"

blacklist sctp

If the command does not return any output or the output is not "blacklist sctp", and use of the SCTP is not documented with the Information System Security Officer (ISSO) as an operational requirement, this is a finding.

Fix

Configure the operating system to disable the ability to use the SCTP kernel module.

Add or update the following lines in the file "/etc/modprobe.d/blacklist.conf":

install sctp /bin/true
blacklist sctp

Reboot the system for the settings to take effect.