cyberstrikeus CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0 - Control 3.2.4
Description
The Stream Control Transmission Protocol (SCTP) is a transport layer protocol used to support message oriented communication, with several streams of messages in one connection. It serves a similar function as TCP and UDP, incorporating features of both. It is message-oriented like UDP and ensures reliable in-sequence transport of messages with congestion control like TCP.
Rationale
If the protocol is not being used, it is recommended that the kernel module drivers not be installed to reduce the potential attack surface.
Impact
None.
Audit Procedure
Command Line
Run the following script to verify the sctp module is not available:
#!/usr/bin/bash
{
l_mname="sctp"
l_mtype="net"
l_output="" l_output2=""
l_loadable="$(modprobe -n -v "$l_mname")"
[ "$(wc -l <<< "$l_loadable")" -gt "1" ] && l_loadable="$(grep -P -- "(^\h*install|\b$l_mname)\b" <<< "$l_loadable")"
if grep -Pq -- '^\h*install \/bin\/(true|false)' <<< "$l_loadable"; then
l_output="$l_output\n - module: \"$l_mname\" is not loadable: \"$l_loadable\""
else
l_output2="$l_output2\n - module: \"$l_mname\" is loadable: \"$l_loadable\""
fi
if ! lsmod | grep "$l_mname" > /dev/null 2>&1; then
l_output="$l_output\n - module: \"$l_mname\" is not loaded"
else
l_output2="$l_output2\n - module: \"$l_mname\" is loaded"
fi
if modprobe --showconfig | grep -Pq -- "^\h*blacklist\h+$l_mname\b"; then
l_output="$l_output\n - module: \"$l_mname\" is deny listed in: \"$(grep -Pl -- "^\h*blacklist\h+$l_mname\b" /etc/modprobe.d/*)\""
else
l_output2="$l_output2\n - module: \"$l_mname\" is not deny listed"
fi
if [ -z "$l_output2" ]; then
echo -e "\n- Audit Result:\n ** PASS **\n$l_output\n"
else
echo -e "\n- Audit Result:\n ** FAIL **\n - Reason(s) for audit failure:\n$l_output2\n"
[ -n "$l_output" ] && echo -e "\n- Correctly set:\n$l_output\n"
fi
}
Expected Result
- Audit Result:
** PASS **
- module: "sctp" is not loadable: "install /bin/true"
- module: "sctp" is not loaded
- module: "sctp" is deny listed in: "/etc/modprobe.d/<filename>.conf"
Remediation
Command Line
Run the following script to disable the sctp module:
#!/usr/bin/bash
{
l_mname="sctp"
if ! modprobe -n -v "$l_mname" | grep -P -- '^\h*install \/bin\/(true|false)'; then
echo -e " - setting module: \"$l_mname\" to be not loadable"
echo -e "install $l_mname /bin/false" >> /etc/modprobe.d/"$l_mname".conf
fi
if lsmod | grep "$l_mname" > /dev/null 2>&1; then
echo -e " - unloading module \"$l_mname\""
modprobe -r "$l_mname"
fi
if ! modprobe --showconfig | grep -Pq -- "^\h*blacklist\h+$l_mname\b"; then
echo -e " - deny listing \"$l_mname\""
echo -e "blacklist $l_mname" >> /etc/modprobe.d/"$l_mname".conf
fi
}
Default Value
sctp module is available by default.
References
- NIST SP 800-53 Rev. 5: CM-7
- CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0
CIS Controls
Version 8
4.8 Uninstall or Disable Unnecessary Services on Enterprise Assets and Software - Uninstall or disable unnecessary services on enterprise assets and software.
Version 7
9.2 Ensure Only Approved Ports, Protocols and Services Are Running - Ensure that only network ports, protocols, and services listening on a system with validated business needs, are running on each system.
Profile Applicability
- Level 2 - Server
- Level 2 - Workstation
Assessment Status
Automated