STIGQter: STIG Summary: Canonical Ubuntu 20.04 LTS Security Technical Implementation Guide Version: 1 Release: 1 Benchmark Date: 10 Mar 2021:

The Ubuntu operating system must be configured to use TCP syncookies.

DISA Rule

SV-238333r654174_rule

Vulnerability Number

V-238333

Group Title

SRG-OS-000142-GPOS-00071

Rule Version

UBTU-20-010412

Severity

CAT II

CCI(s)

• CCI-001095 - The information system manages excess capacity, bandwidth, or other redundancy to limit the effects of information flooding types of denial of service attacks.

Weight

10

Fix Recommendation

Configure the Ubuntu operating system to use TCP syncookies by running the following command:

$ sudo sysctl -w net.ipv4.tcp_syncookies=1

If "1" is not the system's default value, add or update the following line in "/etc/sysctl.conf":

net.ipv4.tcp_syncookies = 1

Check Contents

Verify the Ubuntu operating system is configured to use TCP syncookies.

Check the value of TCP syncookies with the following command:

$ sysctl net.ipv4.tcp_syncookies
net.ipv4.tcp_syncookies = 1

If the value is not "1", this is a finding.

Check the saved value of TCP syncookies with the following command:

$ sudo grep -i net.ipv4.tcp_syncookies /etc/sysctl.conf /etc/sysctl.d/* | grep -v '#'

If no output is returned, this is a finding.

Vulnerability Number

V-238333

Documentable

False

Rule Version

UBTU-20-010412

Severity Override Guidance

Verify the Ubuntu operating system is configured to use TCP syncookies.

Check the value of TCP syncookies with the following command:

$ sysctl net.ipv4.tcp_syncookies
net.ipv4.tcp_syncookies = 1

If the value is not "1", this is a finding.

Check the saved value of TCP syncookies with the following command:

$ sudo grep -i net.ipv4.tcp_syncookies /etc/sysctl.conf /etc/sysctl.d/* | grep -v '#'

If no output is returned, this is a finding.

Check Content Reference

M

Target Key

5318

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