Disable Kernel Parameter for Accepting ICMP Redirects by Default on IPv4 Interfaces

An XCCDF Rule

Description

To set the runtime status of the net.ipv4.conf.default.accept_redirects kernel parameter, run the following command:

$ sudo sysctl -w net.ipv4.conf.default.accept_redirects=0

To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:

net.ipv4.conf.default.accept_redirects = 0

Rationale

ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages modify the host's route table and are unauthenticated. An illicit ICMP redirect message could result in a man-in-the-middle attack.
This feature of the IPv4 protocol has few legitimate uses. It should be disabled unless absolutely required.

ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_default_accept_redirects
Severity: Medium
References: BP28(R22)

1 11 12 13 14 15 16 18 2 3 4 6 7 8 9

5.10.1.1

APO01.06 APO13.01 BAI04.04 BAI10.01 BAI10.02 BAI10.03 BAI10.05 DSS01.03 DSS01.05 DSS03.01 DSS03.05 DSS05.02 DSS05.04 DSS05.05 DSS05.07 DSS06.02 DSS06.06

3.1.20

CCI-000366 CCI-001551

4.2.3.4 4.3.3.4 4.3.3.5.1 4.3.3.5.2 4.3.3.5.3 4.3.3.5.4 4.3.3.5.5 4.3.3.5.6 4.3.3.5.7 4.3.3.5.8 4.3.3.6.1 4.3.3.6.2 4.3.3.6.3 4.3.3.6.4 4.3.3.6.5 4.3.3.6.6 4.3.3.6.7 4.3.3.6.8 4.3.3.6.9 4.3.3.7.1 4.3.3.7.2 4.3.3.7.3 4.3.3.7.4 4.3.4.3.2 4.3.4.3.3 4.4.3.3

SR 1.1 SR 1.10 SR 1.11 SR 1.12 SR 1.13 SR 1.2 SR 1.3 SR 1.4 SR 1.5 SR 1.6 SR 1.7 SR 1.8 SR 1.9 SR 2.1 SR 2.2 SR 2.3 SR 2.4 SR 2.5 SR 2.6 SR 2.7 SR 3.1 SR 3.5 SR 3.8 SR 4.1 SR 4.3 SR 5.1 SR 5.2 SR 5.3 SR 6.2 SR 7.1 SR 7.2 SR 7.6

A.10.1.1 A.11.1.4 A.11.1.5 A.11.2.1 A.12.1.1 A.12.1.2 A.12.1.3 A.12.5.1 A.12.6.2 A.13.1.1 A.13.1.2 A.13.1.3 A.13.2.1 A.13.2.2 A.13.2.3 A.13.2.4 A.14.1.2 A.14.1.3 A.14.2.2 A.14.2.3 A.14.2.4 A.17.2.1 A.6.1.2 A.7.1.1 A.7.1.2 A.7.3.1 A.8.2.2 A.8.2.3 A.9.1.1 A.9.1.2 A.9.2.3 A.9.4.1 A.9.4.4 A.9.4.5

CM-6(a) CM-7(a) CM-7(b) SC-7(a)

DE.AE-1 DE.CM-1 ID.AM-3 PR.AC-5 PR.DS-4 PR.DS-5 PR.IP-1 PR.PT-3 PR.PT-4

Req-1.4.3

SRG-OS-000480-GPOS-00227

CCE-82470-6

1.4.3
Updated: about 1 year ago

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.default.accept_redirects%3D0%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_default_accept_redirects.conf
        overwrite: true

Disable Kernel Parameter for Accepting ICMP Redirects by Default on IPv4 Interfaces

Description

Rationale

Remediation - Kubernetes Patch