cyberstrikeus 3.3.2 Ensure IPv6 redirects are not accepted (Not Scored)
Profile Applicability
- Level 1 - Server
- Level 1 - Workstation
Description
This setting prevents the system from accepting ICMP redirects. ICMP redirects tell the system about alternate routes for sending traffic.
Rationale
It is recommended that systems not accept ICMP redirects as they could be tricked into routing traffic to compromised machines. Setting hard routes within the system (usually a single default route to a trusted router) protects the system from bad routes.
Audit Procedure
Run the following commands and verify output matches:
sysctl net.ipv6.conf.all.accept_redirects
# Expected: net.ipv6.conf.all.accept_redirect = 0
sysctl net.ipv6.conf.default.accept_redirects
# Expected: net.ipv6.conf.default.accept_redirect = 0
grep "net\.ipv6\.conf\.all\.accept_redirect" /etc/sysctl.conf /etc/sysctl.d/*
# Expected: net.ipv6.conf.all.accept_redirect = 0
grep "net\.ipv6\.conf\.default\.accept_redirect" /etc/sysctl.conf /etc/sysctl.d/*
# Expected: net.ipv6.conf.default.accept_redirect = 0
Expected Result
net.ipv6.conf.all.accept_redirects = 0
net.ipv6.conf.default.accept_redirects = 0
Remediation
Set the following parameters in /etc/sysctl.conf or a /etc/sysctl.d/* file:
net.ipv6.conf.all.accept_redirects = 0
net.ipv6.conf.default.accept_redirects = 0
Run the following commands to set the active kernel parameters:
sysctl -w net.ipv6.conf.all.accept_redirects=0
sysctl -w net.ipv6.conf.default.accept_redirects=0
sysctl -w net.ipv6.route.flush=1
Default Value
Not specified.
References
- CIS Controls: 3 - Secure Configurations for Hardware and Software on Mobile Devices, Laptops, Workstations, and Servers
- CIS Controls: 11 - Secure Configurations for Network Devices such as Firewalls, Routers and switches
Profile
- Level 1 - Server
- Level 1 - Workstation