cyberstrikeus 3.2.6 Ensure bogus ICMP responses are ignored (Scored)
Profile Applicability
- Level 1 - Server
- Level 1 - Workstation
Description
Setting icmp_ignore_bogus_error_responses to 1 prevents the kernel from logging bogus responses (RFC-1122 non-compliant) from broadcast reframes, keeping file systems from filling up with useless log messages.
Rationale
Some routers (and some attackers) will send responses that violate RFC-1122 and attempt to fill up a log file system with many useless error messages.
Audit Procedure
Run the following commands and verify output matches:
sysctl net.ipv4.icmp_ignore_bogus_error_responses
# Expected: net.ipv4.icmp_ignore_bogus_error_responses = 1
grep "net\.ipv4\.icmp_ignore_bogus_error_responses" /etc/sysctl.conf /etc/sysctl.d/*
# Expected: net.ipv4.icmp_ignore_bogus_error_responses = 1
Expected Result
net.ipv4.icmp_ignore_bogus_error_responses = 1
Remediation
Set the following parameter in /etc/sysctl.conf or a /etc/sysctl.d/* file:
net.ipv4.icmp_ignore_bogus_error_responses = 1
Run the following commands to set the active kernel parameters:
sysctl -w net.ipv4.icmp_ignore_bogus_error_responses=1
sysctl -w net.ipv4.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