cyberstrikeus CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0 - Control 3.3.3
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.
Impact
None.
Audit Procedure
Command Line
Run the following command to verify bogus ICMP responses are ignored:
sysctl net.ipv4.icmp_ignore_bogus_error_responses
grep -E '^\s*net\.ipv4\.icmp_ignore_bogus_error_responses\s*=\s*1\b' /etc/sysctl.conf /etc/sysctl.d/*.conf
Expected Result
net.ipv4.icmp_ignore_bogus_error_responses = 1
Remediation
Command Line
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
net.ipv4.icmp_ignore_bogus_error_responses = 1
References
- NIST SP 800-53 Rev. 5: CM-7, SC-5
- CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0
CIS Controls
Version 8
4.1 Establish and Maintain a Secure Configuration Process - Establish and maintain a secure configuration process for enterprise assets.
Version 7
5.1 Establish Secure Configurations - Maintain documented, standard security configuration standards for all authorized operating systems and software.
Profile Applicability
- Level 1 - Server
- Level 1 - Workstation
Assessment Status
Automated