cyberstrikeus CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Control 3.3.6
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 commands and verify output matches:
sysctl net.ipv4.icmp_ignore_bogus_error_responses
grep "net.ipv4.icmp_ignore_bogus_error_responses" /etc/sysctl.conf /etc/sysctl.d/*
Expected Result
net.ipv4.icmp_ignore_bogus_error_responses = 1
And the grep command should return:
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
icmp_ignore_bogus_error_responses is enabled (set to 1) by default.
References
- CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0
CIS Controls
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