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CIS Ubuntu 14.04 LTS - 4.1.6 Ensure events that modify the system's network environment are collected

DevOps & Security
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Collect audit events for changes to network environment files and system calls

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4.1.6 Ensure events that modify the system's network environment are collected (Scored)

Profile Applicability

  • Level 2 - Server
  • Level 2 - Workstation

Description

Record changes to network environment files or system calls. The below parameters monitor the sethostname (set the systems host name) or setdomainname (set the systems domainname) system calls, and write an audit event on system call exit. The other parameters monitor the /etc/issue and /etc/issue.net files (messages displayed pre-login), /etc/hosts (file containing host names and associated IP addresses) and /etc/sysconfig/network (directory containing network interface scripts and configurations) files.

Rationale

Monitoring sethostname and setdomainname will identify potential unauthorized changes to host and domainname of a system. The changing of these names could potentially break security parameters that are set based on those names. The /etc/hosts file is monitored for changes in the file that can indicate an unauthorized intruder is trying to change machine associations with IP addresses and trick users and processes into connecting to unintended machines. Monitoring /etc/issue and /etc/issue.net is important, as intruders could put disinformation into those files and trick users into providing information to the intruder. Monitoring /etc/sysconfig/network is important as it can show if network interfaces or scripts are being modified in a way that can lead to the machine becoming unavailable or compromised. All audit records will be tagged with the identifier "system-locale."

Audit Procedure

On a 32 bit system run the following commands:

grep system-locale /etc/audit/audit.rules
auditctl -l | grep system-locale

Verify output of both matches:

-a always,exit -F arch=b32 -S sethostname -S setdomainname -k system-locale
-w /etc/issue -p wa -k system-locale
-w /etc/issue.net -p wa -k system-locale
-w /etc/hosts -p wa -k system-locale
-w /etc/sysconfig/network -p wa -k system-locale

On a 64 bit system run the following commands:

grep system-locale /etc/audit/audit.rules
auditctl -l | grep system-locale

Verify output of both matches:

-a always,exit -F arch=b64 -S sethostname -S setdomainname -k system-locale
-a always,exit -F arch=b32 -S sethostname -S setdomainname -k system-locale
-w /etc/issue -p wa -k system-locale
-w /etc/issue.net -p wa -k system-locale
-w /etc/hosts -p wa -k system-locale
-w /etc/sysconfig/network -p wa -k system-locale

Expected Result

The audit rules for system-locale should be present and active.

Remediation

For 32 bit systems add the following lines to the /etc/audit/audit.rules file:

-a always,exit -F arch=b32 -S sethostname -S setdomainname -k system-locale
-w /etc/issue -p wa -k system-locale
-w /etc/issue.net -p wa -k system-locale
-w /etc/hosts -p wa -k system-locale
-w /etc/sysconfig/network -p wa -k system-locale

For 64 bit systems add the following lines to the /etc/audit/audit.rules file:

-a always,exit -F arch=b64 -S sethostname -S setdomainname -k system-locale
-a always,exit -F arch=b32 -S sethostname -S setdomainname -k system-locale
-w /etc/issue -p wa -k system-locale
-w /etc/issue.net -p wa -k system-locale
-w /etc/hosts -p wa -k system-locale
-w /etc/sysconfig/network -p wa -k system-locale

Notes: /etc/sysconfig/network is common to Red Hat and SUSE based distributions. You should expand or replace this coverage to any network configuration files on your system such as /etc/network on Debian based distributions.

Reloading the auditd config to set active settings may require a system reboot.

Default Value

Not configured by default.

References

  1. CIS Controls v6.1 - 3.6 Implement Automated Configuration Monitoring System

Profile

  • Level 2 - Server
  • Level 2 - Workstation