Record Events that Modify the System's Network Environment

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Description

If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following lines to a file with suffix .rules in the directory /etc/audit/rules.d, setting ARCH to either b32 or b64 as appropriate for your system:

-a always,exit -F arch=ARCH -S sethostname,setdomainname -F key=audit_rules_networkconfig_modification
-w /etc/issue -p wa -k audit_rules_networkconfig_modification
-w /etc/issue.net -p wa -k audit_rules_networkconfig_modification
-w /etc/hosts -p wa -k audit_rules_networkconfig_modification
-w /etc/sysconfig/network -p wa -k audit_rules_networkconfig_modification

If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file, setting ARCH to either b32 or b64 as appropriate for your system:

-a always,exit -F arch=ARCH -S sethostname,setdomainname -F key=audit_rules_networkconfig_modification
-w /etc/issue -p wa -k audit_rules_networkconfig_modification
-w /etc/issue.net -p wa -k audit_rules_networkconfig_modification
-w /etc/hosts -p wa -k audit_rules_networkconfig_modification
-w /etc/sysconfig/network -p wa -k audit_rules_networkconfig_modification

Rationale

The network environment should not be modified by anything other than administrator action. Any change to network parameters should be audited.

Remediation

Shell script

The following script can be run on the host to remediate the issue.

#!/bin/bash

# First perform the remediation of the syscall rule
# Retrieve hardware architecture of the underlying system
[ $(getconf LONG_BIT) = "32" ] && RULE_ARCHS=("b32") || RULE_ARCHS=("b32" "b64")

for ARCH in "${RULE_ARCHS[@]}"
do
	PATTERN="-a always,exit -F arch=$ARCH -S .* -k *"
	# Use escaped BRE regex to specify rule group
	GROUP="set\(host\|domain\)name"
	FULL_RULE="-a always,exit -F arch=$ARCH -S sethostname -S setdomainname -k audit_rules_networkconfig_modification"
	# Perform the remediation for both possible tools: 'auditctl' and 'augenrules'
<ns10:sub idref="xccdf_org.ssgproject.content_value_function_fix_audit_syscall_rule" use="legacy"/>
	fix_audit_syscall_rule "auditctl" "$PATTERN" "$GROUP" "$ARCH" "$FULL_RULE"
	fix_audit_syscall_rule "augenrules" "$PATTERN" "$GROUP" "$ARCH" "$FULL_RULE"
done

# Then perform the remediations for the watch rules
# Perform the remediation for both possible tools: 'auditctl' and 'augenrules'
<ns10:sub idref="xccdf_org.ssgproject.content_value_function_fix_audit_watch_rule" use="legacy"/>
fix_audit_watch_rule "auditctl" "/etc/issue" "wa" "audit_rules_networkconfig_modification"
fix_audit_watch_rule "augenrules" "/etc/issue" "wa" "audit_rules_networkconfig_modification"
<ns10:sub idref="xccdf_org.ssgproject.content_value_function_fix_audit_watch_rule" use="legacy"/>
fix_audit_watch_rule "auditctl" "/etc/issue.net" "wa" "audit_rules_networkconfig_modification"
fix_audit_watch_rule "augenrules" "/etc/issue.net" "wa" "audit_rules_networkconfig_modification"
<ns10:sub idref="xccdf_org.ssgproject.content_value_function_fix_audit_watch_rule" use="legacy"/>
fix_audit_watch_rule "auditctl" "/etc/hosts" "wa" "audit_rules_networkconfig_modification"
fix_audit_watch_rule "augenrules" "/etc/hosts" "wa" "audit_rules_networkconfig_modification"
<ns10:sub idref="xccdf_org.ssgproject.content_value_function_fix_audit_watch_rule" use="legacy"/>
fix_audit_watch_rule "auditctl" "/etc/sysconfig/network" "wa" "audit_rules_networkconfig_modification"
fix_audit_watch_rule "augenrules" "/etc/sysconfig/network" "wa" "audit_rules_networkconfig_modification"