cyberstrikeus 8.1.6 Record Events That Modify the System's Network Environment (Scored)
Profile Applicability
- Level 2
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 prelogin), /etc/hosts (file containing host names and associated IP addresses) and /etc/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/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
Using Command Line
On a 64 bit system, perform the following command and ensure the output is as shown:
grep system-locale /etc/audit/audit.rules
For 32 bit systems:
grep system-locale /etc/audit/audit.rules
Expected Result
For 64 bit systems:
-a exit,always -F arch=b64 -S sethostname -S setdomainname -k system-locale
-a exit,always -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/network -p wa -k system-locale
For 32 bit systems:
-a exit,always -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/network -p wa -k system-locale
Remediation
Using Command Line
For 64 bit systems, add the following lines to the /etc/audit/audit.rules file:
-a exit,always -F arch=b64 -S sethostname -S setdomainname -k system-locale
-a exit,always -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/network -p wa -k system-locale
# Execute the following command to restart auditd
pkill -P 1-HUP auditd
For 32 bit systems, add the following lines to the /etc/audit/audit.rules file:
-a exit,always -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/network -p wa -k system-locale
# Execute the following command to restart auditd
# pkill -P 1-HUP auditd
Default Value
By default, network environment modification events are not audited.
References
- CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0
Profile
Level 2 - Scored