cis-ubuntu1604-v200-4-1-14

DevOps & Security

Ensure changes to system administration scope (sudoers) is collected

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CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Control 4.1.14

Profile

Level: 2 - Server
Level: 2 - Workstation
Assessment Status: Automated

Description

Monitor scope changes for system administrations. If the system has been properly configured to force system administrators to log in as themselves first and then use the sudo command to execute privileged commands, it is possible to monitor changes in scope. The file /etc/sudoers will be written to when the file or its attributes have changed. The audit records will be tagged with the identifier "scope."

Note: Reloading the auditd config to set active settings requires the auditd service to be restarted, and may require a system reboot.

Rationale

Changes in the /etc/sudoers file can indicate that an unauthorized change has been made to scope of system administrator activity.

Impact

None.

Audit Procedure

Command Line

Run the following commands:

grep scope /etc/audit/rules.d/*.rules

auditctl -l | grep scope

Verify output of both matches:

-w /etc/sudoers -p wa -k scope
-w /etc/sudoers.d/ -p wa -k scope

Expected Result

Output of both commands should match the rules listed above.

Remediation

Command Line

Edit or create a file in the /etc/audit/rules.d/ directory ending in .rules.

Example: vi /etc/audit/rules.d/50-scope.rules

Add the following lines:

-w /etc/sudoers -p wa -k scope
-w /etc/sudoers.d/ -p wa -k scope

Default Value

By default, no audit rules are configured for sudoers changes.

References

CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Section 4.1.14

CIS Controls

Controls Version	Control
v7	4.8 Log and Alert on Changes to Administrative Group Membership - Configure systems to issue a log entry and alert when an account is added to or removed from any group assigned administrative privileges.