Configure sudoers Audit Rules

# SPDX-FileCopyrightText: 2025 Greenbone AG
# Some text descriptions might be excerpted from (a) referenced
# source(s), and are Copyright (C) by the respective right holder(s).
#
# SPDX-License-Identifier: GPL-2.0-only

# ------------------------------------------------------------------
# METADATA
# ------------------------------------------------------------------

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.130282");
  script_version("2025-11-21T05:40:28+0000");
  script_tag(name:"last_modification", value:"2025-11-21 05:40:28 +0000 (Fri, 21 Nov 2025)");
  script_tag(name:"creation_date", value:"2025-05-07 11:44:17 +0000 (Wed, 07 May 2025)");
  script_tag(name:"cvss_base", value:"0.0");
  script_tag(name:"cvss_base_vector", value:"AV:L/AC:H/Au:S/C:N/I:N/A:N");
  script_tag(name:"qod", value:"97");

  script_name("Configure sudoers Audit Rules");

  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2025 Greenbone AG");
  script_family("Policy");
  script_dependencies("compliance_tests.nasl", "compliance_os_check.nasl");

  script_mandatory_keys("Compliance/Launch", "policy/ssh/login/euleros_openeuler");

  script_xref(name:"Policy", value:"EulerOS Baseline: openEuler Security Configuration Baseline (v1.0.0): 4. Log Audit: 4.1 Audit: 4.1.13 Configure sudoers Audit Rules (Recommendation)");
  script_xref(name:"Policy", value:"openEuler Baseline: openEuler Security Configuration Baseline (v1.0.0): 4. Log Audit: 4.1 Audit: 4.1.13 Configure sudoers Audit Rules (Recommendation)");

  script_tag(name:"summary", value:"The sudo command allows common users to perform privileged
operations as the root user, which is highly risky. Though attackers cannot access the root user
easily, they can escalate the privilege using the sudo command. You are advised to configure audit
for the /etc/sudoers file and the /etc/sudoers.d directory by recording audit logs for read and
write operations on them. This allows you to trace modification and read operations on the
configurations (configurations needs to be read for privilege escalation). If audit is not
configured for sudoers, unauthorized privilege escalation cannot be traced.

By default, audit rules for sudoers are not configured in openEuler. You are advised to configure
rules based on the actual service scenario.");

  exit(0);
}

include("ssh_func.inc");
include("host_details.inc");
include("policy_reporting_module.inc");

title = "Configure sudoers Audit Rules";

solution = "Create a rule file, for example, sudoers.rules, in the /etc/audit/rules.d/ directory
and add audit rules to the file.

# vim /etc/audit/rules.d/sudoers.rules
-w /etc/sudoers -p wa -k
-w /etc/sudoers.d -p wa -k

Restart the auditd service for the rules to take effect.

# service auditd restart
Stopping logging: [ OK ]
Redirecting start to /bin/systemctl start auditd.service";

check_type = "SSH_Cmd";

action = 'Run the command in the terminal:
# auditctl -l 2>/dev/null | grep "^-w /etc/sudoers"';

expected_value = 'The output should not be empty';

# ------------------------------------------------------------------
# CONNECTION CHECK
# ------------------------------------------------------------------

if(!get_kb_item("login/SSH/success") || !sock = ssh_login_or_reuse_connection()){

  report_ssh_error(title: title,
                   solution: solution,
                   action: action,
                   expected_value: expected_value,
                   check_type: check_type);
  exit(0);
}

# ------------------------------------------------------------------
# CHECK : Check "sudoers"` in auditctl list
# ------------------------------------------------------------------

step_cmd = 'auditctl -l 2>/dev/null | grep "^-w /etc/sudoers"';
actual_value = ssh_cmd(socket:sock, cmd:step_cmd, return_errors:TRUE, return_linux_errors_only:TRUE);

if(eregmatch(string: actual_value, pattern:"(No such file or directory|Permission denied|Command not found|Segmentation fault|service not found|is not running|syntax error near unexpected token|syntax error: unexpected end of file)", icase: TRUE)){
  compliant = "incomplete";
  comment = "Something went wrong during the audit check. Please try again.";
}else if(actual_value){
  compliant = "yes";
  comment = "Check passed";
}else{
  compliant = "no";
  comment = "Check failed";
}

# ------------------------------------------------------------------
# REPORT
# ------------------------------------------------------------------

target = get_kb_item("policy/ssh/login/os-release");
comment = "Target: " + target + "\n" + comment;

report_audit(action: action,
             actual_value: actual_value,
             expected_value: expected_value,
             is_compliant: compliant,
             solution: solution,
             check_type: check_type,
             title: title,
             comment: comment);

exit(0);