Critical HARDN Security Scripts Vulnerabilities: A Deep Dive

Introduction

HARDN is a collection of security hardening scripts designed to enhance system security by enforcing MAC address randomization, TOR routing, directory lockdowns, and kernel security enhancements. However, upon closer examination, these scripts introduce significant vulnerabilities that can be exploited by attackers to compromise system integrity, execute arbitrary commands, and escalate privileges. This article provides an in-depth analysis of the vulnerabilities present in the HARDN scripts, demonstrating how they can be exploited and highlighting the associated risks.

Overview of HARDN security scripts vulnerabilities

While the scripts claim to enhance security, they suffer from severe security flaws, including:

• Unvalidated Command Execution
• Unsafe Use of sudo Without Restrictions
• Tampering with Critical System Files Without Verification
• Overly Permissive File Permissions
• Insecure Use of macchanger
• Lack of Error Handling in Critical Operations
• Failure to Properly Secure TOR Routing
• Potential for System Lockout Due to chattr Misuse

Below, we analyze each of these vulnerabilities in detail, including examples demonstrating how they can be exploited.

1. Unvalidated Command Execution

Vulnerability Description:

The scripts execute system commands without proper validation or sanitization. For example:

subprocess.run(command, shell=True, check=True, text=True)

This usage allows an attacker to inject arbitrary commands by modifying environment variables or manipulating function arguments if they gain access to the script execution.

Exploitation Scenario:

If an attacker can modify the command variable or its parameters, they could execute arbitrary commands, leading to privilege escalation. For instance:

export PATH=/tmp/malicious_bin:$PATH

If a malicious binary replaces sudo, it can capture user credentials or execute arbitrary code.

Mitigation:

• Avoid using shell=True. Instead, use a list format: subprocess.run(['command', 'arg1', 'arg2']).
• Validate inputs to ensure only intended commands can be executed.

2. Unsafe Use of sudo Without Restrictions

Vulnerability Description:

The script executes several sudo commands without checking whether the user has the necessary privileges, potentially allowing attackers to abuse misconfigured sudo rules:

run_command("sudo ip link set eth0 down", "Disabling eth0", test_mode)

Exploitation Scenario:

If an attacker can execute the script with limited privileges but gain access to sudo commands, they could manipulate network configurations, disable security features, or install backdoors.

Mitigation:

• Restrict sudo usage by requiring explicit user confirmation.
• Log all sudo actions and enforce least privilege access control.

3. Tampering with Critical System Files Without Verification

Vulnerability Description:

The script modifies core security files without verifying their integrity, potentially breaking system functionality or allowing attackers to inject malicious configurations:

run_command("echo '* hard core 0' | sudo tee -a /etc/security/limits.conf > /dev/null", "Core dumps disabled", test_mode)

Exploitation Scenario:

An attacker could replace /etc/security/limits.conf with a malicious file that introduces backdoors or weakens system security policies.

Mitigation:

• Perform integrity checks before modifying security-critical files.
• Use atomic file updates to prevent partial modifications.

4. Overly Permissive File Permissions

Vulnerability Description:

The script does not set restrictive permissions for modified security files, allowing unauthorized users to alter them:

shutil.copy(file_path, backup_path)

Exploitation Scenario:

If an attacker gains access to these files, they could alter security settings or disable protections.

Mitigation:

• Enforce strict file permissions (chmod 600) on security-critical configurations.
• Use chattr +i sparingly to prevent accidental lockout.

5. Insecure Use of macchanger

Vulnerability Description:

The script changes the MAC address without verifying the interface’s existence:

run_command("sudo macchanger -r eth0", "Randomizing MAC", test_mode)

Exploitation Scenario:

An attacker could create a rogue interface with the same name, capturing sensitive traffic or causing denial-of-service attacks.

Mitigation:

• Verify interfaces before modifying their settings.
• Ensure only trusted users can modify network configurations.

6. Lack of Error Handling in Critical Operations

Vulnerability Description:

The script assumes all commands execute successfully without checking for failures:

subprocess.run(command, shell=True, check=True, text=True)

Exploitation Scenario:

An attacker could exploit failed commands to leave the system in an inconsistent or vulnerable state.

Mitigation:

• Implement robust error handling and logging.
• Validate command outputs to ensure expected behavior.

7. Failure to Properly Secure TOR Routing

Vulnerability Description:

The script enables TOR without ensuring proper routing rules:

run_command("sudo systemctl enable --now tor", "Enabled TOR service", test_mode)

Exploitation Scenario:

An attacker could intercept or manipulate traffic if TOR is not correctly configured.

Mitigation:

• Implement strict firewall rules to ensure all traffic passes through TOR.
• Verify TOR configuration to prevent leaks.

8. Potential for System Lockout Due to chattr Misuse

Vulnerability Description:

The script makes directories immutable, potentially preventing necessary system changes:

run_command("sudo chattr -R +i /etc", "Made /etc immutable", test_mode)

Exploitation Scenario:

If the script runs on a critical system, administrators may be locked out from making necessary security updates.

Mitigation of the HARDN security scripts vulnerabilities:

• Use chattr sparingly and ensure recovery options are available.
• Provide an automated rollback mechanism.

Conclusion: Proceed with Caution

The HARDN scripts contain severe security vulnerabilities that could be exploited by malicious actors to compromise system integrity, escalate privileges, and disable security protections. While the intention of HARDN is to enhance security, its current implementation does the opposite—introducing critical risks instead of mitigating them.

Recommendations for Users

• Do not run HARDN scripts on production systems without auditing them first.
• Verify each command before execution to avoid unintended consequences.
• Implement strict access controls to prevent unauthorized script execution.
• Consider using well-audited security frameworks instead of custom scripts.

Final Warning

Running these scripts without proper scrutiny could lead to irreversible system damage, privilege escalation, or backdoor installations. Users should exercise extreme caution.

By understanding these vulnerabilities and implementing the recommended mitigations, administrators can protect their systems while ensuring security hardening does not introduce new attack vectors.

• Learn more about Basic Security
• HARDN Project Git Repo