Server Hardening: What it is and Why it’s Essential for your Business’s Cybersecurity

To protect servers from potential cyberattacks and vulnerabilities, server hardening is implementing security measures, such as a hardware firewall. The infrastructure team must ensure that these measures are in place to prevent unauthorized access by hackers.

By implementing server hardening best practices, organizations can enhance the security of their web servers and protect against cyberattacks. This includes utilizing hardware firewalls to safeguard data from unauthorized access.

Additionally, organizations can further bolster their server security by investing in new servers with advanced security features.

This includes securing the web server’s operating system (OS), network, database, and configuration settings.

What is Server Hardening?

Server hardening involves various steps to enhance the security levels of a computer system.

These steps include configuring strong passwords, disabling unnecessary services, applying regular software updates, implementing firewall protection, and monitoring server activity.

The security team must prioritize server hardening to ensure the safety of applications and the overall system.

System hardening ensures that all aspects of the server environment, including firewall and security baselines, are effectively hardened through testing and configuration.

Database hardening involves securing databases in a server environment to prevent unauthorized access or data breaches. This includes implementing server management protocols, setting up a firewall to protect against external threats, and ensuring the web server’s security.

Network hardening strengthens security by implementing intrusion detection systems (IDS) and virtual private networks (VPNs) in server management. This helps to enhance the web server’s security and ensure a secure server environment.

RELATED: Network Hardening: Best Practices & Techniques

Implementing server hardening practices is a good starting point for organizations to fortify their servers against potential threats.

This includes configuring the domain and account settings. Organizations can take proactive steps to secure their servers and create a robust and secure infrastructure for their critical data by implementing a system hardening process.

Understanding the Concept of Server Hardening

Server hardening is a crucial aspect of cybersecurity that reduces the attack surface by eliminating unnecessary services and features.

It helps to enhance the account’s security and protect against potential threats. By configuring servers with secure settings, server hardening aims to mitigate risks and protect against cyber attacks on systems.

The ultimate goal is to create a robust defense system that can withstand various security threats through configuration, network, database, and server hardening.

Reducing the Attack Surface

One of the primary objectives of server hardening, especially for servers, is to reduce the attack surface.

This involves the server hardening process, which includes identifying and eliminating any unnecessary services or features that hackers could potentially exploit. It is essential in the configuration, system, and application hardening process.

By implementing system hardening standards and application hardening on their server, organizations can significantly decrease their vulnerability to attacks by limiting the number of accessible entry points.

Configuring Secure Settings

Server hardening goes beyond simply turning off unused services. It also involves configuring servers with secure settings for system hardening to enhance their overall security posture.

This includes implementing strong passwords, enabling firewalls, and regularly updating software and firmware.

These measures help prevent unauthorized access and ensure that servers are protected against known vulnerabilities through system hardening.

Mitigating Risks

Another key aspect of server hardening is risk mitigation. Organizations can proactively protect their servers from attacks by implementing appropriate measures for system hardening.

This may involve conducting regular vulnerability assessments to identify weaknesses in the system or employing intrusion detection systems to detect suspicious activities.

Protecting Against Cyber Attacks

Cyber attacks are becoming increasingly sophisticated, making organizations need to implement robust defense mechanisms.

Server hardening is vital in protecting against these attacks by securing servers at various levels – from physical security measures such as restricted access to data centers to network security protocols like encryption and VPNs.

Creating a Robust Defense System

The ultimate goal of server hardening is to create a robust defense system that can withstand various security threats.

System hardening requires a multi-layered approach that combines different security measures such as access controls, authentication mechanisms, and regular monitoring for anomalies or intrusions.

Linux Server Hardening Checklist

Preparations

Backup and test a restore

When the operating system is hardened, modifications to its configuration occur. While most modifications are simple to reverse, others may have serious consequences.

Changes to the boot loader, for example. If something goes wrong, the system may become unbootable.

The first step is to confirm that your backup solution is functioning properly. Perform a backup and, if feasible, generate a system snapshot. If something goes wrong, you can roll back to a prior setup.

The capacity to recover data is even more vital than the ability to back up data. That is, after all, why you created the backup in the first place. So, before making changes, run a test restore before building a new backup.

Test before you make changes

This checklist is the result of years of experience in Linux security. Nonetheless, each system is unique and serves a certain function.

Testing should be done with great care before making modifications to systems.

This is especially true for improvements made to operational systems. Instead of just copy-pasting configuration fragments, further study topics you don’t completely grasp.

Hardware security

If you want your Linux distribution to be as secure as possible, assess how effectively the hardware is secured.

Most of these settings may be changed in the BIOS, commonly accessed by pressing a key during startup.

• Set a password to secure the BIOS.

• Consider implementing a boot password.

• Unused storage devices should be disabled (e.g., firewire port)

Partitioning structure and encryption

The installation procedure reveals how effectively a system is hardened. The operating system is installed on a local disk at this step.

A good partitioning structure aids in the separation of executable code from data. It safeguards them both by configuring mount parameters and prevents a file system from becoming unexpectedly full.

There is also the option to encrypt all data during this installation stage. This safeguards the disk if the system is stolen.

It is accomplished by specifying a password or passphrase that must be entered during the boot process of the Linux machine.

• Create multiple partitions (/, /tmp, /usr, /var, /var/log).

• Create a password for encryption.

Bootloader

A bootloader is one of the components that is initiated initially during the boot process. On Linux computers, the GRUB loader is typically used.

• Configure the bootloader using a password.

• Check and tighten configuration file permissions.

Minimal installation

Typically, the software for the system is chosen during the installation step. You may choose between roles, groups of packages, and individual packages.

The best solution is to use fewer packages. It accelerates the installation, saves disk space, and eliminates the danger of insecure software packages later.

• Install only what you require.

• Use the ‘ minimal installation’ option wherever possible.

Software

Software and package management

The majority of software packages are a collection of one or more tools. One of these packages may contain a vulnerability sooner or later.

This is a known software flaw that might cause instability or a security breach.

As a result, the system should be ‘patched’ regularly. This includes testing and installing any security upgrades that are announced.

• Lower the amount of packages to reduce the system’s footprint.

• Disable unnecessary services.

• Install security updates on a regular and priority basis.

Authentication

PAM

PAM, which stands for pluggable authentication module, is used by most Linux distributions. Most authentication parameters, such as where to check for the existence of a user or account, may be configured in the framework.

It also provides setup for password strength, two-factor authentication, and even brute-force defense methods.

File permissions

Each file has a unique owner, group, and file permissions set. The Linux kernel utilizes file permissions as a first layer to determine if a user can access a certain file or directory. It also specifies the access provided, such as read-only or full access.

Although there are numerous conceivable combinations, it is not fine-grained. File ACLs can be used to establish more specific types of access.

• Access typical files with 640 and 750 for directories or more stringently.

• chmod 777 should not be used.

Firewall

A firewall is an important protection tool as part of the network setup. It should be set to block all traffic and allow only the incoming and outgoing data streams essential for the machine to function.

In most cases, a web server will allow inbound HTTPS requests to port 443/TCP. A mail server would often block this port and instead accept connections to port 25/TCP.

• By default, all inbound traffic is denied.

• Open services according to port and protocol (typically ICMP, UDP, or TCP).

• When necessary, restrict ICMP while allowing the computer to function normally.

Windows Server Hardening Checklist

You may drastically minimize your risk of expensive breaches and business interruptions from assaults, malware (including ransomware), and other cyber threats by investing a little effort in Windows Server hardening – finding and remediating security flaws that threat actors could exploit.

Further guidance can be obtained from Center for Internet Security (CIS) and the US Department of Defense Security Technical Implementation Guide (STIG).

Configuration Management

Before delving into specific safe configuration advice, it’s useful to consider some wider security best practices for generating, documenting, and managing configurations:

• Keep an inventory record for each server that details its baseline setup and notes any server changes.

• To limit risk, review and minimize the programs loaded on each server.

• Before making any changes to the production environment, thoroughly test and validate any planned server hardware or software changes.

• Conduct a risk assessment regularly. Use the results to improve your risk management strategy and keep a prioritized list of all servers to guarantee that security vulnerabilities are addressed as soon as possible.

• To simplify configuration administration, keep all servers at the same revision level.

Windows Server Preparation

• Block potentially hostile network traffic on new servers until the operating system is properly hardened. Harden new servers in a network that is not publicly accessible.

• Create a strong BIOS/firmware password to protect the server’s settings from unwanted alterations.

• Disable the recovery console’s automatic administrator login.

• Set the boot order of the device to prevent illegal booting from other media.

Windows Server Installation

• Make sure the system does not shut down during the installation.

• Make a system setup depending on the exact role required. You may accomplish this by using the Security Configuration Wizard.

• When you install Windows Server, use WSUS or SCCM to update it with the newest updates promptly. Security updates address known vulnerabilities that attackers might use to hack a system.

• Enable automated patch availability notification and ensure that all relevant patches, hotfixes, and service packs are evaluated, tested, and implemented as soon as possible.

User Account Security Hardening

• On each server, disable and rename the guest account.

• Disable and rename the local Administrator account on any system in a domain that will employ uniquely named domain admin accounts.

• Reduce your access to privileged functions. Pay close attention to the permissions provided to built-in accounts and groups, such as:

• Local System (NT AUTHORITY\System)

• Network Service (NT AUTHORITY\NetworkService)

• Administrators group

• Backup Operators group

• Users Group

• Everyone group

For example, the Everyone group is assigned the ‘Access this machine from the network’ right by default, granting all users unfettered remote access to shared files.

Ensure that the passwords for system and administrator accounts adhere to standard practices for passwords. Check that these privileged account passwords are at least 15 characters long, with letters, numbers, special characters, and invisible (CTRL ) characters mixed throughout. Assure that your strong password policy necessitates password changes every 90 days.

• Configure account lockout Group Policy following best practices for account lockout.

• Allow users to create and log in using Microsoft accounts.

• Permissions for “everyone” should not be granted to anonymous users.

• Allowing anonymous enumeration of SAM accounts and shares is prohibited.

• Turn off the anonymous SID/Name translation.

• Unused user accounts should be disabled or deleted as soon as possible.

Network Security Configuration and Access Management

• Enable the Windows firewall and ensure that the Firewall is enabled for all Domain, Private, and Public firewall profiles. Configure the Firewall’s default behavior for each Profile to block inbound traffic by default.

• When inbound access to a server is essential, limit it to the relevant protocols, ports, and IP addresses.

• Port blocking should be done at the network configuration level. Analyze which network ports must be open and restrict access to all other ports.

• Only Authenticated Users should be able to access any machine on the network.

• Do not give users the right to “act as part of the operating system.”

• Allow visitor accounts to log in as a service, a batch job, locally, or over RDP.

• Set the RDP connection encryption level to high if RDP is utilized.

• Disable the LMhosts lookup.

• Deactivate NetBIOS through TCP/IP.

• NCACN IP TCP should be removed.

• Configure the Microsoft Network Client and the Microsoft Network Server to sign all communications digitally.

• Unencrypted passwords should not be sent to third-party Server Message Block (SMB) servers.

• Allow no one to access any shares anonymously.

• Configure LAN Manager to reject LM and NTLMv1 authentication.

• Allow the Local System to utilize NTLMv2 computer identity authentication.

• Turn off the Local System NULL session fallback.

• Configure the encryption types that can be used for Kerberos authentication.

• LAN Manager hash values should not be saved.

• Remove file and print sharing from the network configuration. File and print sharing may enable anybody to connect to a server and access vital data without a user ID or password.

Registry Security Configuration

Ensure that all administrators properly grasp how the registry works and what each of its keys does.

Many Windows operating system vulnerabilities can be avoided by altering the following keys:

• Protect the register against unauthorized access.

• If remote registry access is not necessary, disable it.

• Set the MaxCachedSockets (REG DWORD) value to 0.

• SmbDeviceEnabled (REG DWORD) should be set to 0.

• AutoShareServer should be set to 0.

• AutoShareWks should be set to 0.

• Delete all NullSessionPipes key values.

• Delete all NullSessionShares key values.

General Security Settings

• Disable unnecessary services in the default installation to lessen the server’s susceptibility.

• Remove any Windows Server roles or features that are no longer required.

• Enable the built-in NTFS or BitLocker Encrypting File System (EFS).

• If the server has a lot of random access memory, disable the Windows swapfile (RAM). This improves performance and security by preventing important data from being written to the hard disk.

• Use AUTORUN instead. Otherwise, untrusted code can be executed without the user’s awareness; for example, attackers might insert a CD into the system, causing their script to execute.

• Before the user signs in, display the following legal notice: “Unauthorized use of this computer and networking resources is banned…”

• Configure an inactivity restriction to terminate idle interactive sessions and require Ctrl+Alt+Del for interactive logins.

• Ascertain that all volumes are utilizing the NTFS file system.

• Set the permissions for local files and folders. By default, Windows does not limit local files or folders; the Everyone group has unlimited access to most of the machine. Remove this group and give access to files and folders using role-based groups that adhere to the concept of least privilege. Every effort should be taken to eliminate the user privileges Guest, Everyone, and ANONYMOUS LOGON.

• Configure the system date/time to synchronize with domain time servers.

• Set a timer to lock the console’s screen if left unattended.

Audit Policy and Advanced Audit Policy Configuration

• Create an audit policy based on best practices for audit policies to determine which events are written to security logs to obtain insight into important activities.

• Set the event log retention mechanism to overwrite as required and reserve up to 4GB of storage.

• Configure security log shipping to your security information and event management (SIEM) solution, if you have one, to better threat detection and response.

Tips for Additional Hardening

The following options can be configured locally using the Windows Local Security Policy editor or the Local Group Policy editor. Alternatively, in a domain context, utilize the Active Directory GPO (Group Policy Object) Management tools on your domain controller to build centralized configuration settings that will be deployed to all member computers.

Strictly apply the concept of least privilege to limit user rights. The User Rights Assignment settings govern permissions and access to privileged functions for individual users and groups. Windows has many built-in user accounts and groups, sometimes known as Special Identities, with associated rights; they include:

• Local System, or NT AUTHORITY\System

• Network Service, or NT AUTHORITY\NetworkService,

• Administrators

• Backup Operators

• Users

• Everyone

Limiting the assignment of built-in groups and accounts to certain user permissions is critical.

On Windows 10, for example, the ‘Access this computer from the network’ setting is set by default to ‘Administrators, Backup Operators, Everyone, Users,’ granting all users unfettered remote access to shared files.

To eliminate this security risk, restrict these permissions to the Administrators and Remote Desktop User groups to improve access control.

• Set up and activate anti-virus software. Configure it to scan all downloads and attachments and to safeguard you in real-time. Set to update every day.

• Set up and activate anti-spyware software. Set it to update every day.

• Install and activate data loss prevention software (DLP).

• To quickly repair vulnerabilities and enhance application security, examine, test, and apply suggested updates and patches for all operating systems and apps.

• Follow best practices for security, database hardening, and application hardening for all your systems.

Importance of Server Hardening and Key Processes

Server hardening plays a crucial role in safeguarding the security and integrity of server data. Various security measures reduce the risk of unauthorized access or server data breaches.

Let’s delve into the key processes involved in server hardening and understand why they are essential.

Regular Vulnerability Scanning

Regular vulnerability scanning is a fundamental step in server hardening. It involves using specialized tools to identify potential weaknesses or vulnerabilities within the server infrastructure. These scans help detect outdated software versions, misconfigurations, or known security flaws that malicious actors could exploit.

• Pros:

• Identifies vulnerabilities before they can be exploited.

• Allows for timely remediation to minimize risks.

Prompt Application of Security Patches

Applying security patches promptly is another critical aspect of server hardening. Software vendors regularly release updates and patches to address newly discovered vulnerabilities. By promptly applying these patches, organizations can ensure that their servers are protected against known threats.

• Pros:

• Closes security loopholes and strengthens defenses.

• Keeps servers up to date with the latest protection mechanisms.

Conducting Penetration Testing

Penetration testing, also known as pen testing, is an invaluable process in server hardening. It involves simulating real-world attacks on a server to identify its vulnerabilities and assess its resilience against potential threats. This proactive approach helps organizations uncover any weaknesses before attackers exploit them.

• Pros:

• Provides insights into potential attack vectors.

• Enables organizations to strengthen their defenses based on identified weaknesses.

Implementation of Encryption Protocols

Proper implementation of encryption protocols ensures that sensitive information remains protected during transmission. Encryption converts data into an unreadable format, making it useless for unauthorized individuals even if intercepted. Secure Socket Layer (SSL) certificates and Transport Layer Security (TLS) protocols are commonly used encryption methods.

• Pros:

• Protects sensitive data from interception and unauthorized access.

• Ensures confidentiality and integrity of information.

Regular Backup and Disaster Recovery Planning

Regularly backing up server data is an essential part of server hardening. Recent backups ensure critical data can be restored with minimal disruption in a security breach or system failure. Organizations should have a comprehensive disaster recovery plan to outline the necessary steps for restoring operations after an incident.

• Pros:

• Enables quick recovery and minimizes downtime.

• Safeguards against data loss due to unforeseen events.

Server hardening is a continuous process that requires ongoing monitoring, maintenance, and adaptation to emerging threats. By implementing these key processes, organizations can significantly enhance their server security posture and protect their production servers from potential vulnerabilities.

Enhancing User Account Security

To ensure a robust security posture during the server hardening process, focusing on enhancing user account security is essential. Organizations can significantly reduce the risk of unauthorized access and protect sensitive information by implementing various security measures and following best practices.

Enforcing Strong Password Policies

One of the fundamental steps in enhancing user account security is enforcing strong password policies. This involves setting requirements for password complexity, such as using a combination of uppercase and lowercase letters, numbers, and special characters. By doing so, organizations can prevent attackers from easily guessing or cracking passwords.

Pros:

• Strong passwords are harder to crack through brute-force attacks.

• They provide an additional layer of protection for user accounts.

Cons:

• Users may find it challenging to remember complex passwords.

• It can lead to an increase in password reset requests.

Implementing Two-Factor Authentication

Another effective way to enhance user account security is by implementing two-factor authentication (2FA). This adds an extra layer of protection by requiring users to provide two forms of identification: something they know (e.g., a password) and something they have (e.g., a unique code sent to their mobile device).

Pros:

• 2FA provides an additional barrier against unauthorized access.

• Even if a password is compromised, the attacker still needs the second factor to gain access.

Cons:

• Users may find the extra step cumbersome or time-consuming.

• Some legacy systems may not support 2FA implementation.

Regularly Reviewing and Removing Unnecessary User Accounts

Regularly reviewing and removing unnecessary user accounts is crucial for maintaining a secure environment. Unused or inactive accounts pose a significant risk as attackers can exploit them. By conducting periodic audits and promptly deactivating or deleting unused accounts, organizations can minimize the potential for unauthorized access.

Pros:

• Reduces the attack surface by eliminating unused accounts.

• Minimizes the risk of unauthorized access through compromised or forgotten accounts.

Cons:

• It requires ongoing monitoring and management of user accounts.

• Mistakenly removing active accounts can disrupt business operations.

By focusing on these security measures, organizations can enhance the overall security levels during the server hardening. However, it is important to note that these measures are part of a comprehensive security policy. Organizations should also consider implementing other security baselines and best practices recommended by their security teams.

Patching Vulnerabilities and Applying Updates

Regularly applying security patches and updates is a crucial aspect of server hardening. By promptly addressing vulnerabilities in server software, you can significantly reduce the risk of cyberattacks and unauthorized access. Here are some key points to consider when it comes to patching vulnerabilities and applying updates during the server hardening process:

Prompt application of security patches and updates

Installing security patches and updates is essential to protect your server against potential threats. These patches often contain fixes for known vulnerabilities in software applications, operating systems, service packs, and other components. By staying up-to-date with these patches, you can ensure that any weaknesses in your system are addressed promptly.

Regular vulnerability scanning

Conducting regular vulnerability scans helps identify potential weaknesses that need patching during the server hardening process. These scans involve automated tools that examine your system for known vulnerabilities or misconfigurations. By proactively identifying these issues, you can take appropriate measures to mitigate risks before hackers exploit them.

Automated patch management systems

Automated patch management systems can streamline keeping your servers updated with the latest security fixes. These systems automate the deployment of patches across multiple servers, saving time and effort. They also provide monitoring capabilities to track the status of applied patches and identify any failed installations or missing updates.

Best practices for patch management

Implementing best practices for patch management ensures that your server remains secure over time. Some recommended techniques include:

• Establishing a regular schedule for applying patches and updates.

• Testing patches on non-production environments before deploying them in production.

• Prioritizing critical security updates based on severity levels.

• Keeping track of vendor announcements regarding new vulnerabilities or patches.

• Maintaining backups before applying major updates or changes.

• Utilizing antivirus software to detect malware or malicious activities.

Following these best practices can minimize disruptions while effectively protecting your server from potential threats.

Patching in different operating systems

The process of patching vulnerabilities may vary depending on your operating system. For example:

• Linux systems often rely on package managers like apt or yum to install updates.

• Windows servers typically use Windows Update or WSUS (Windows Server Update Services) for patch management.

Familiarizing yourself with the specific procedures and tools relevant to your server’s operating system is essential.

Patching vulnerabilities and applying updates play a vital role in server hardening. By promptly addressing security flaws, conducting regular vulnerability scans, utilizing automated patch management systems, and following best practices, you can significantly enhance the security posture of your server.

Common Tools and Techniques for Server Hardening

There are a variety of tools and techniques that businesses can use to harden their servers and improve their overall security.

These tools and techniques can help businesses harden their servers and improve their overall security. By implementing a combination of these measures and regularly reviewing and updating security policies, businesses can better protect their sensitive information and reduce the risk of a successful cyber attack.

Here are some of the most common ones:

Configuration Management Tools

Configuration management tools like Ansible, Chef, and Puppet can help businesses automate the process of server hardening.

These tools enable businesses to create standard configurations for their servers, which can then be applied automatically to new servers as they are deployed.

Vulnerability Scanning Tools

Vulnerability scanning tools like Nessus and OpenVAS can scan servers for known vulnerabilities and security issues.

These tools can provide businesses with a comprehensive report of their server’s security status and suggest fixes for any identified vulnerabilities.

Intrusion Detection and Prevention Systems

Intrusion detection and prevention systems like Snort and Suricata can help businesses detect and prevent cyber attacks.

These systems use a combination of signature-based and behavioral-based analysis to identify and respond to potential security threats.

Endpoint Protection Tools

Endpoint protection tools like antivirus and anti-malware software can help protect servers from malware and other malicious software. These tools can scan files and monitor network traffic to identify and respond to potential threats.

Encryption Tools

Encryption tools like OpenSSL and BitLocker can help businesses protect sensitive data from being accessed or intercepted by unauthorized parties.

These tools can encrypt data both at rest and in transit, ensuring that it remains secure even if it falls into the wrong hands.

Access Control Tools

Access control tools like Active Directory and LDAP can help businesses control who has access to their servers and what they can do.

These tools enable businesses to enforce strong password policies, implement multi-factor authentication, and restrict access to specific users or groups.

Network Security Tools

Network security tools like firewalls, intrusion prevention systems, and virtual private networks (VPNs) can help businesses secure their network and prevent unauthorized access to their servers.

These tools can control incoming and outgoing network traffic and limit access to sensitive information.

Server Hardening FAQs

What is server hardening?

Server hardening refers to the process of securing a server by implementing various security measures to minimize vulnerabilities and protect against potential cyber threats.

It involves removing unnecessary services, configuring firewalls, establishing strong access controls, regularly patching vulnerabilities, applying updates, enhancing user account security, and more.

Why is server hardening important?

Server hardening is crucial because it strengthens the defenses against potential attacks on an organization’s network infrastructure.

Organizations can reduce vulnerabilities and minimize the risk of unauthorized access or data breaches by implementing robust security measures. Server hardening ensures that sensitive data remains secure and safeguards business continuity.

How do patching vulnerabilities contribute to server hardening?

Patching vulnerabilities involves applying updates released by software vendors to address known weaknesses or bugs in a system.

Organizations can close potential entry points for attackers by regularly patching server vulnerabilities. This helps maintain a secure environment by minimizing the risk of exploitation through known vulnerabilities.

What are some key steps involved in server hardening?

Some key steps involved in server hardening include removing unnecessary services, configuring firewalls, implementing strong access controls, regularly patching vulnerabilities and applying updates, enhancing user account security through strong passwords and multi-factor authentication, and conducting regular security audits.

How can organizations ensure effective server hardening?

Organizations can ensure effective server hardening by following best practices and establishing a comprehensive security checklist.

This includes staying current with the latest security patches, regularly monitoring and auditing systems for vulnerabilities, enforcing strong password policies, implementing multi-factor authentication, and educating employees about cybersecurity best practices.