Linux Security and Hardening

Hardening your systems is a critical aspect of computer security. It’s the process of securing a system by significantly reducing its vulnerability. The more functions a system performs, the larger its attack surface becomes, making it inherently more susceptible to threats. A system focused on a single task is generally more secure than a multi-purpose one.

Effective hardening involves minimizing the available avenues for attackers. Common techniques include:

• Changing default passwords: A fundamental step to prevent unauthorized access.
• Removing unnecessary software: Eliminates potential vulnerabilities associated with unused applications.
• Deleting unused usernames and logins: Reduces the number of potential entry points for attackers.
• Disabling or removing unnecessary services: Minimizes the attack vectors available to malicious actors.

What does hardening actually mean?

In computing, system hardening is the practice of minimizing a system's vulnerability by shrinking its attack surface. This involves reducing the pathways – or attack vectors – that attackers could exploit. Hardening can be achieved through broad security policies like Zero Trust, the Principle of Least Privilege (PoLP), or Defense In Depth. It also manifests in specific, actionable tasks:

• Workforce training: Educating users about security best practices.
• Resource segmentation: Isolating critical systems and data.
• Automated security updates: Ensuring systems are patched against known vulnerabilities.
• Password hashing: Securely storing passwords to prevent compromise.
• Data encryption: Protecting sensitive data both at rest and in transit.
• Ceasing data storage/transmission without encryption: Protecting data confidentiality.

A key element of reducing attack vectors through hardening is identifying and eliminating unnecessary services and processes running on the system. Essentially, the more services a system offers, the wider its attack surface.

In this course, you will gain practical knowledge and skills to harden your Unix and Linux systems, bolstering their defenses against modern cyber threats. Learn how to implement essential hardening techniques and improve your overall system security posture.