0 Linux Account Hygiene - Stopping Insider Threats Before They Start - kevwells.com

Linux Account Hygiene – Stopping Insider Threats Before They Start

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The Problem

Stale accounts are goldmines for attackers. Contractors leave, interns move on, yet their SSH keys and sudo rights linger.

Practical Checklist

  1. Regular Account Review 
    awk -F: '{ print $1 " " $3 }' /etc/passwd | sort -n -k2

    → identify unused accounts.

  2. Disable, Don’t Delete 
    usermod -L accountname

    → preserves forensic history.

  3. SSH Key Hygiene
    Remove stale keys from ~/.ssh/authorized_keys.
  4. Centralised Identity
    Use LDAP/AD or SSSD for joiners/leavers process.

Applied Example

  • A former contractor’s SSH key left active → attacker gained entry months later.
  • Regular review and automation (ansible.builtin.user module) closes this risk.

Why Clients Care

  • Insider threat accounts for 20–30% of breaches.
  • HR compliance requires documented leaver processes.
  • Clean account hygiene reduces audit findings and attack surface.

Security gaps in Linux and cloud systems risk downtime, data compromise, lost business — and compliance failures.

With 20+ years’ experience and active UK Security Check (SC) clearance, I harden Linux and cloud platforms for government, corporate, and academic sectors — ensuring secure, compliant, and resilient infrastructure.

Contact for Contract Assignments

Related posts:

  1. Linux Firewalling – Moving from iptables to nftables
  2. Hardening sudo and PAM – Privilege Control in Linux
  3. VPNs, Bastion Hosts, and Secure Remote Access
  4. Vulnerability Scanning with OpenVAS (Greenbone)