Securing Critical Internet-Facing Infrastructure After a Cyber Incident

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Andy Jenkinson raises a critical question: “How many weeks does it take to secure critical Internet-facing and connected infrastructure, including websites, following a major Cyber incident?” The reality is that many organizations struggle with prolonged recovery times, leaving them vulnerable to further attacks.

You Should Know:

1. Immediate Post-Incident Actions

  • Isolate Affected Systems: 
    sudo iptables -A INPUT -s <malicious_IP> -j DROP 
sudo firewall-cmd --add-rich-rule='rule family="ipv4" source address="<malicious_IP>" reject' --permanent
  • Preserve Logs for Forensics: 
    journalctl -u sshd --no-pager > /var/log/sshd_incident.log

2. Vulnerability Assessment & Patch Management

  • Scan for Vulnerabilities: 
    nmap -sV --script vuln <target_IP>
  • Apply Critical Patches (Linux): 
    sudo apt update && sudo apt upgrade -y
  • Windows Patch Management: 
    wuauclt /detectnow /updatenow

3. DNS & Web Infrastructure Hardening

  • Check DNS Misconfigurations: 
    dig +short MX example.com 
nslookup -type=any example.com
  • Enable DNSSEC: 
    sudo named-checkconf /etc/bind/named.conf.options 
sudo systemctl restart bind9

4. Continuous Monitoring & Threat Intelligence

  • SIEM Log Aggregation (ELK Stack): 
    sudo systemctl start elasticsearch 
sudo systemctl start kibana
  • Automated Threat Feeds: 
    curl -s https://feodotracker.abuse.ch/downloads/ipblocklist.txt | sudo tee -a /etc/ufw/blocklist.txt

5. Incident Response Playbook

  • Containment Script (Example): 
    !/bin/bash 
MAL_IP=$(grep "Failed password" /var/log/auth.log | awk '{print $11}' | sort -u) 
for ip in $MAL_IP; do 
ufw deny from $ip 
done

What Undercode Say:

Securing critical infrastructure post-incident requires automation, rapid patching, and threat intelligence integration. Organizations must adopt proactive measures like Zero Trust Architecture (ZTA) and automated incident response workflows to reduce recovery time.

Expected Output:

  • Linux: Blocked malicious IPs via iptables/ufw.
  • Windows: Forced updates via wuauclt.
  • DNS: Validated DNSSEC deployment.
  • Threat Intel: Updated blocklists via automated `curl` scripts.

Prediction:

With rising DNS-based attacks, organizations will increasingly adopt AI-driven anomaly detection to preemptively secure internet-facing assets.

(Relevant DNS Security Best Practices)

IT/Security Reporter URL:

Reported By: Andy Jenkinson – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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