Nginx has rapidly grown in popularity and now powers over 30% of all websites – but many admins negligently leave outdated version details exposed. In this comprehensive guide, I‘ll walk through exactly why displaying your Nginx banner diminishes site security, how attackers exploit it, and the step-by-step way you can disable version headers.
By taking this crucial but often overlooked hardening step, you can better obscure your infrastructure to defend against an entire avenue of reconnaissance attacks. Read on to learn why removing the footer from your HTTP responses matters more than ever in today‘s threat landscape.
The Growing Target on Nginx Backs
Over just the past five years, Nginx adoption has nearly doubled – from powering around 15% of websites in 2017 up to over 30% today. It‘s open source codebase, scalability, and approachable configuration format has made it many DevOps teams go-to for both load balancing and directly serving web content.
However, attackers have taken notice. High profile vulnerabilities disclosed in recent years like CVE-2019-9516 and CVE-2013-0337 specifically targeted security flaws in particular Nginx releases. And uptake hasn‘t completely kept pace – nearly 20% of sites still run outdated versions vulnerable to now patched exploits.
By leaving exact version details visible, server admins show their hand to attackers trolling for unpatched targets. Displaying headers like the one below acts like a targeting beacon for zero day exploits:
Server: nginx/1.5.2Here‘s a visual of the attack sequence enabled by exposing version banners:
[diagram of attacker discovering exploit, testing for target version, conducting attack, and accessing underlying server]Luckily obscuring your Nginx footer requires just minutes of effort. Let‘s examine why reducing version intel matters for security, and how you can disable banners using configuration flags.
OWASP Says to Drop Version Breadcrumbs
The technical standards body OWASP sets security best practice guidance followed by developers and ops teams globally.
In their configuration hardening guide, they recommend disabling version headers entirely to:
"Remove any product identifiers, headers or error handling pages that expose product details that are unnecessary.”
This points to how leaving verbose banners in place violates fundamental secure design principles – needlessly spilling details that assist adversarial reconnaissance.
Now that we‘ve covered why exposing implementation isn‘t advisable, let’s shift focus to how to mask server release specifics from responses programmatically.
Restricting Nginx version requires just a one line configuration command – but does need to be added in the right location.
I‘ll cover the steps for common Linux distributions below using standard system paths.
1. Open Your Main Nginx Configuration File
Begin by opening the Nignx config file in your favorite terminal editor – for RPM packages this is usually:
sudo vi /etc/nginx/nginx.confOr for Debian/Ubuntu installs open:
sudo nano /etc/nginx/nginx.confThis houses the main settings parsed globally across all hosted sites.
2. Add the server_tokens Directive
Next, under the main http or server section, add the following line setting server_tokens to off:
http {
server_tokens off;
#...all other http section config
}Or for SSL terminated sites, place it within relevant server blocks instead:
server {
listen 443 ssl;
server_tokens off; # Add this line
#...TLS cert settings
}This directive explicitly disables exposing any verbose version headers for Nginx responses.
3. Save Changes & Restart Nginx
Save your changes and verify syntax validity with:
sudo nginx -tIf all checks out, restart the process:
sudo systemctl restart nginxRefresh site requests will now hide any Nginx version traces.
Going Beyond Just Version Masking
Disabling info leakage from headers joins other security best practices including:
| Hardening Technique | Attacks Prevented |
|---|---|
| Version Hiding | Reconnaissance, Targeting Vulnerable Releases |
| Unused Module Removal | Reduces Attack Surface |
| Jailing / Sandboxing | Stops process-level exploits |
| IP Reputation Filtering | Prevents access from risky networks |
| Web Application Firewall | Blocks OWASP top 10 attacks |
While no single tactic blocks all vectors, each increases adversary effort & limits damage possibilities based on your tech profile.
Confirming Version Header Removal
You can validate your Nginx banner no longer exposes releases using online tools:
$ curl -I https://yourdoma.in
Server: nginxThis now returns a generic server ID without any version detail appended.
Removing your Nginx callsign may seem a small hardening change compared to other efforts. But doing so eliminates an entirely avoidable avenue of network insight for attackers – allowing you to further obscure infrastructure layout as part of a defense-in-depth approach.
Stay Proactive Against Emerging Threat Trends
Although Nginx features a robust codebase, its now widespread footprint makes it an increasing target for cybercriminals. Developments like the growing shift to single page apps, container-centric deployments, and usage as an ingress in cloud native architectures further the reliance on its security.
Staying abreast of new exploit disclosures, promptly patching releases, and hardening configurations aids significantly in thwarting attackers targeting both Nginx itself and applications hosted behind it. Consider regularly checking resources like the Nginx security advisories page for the latest vulnerability notices impacting current or older releases.
Disabling verbose version output removes one quick reconnaissance check adversaries employ when trolling for unpatched servers. Combine it with safe updating habits, unused component removal, and request filtering to incrementally improve resilience against Nginx security incidents.
For further learning on tightening up your instance‘s robustness, check out the Nginx admin certification course over at the Linux Academy. It dives deep into global configuration fine-tuning for both performance and denial of service protections across 60+ in-depth video lessons.
I hope this guide gave you the essentials to knock out this oft-overlooked security improvement quickly! Let me know if you have any other questions on obscuring Nginx presence – I‘m happy to point you towards other best practice hardening steps as well. Stay safe out there!
