Hello friend, do you operate websites and web apps running on Apache Tomcat? As an experienced cybersecurity professional and Java enthusiast, I‘ve helped many organizations secure their Tomcat deployments. In this comprehensive guide, I‘ll impart that expertise to help you properly harden and enhance the security of Tomcat instances under your responsibility.
By collaborating with your security and operations teams to methodically implement these best practices, you can minimize risk exposure and prevent many common threats targeting Java web apps. So let‘s get started on this journey towards an A+ secured Tomcat!
Modern Web Applications Face Increasing Threats
As digital transformation accelerates across industries, Internet-facing web apps have become crown jewels for businesses. But with valuable data and functionality accessible online, cyberattackers are heavily targeting web technology stacks. Consider these alarming statistics:
- Web apps were involved in over 43% of breaches according to the 2022 Verizon DBIR. SQLi and XSS topped web hacking techniques.
- A 2022 F5 survey found 78% of organizations observed increased web application threats since 2020. 93% expressed concern over web app security risks.
- Cybercriminals are strategic about exploiting trending technologies. With an estimated 70% market share of Java application servers, Tomcat is a prime target.
Unfortunately Java web apps like those running on Tomcat can be riddled with vulnerabilities – the Flexera 2022 report identified it‘s the #3 most vulnerable software component over last 2 years. Unpatched exploits in underlying software are just one threat vector – poor configuration and lack of hardening also enables attacks.
That‘s why a holistic defense-in-depth approach is required to secure Tomcat…which leads us to this guide!
Prerequisites
To get the most value out of this article, I‘ll assume you have:
- Access to administer Tomcat application server (e.g installing software, editing configs)
- Familiarity with core Tomcat architecture and basic system admin commands
- Ability to make changes to Production/Test Tomcat environments safely
- Approvals from InfoSec to implement security hardening controls
If you need help getting approvals or protecting production workloads during changes, partner with your security-minded cohorts!
Now, let‘s jump in to those step-by-step guidelines for fortifying your Tomcat.
Step 1 – Camouflage Tomcat Fingerprint
Like overly trusting individuals, out-of-the-box software installs tend to reveal too much sensitive information! 😨 By voluntarily disclosing version details and configurations, unhardened software enables fingerprinting attacks allowing perpetrators to craft precise exploits.
For example inspecting HTTP response headers from a new Tomcat reveals worrying intelligence:
Server: Apache-Coyote/1.1
X-Powered-By: Servlet/4.0 JSP/2.3Armed with this insight on Tomcat generation and Java components, hackers can reference CVE databases, exploitDB archives and underground forums to obtain and weaponize corresponding attacks.
To eliminate this intel leakage, we‘ll erase any fingerprints that expose Tomcat specifics:
- Edit
$CATALINA_HOME/conf/server.xml - Add
Serverattribute within Connector, leave value blank - Comment out X-Powered-By Filter parameter
- Restart Tomcat and verify headers no longer disclose Tomcat
Per PCI DSS controls, disguising web server identity is a baseline requirement for security due diligence. Are your web apps revealing too much? Use tools like nmap, Nikto, WhatWeb to audit exposures.
Step 2 – Encrypt Communication with SSL/TLS
Without encryption, data transmitted between end users and your web application will be exposed to intermediary threats. The perils of unencrypted web traffic include:
- Hotels/WiFis/ISPs spying on usernames, passwords in clear text
- Attackers intercepting session tokens to steal user identities
- Injection of malicious code or content into page responses
- Violations of compliance mandates around data security (PCI DSS again!)
To secure connections and prevent these risks, we‘ll encrypt the client-server channel using industry-standard SSL/TLS protocols:
- Acquire trusted SSL certificate matching domain
- Convert certificate format into Java keystore
- Configure Connector node within
server.xml - Redirect web app traffic to HTTPS
With HTTPS enforced, your web apps will reassure users with padlocks while keeping their data safe from prying eyes!
PS: For bonus points, enable HSTS to instruct clients to only interact with your web apps using HTTPS going forward.
Step 3 – Lock Down Access with Authentication
Currently any random Internety visitor can freely view pages or invoke functionality on our web application – but this promiscuous visibility warrants restrictions!
To limit access to legitimate users, we will integrate authentication requiring valid credentials:
- For internet-facing sites, integrate Single-Sign On so users validate against enterprise directory.
- For admin interfaces like Manager app, bind authentication to secure LDAP server.
Choosing strong authentication passwords as per modern guidance thwarts multiple common attack categories:
- Brute force credential stuffing is deterred by longer passwords with complexity
- Compromise of individual user accounts only enables access to attacker‘s scope
- Multi-factor authentication requirements makes misuse of stolen passwords useless!
As part of implementing authentication, we should also disable any default admin accounts and ensure access is granted based on necessity.
Step 4: Sever Unnecessary Default Apps
In their infinite wisdom, software vendors bundle freebies and bonus features assuming everyone loves free samples! 🎁
But in reality, most users end up ignoring these loosely integrated extras that unknowingly introduce risks…
In Tomcat‘s case, the following public apps warrant removal considering limited use in enterprise settings:
ROOTweb app only useful in developmentExamplesapp containing sample code with security issues- Verbose Tomcat
Docsrevealing information to attackers Managerapp allowing admin functions without auth
To prune unnecessary attack surface:
- Delete inflating apps from
$CATALINA_HOME/webapps - Restart Tomcat to prevent auto-redeployment
- Confirm only in-use web apps still active
Goodbye digital clutter and unused functionality! 👋
Step 5: Institute Least Privilege
Access controls are pivotal, but we should also consider privilege minimization to limit impact of potential intrusions.
Currently on many Tomcat deployments, the service and web applications run with privileges tied to powerful OS-level users like root or tomcat.
This over-privileged execution is concerning since any unpatched RCE or web shell drops attacker into buckets of permission!
To exercise restraint, we‘ll apply principle of least privilege:
- Create OS-level user like
webappslimited to app folders - Update file permissions for web app resources
- Launch Tomcat process under confined context
Now in case of compromise, the attacker is restricted by bounds we enforce, keeping crucial system files and services out of reach! 💪
Fine-grained segmentation and isolation should be baked into modern architecture – use containers, virtualization and edge security to multiply these controls.
Secure By Default with Policy-Driven Hardening
Beyond reactively applying hardening controls, we should preemptively block attacks by embedding security within foundational configurations.
Tools like Ansible, Chef, Puppet and Docker allow templatizing and enforcing secure baselines across infrastructure:
# Apache Tomcat Hardened Docker Container
FROM tomcat:9-jre11
RUN sed -i ‘s/^SHUTDOWN$/DONOTGUESSME/‘ /usr/local/tomcat/conf/server.xml # Change shutdown command
RUN rm -rf /usr/local/tomcat/webapps/* # Remove unused sample apps
RUN useradd -M -d /usr/local/tomcat webapps # Add least privilege user
USER webapps
EXPOSE 8080
CMD ["catalina.sh", "run"] Now freshly deployed Tomcat instances launch hardened without relying on manual checks!
Policy engines like Kubernetes Gatekeeper also allow mandating configs. For bonus points, integrate security scanners to validate defenses over time!
Expand Monitoring for Ongoing Threat Detection
Through hardening, we‘ve significantly elevated defenses – but resilient security requires persistent visibility across environments.
By ingesting rich telemetry and leveraging analytics, we can catalyze threat hunting to reveal novel attack behaviors:
Audit logs tracking admin actions expose abuse like unusual deployments
IDS signatures tuned for Java app attacks identify known exploit attempts
File integrity monitoring alerts on unauthorized config changes
Vulnerability management regularly tests defenses against new weaknesses
Proactively instrument alerting rules focused on breaching tactics! Critically analyzing event data helps connecting dots between innocuous activities to reveal sophisticated multiparty attacks.
For determining residual risk, conduct application penetration tests after hardening to validate effectiveness!
Conclusion
And there you have it my friend – a robust application security program tailored to safeguard entrusted Tomcat instances! Let‘s quickly recap key guidelines:
- Conceal identities via header modification
- Enable encryption to protect communications
- Authenticate users and disable default access
- Prune unnecessary apps minimizing code
- Configure least privilege across all layers
- Standardize hardening as code/policy
- Continuously monitor attack lifecycles
I hope walking through these best practices gives you confidence to secure critical workloads. Though this covers major steps for hardening Tomcat specifically, web application security is an evolving landscape requiring perpetual partnership between application teams and cyberdefenders.
Reach out if any part of this guide needs clarification or if you have suggestions for further strengthening defenses! Stay safe out there and happy Tomcatting! 😸
