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Security report for check24.es

CHECK24 Comparador S.L.U. · Transportation · Spain

Medium risk. 5 critical or high findings in Security headers and SSL/TLS.

Security score

71/100

Risk levelMedium

0–100, higher is better. How it is calculated

CHECK24.es is the Spanish branch of CHECK24, Europe's largest price comparison platform founded in 1999 in Germany. The company offers a wide range of comparison services including car insurance, hotel bookings, car rentals, and other insurance products. It serves millions of customers seeking transparent, objective, and expert-assisted price comparisons to save time and money. The website is professionally designed, mobile-optimized, and integrates advanced tracking and analytics tools while maintaining strong privacy compliance with GDPR. Contact options and customer support are clearly presented, enhancing user trust. The absence of publicly accessible WHOIS data is due to registry restrictions for .es domains and does not detract from the site's legitimacy. Overall, CHECK24.es demonstrates a mature digital presence with robust business and technical infrastructure.

Scanned

NIS2 and GDPR posture

GDPR outside view
83/ 100 · Low
Checks completed
7of 7

NIS2 Art. 21(2)

  1. (a) Risk analysis and security policies: Not visible from outside
  2. (b) Incident handling: One indicator
  3. (c) Business continuity, backups and crisis management: Not visible from outside
  4. (d) Supply chain security: Not visible from outside
  5. (e) Secure acquisition, development and maintenance, including vulnerability handling: Partly checked
  6. (f) Assessing the effectiveness of security measures: Not visible from outside
  7. (g) Cyber hygiene and security training: Not visible from outside
  8. (h) Cryptography and encryption: Partly checked
  9. (i) HR security, access control and asset management: One indicator
  10. (j) Multi-factor authentication and secured communications: Not visible from outside

This scan rated NIS2 with an earlier keyword method that is no longer shown; rescan for the per-article view. Risk management, continuity, supply chain, training, MFA, management oversight (Art. 20) and incident reporting (Art. 23) need internal evidence, and Guard cannot tell whether NIS2 applies to this organisation.

GDPR is indicative only, based on publicly visible signals: Articles 7, 12, 13 and 32 of Regulation (EU) 2016/679 and Article 5(3) of the ePrivacy Directive. Not a certification or legal assessment.

Priority findings

5 findings rated critical or high. Fix these first.

  1. Security headers

    Security headers are instructions your web server sends to every visitor’s browser. Missing ones leave visitors more exposed to attacks such as clickjacking and injected scripts.

    • High

      Missing Strict-Transport-Security header

      Forces HTTPS connections

      What to do: Add "Strict-Transport-Security: max-age=31536000; includeSubDomains; preload"

      • CWE-319
      • OWASP A04:2025
      • ASVS V3.4.1
    • High

      Missing X-Frame-Options header

      Prevents clickjacking attacks

      What to do: Add "X-Frame-Options: DENY" or "X-Frame-Options: SAMEORIGIN"

    • High

      Missing Content-Security-Policy header

      Controls resources the browser is allowed to load

      What to do: Implement a Content-Security-Policy appropriate for your application

      • ASVS V3.4.3
      • OWASP Secure Headers: OWASP Secure Headers Project recommends Content-Security-Policy: default-src 'self'; form-action 'self'; base-uri 'self'; object-src 'none';…

  2. SSL/TLS

    TLS encrypts the connection and proves the site is really yours. Weak or expiring certificates trigger browser warnings and put traffic at risk.

    • High

      Weak Protocols Supported

      Server supports weak protocols: TLSv1.1

      What to do: Disable TLS 1.0, TLS 1.1, and all SSL versions

      • CWE-327
      • OWASP A04:2025
      • ASVS V12.1.1
    • High

      Weak SSL Key Length

      SSL certificate uses 256-bit key, which is considered weak

      What to do: Use at least 2048-bit RSA or 256-bit ECC key

      • CWE-326
      • OWASP A04:2025
      • Mozilla TLS: Mozilla Server Side TLS 6.0 intermediate: rsa_key_size 2048

Need hands-on remediation? Email guard@offseq.com

Keep watching check24.es

This scan found 20 issues across 6 checks. Monitoring re-runs those checks daily, emails you when something material changes and records each fix, so you can show progress.

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Recommended

€25per month

  • TLS certificates and expiry
  • DNS records
  • SPF, DKIM and DMARC
  • Security headers
  • GDPR and NIS2 posture
  • Exposed services
  • Third-party trackers
  • Security score drift

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Prices incl. 21% VAT. Secure checkout by Mollie; sold by SEQ SIA, Latvia.

Results by check

Each check with its score, findings and the evidence it collected.

How this score is calculated

The security score runs 0–100, higher is better. It is the plain average of the security checks that completed in this scan, each counted equally. A check that could not run is left out: it counts neither as a pass nor as a fail.

Counted in this score

SSL/TLS
57
Security headers
15
Email security
87
DNS health
85
Network security
100
GDPR outside view
83
Average
71

Not counted

  • NIS2 outside view: Re-weights evidence from the TLS, email, DNS, network and hygiene checks, so counting it would count that evidence twice. Shown on its own.
  • OffSeq Observations: An AI reading of the site, useful context but not reproducible evidence. Shown on its own.

Findings that cap the score at 49

Each of these is serious on its own, so while any is present the site cannot rate better than high risk, however good the other checks are.

  • The certificate is not trusted by browsers
  • The website is not served over HTTPS
  • A database, remote desktop, file-sharing or Telnet service is reachable from the internet
  • The page loads a script from a compromised source
  • The domain registration has expired
  • SPF authorises every server to send mail as the domain

Partial scans

When the site blocks Guard or most checks cannot run, the score covers only the checks that ran (usually DNS and email), is capped at 75 and is shown as partial, without a risk level.

Risk levels

  • Critical0–25
  • High26–49
  • Medium50–75
  • Low76–100

Technical appendix

Business context, site observations and technical notes gathered during the scan, and the standards behind each reference.

Business context

Business profile

CHECK24 holds a strong market position as a leading price comparison service in Europe, leveraging a commission-based business model. Its competitive advantage lies in offering expert recommendations, transparent pricing, and a broad portfolio of services. The company targets consumers in Spain and Europe who seek efficient ways to compare and purchase insurance, travel, and financial products. The platform's integration of customer reviews and a points program fosters loyalty and engagement. Partnerships with major insurance providers, hotel portals, and car rental companies underpin its extensive offerings. The business shows indicators of scale and maturity, with a large user base and consistent branding across multiple service domains.

Security posture

The website employs HTTPS with strong SSL configuration and implements a comprehensive cookie consent mechanism that respects user privacy and GDPR requirements. Security best practices such as secure login forms, delayed loading of tracking scripts, and absence of exposed sensitive data are observed. However, explicit security headers like Content-Security-Policy and X-Frame-Options are not visibly confirmed and should be audited. There is no public incident response or vulnerability disclosure policy found, which could be improved for transparency. Overall, the security posture is strong with minor areas for enhancement to align with best practices and compliance frameworks.

Recommendations

  1. Conduct a security headers audit and implement missing headers such as Content-Security-Policy and X-Frame-Options.
  2. Publish a clear incident response and vulnerability disclosure policy to improve transparency and trust.
  3. Consider adding a security.txt file at the root domain to facilitate responsible vulnerability reporting.
  4. Regularly review third-party scripts and tracking tools to minimize privacy risks and ensure compliance.
  5. Enhance WHOIS transparency where possible or provide domain registration details on the website for user assurance.
Site observations

Automated reading of the public site. Ratings are indicative.

Business

Company
CHECK24 Comparador S.L.U.
Description
CHECK24 es el comparador de precios más grande de Europa, nacido en Alemania en 1999. Ofrece comparadores para más de 70 categorías de productos y servicios, incluyendo seguros, hoteles, coches de alquiler, tarjetas de crédito, energía y telefonía. Más de 20 millones de clientes usan sus servicios para ahorrar tiempo y dinero con ayuda de expertos.
Key services
Car insurance comparison and contracting, Hotel booking comparison, Car rental comparison, Other insurance comparisons (health, home, life, pet), Customer account with exclusive offers and points program
Content quality
excellent
Branding
consistent

Technology

Stack
JavaScript, Google Tag Manager, Matomo Analytics, CSS3, HTML5
Frameworks
WireframeImporter, WpsetInitializer
Platforms
Desktop web, Mobile web, iOS and Android apps (promoted)
Performance
moderate
Mobile
good
Accessibility
good
SEO
good

Security

Observed score
90/100
Good practices seen
  • HTTPS enforced
  • Cookie consent banner with granular controls
  • No exposed sensitive data in HTML
  • Secure login forms with social login integration
  • Use of Google Tag Manager with delayed loading

Analytics and tracking

Services
Google Analytics, Matomo
Tracking level
moderate
Privacy practices
good

Advertising

Tracking pixels
Google Analytics (via Google Tag Manager), Facebook Pixel (implied by Facebook cookies), Microsoft Advertising
Marketing tools
Facebook, Microsoft, Criteo, LinkedIn
Transparency
good

Site quality

Design
excellent
User experience
excellent
Content relevance
excellent
Navigation
excellent
Professionalism
excellent
Trustworthiness
high

Key observations

  1. Website is fully accessible with rich content and interactive features.
  2. Strong cookie consent mechanism with granular user control.
  3. Multiple service verticals integrated under the CHECK24 brand.
  4. No signs of WAF or content blocking.
  5. WHOIS data unavailable due to registry policy, limiting domain verification.
  6. Use of modern web technologies and analytics tools.
  7. Clear contact phone number and customer support links present.
  8. High-quality customer testimonials and trust signals displayed.
  9. No exposed sensitive data or obvious security issues detected.
Technical notes

Notes

The website uses a modern tech stack including JavaScript frameworks (likely React), Google Tag Manager, and Matomo analytics. It is optimized for desktop and mobile with responsive design and accessibility features. Performance is moderate with room for improvement in loading speed. The site uses custom CSS bundles and deferred JavaScript loading to enhance user experience. There is no detected CMS, suggesting a custom or proprietary platform. Hosting provider details are not disclosed. The technical implementation supports a scalable and user-friendly platform but could benefit from performance tuning and enhanced security header implementation.
Standards and sources

Reference chips under each finding point to the standard, regulation or specification the finding relates to. They are taken from the official datasets below and mapped conservatively: a finding with no defensible link shows none. NIS2 and GDPR references mark where a finding is relevant evidence, not a compliance verdict. Implementing Regulation (EU) 2024/2690 binds digital infrastructure and digital service providers; for other entities it is the most detailed public reading of the Article 21 measures. WCAG, EN 301 549, European Accessibility Act and Web Accessibility Directive references name the requirement an automated accessibility rule relates to; they are not a conformance verdict.

Retrieved 2026-10-25

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