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Guides

Practical, sourced walkthroughs of the problems a domain scan most often raises, and what to do about them.

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  • What is a security rating?

    A security rating scores an organisation's cybersecurity from what anyone can observe on the internet. Here is how ratings are built, how the scales differ, and where they stop.

    Security ratings

  • Vendor risk management, step by step

    Your suppliers hold your data, run your services and connect to your systems. Here is a practical way to assess their cybersecurity that does not stop at a questionnaire.

    NIS2, DORA, ISO 27001

  • DORA and ICT third-party risk: what outside-in evidence can show

    DORA makes financial entities fully responsible for the ICT providers they rely on. Outside-in evidence covers a small, concrete part of that duty: what each provider shows the internet.

    (EU) 2022/2554

  • Who does NIS2 cover in Sweden?

    Sweden implements NIS2 through the Cybersecurity Act, Cybersäkerhetslag (2025:1506), in force since 15 January 2026. Here is how to tell whether your organisation is covered, and what follows if it is.

    SFS 2025:1506

  • DKIM, explained

    DKIM puts a signature on every message you send, and a public key in DNS that receivers use to check it. Here is how it works, what a good setup looks like, and how it fits with SPF and DMARC.

    Email security

  • What is an attack surface?

    Your external attack surface is everything an attacker can reach from the internet. Here is what it consists of, why it grows without anyone deciding it should, and how to keep it small.

    Attack surface

  • How to move DMARC from p=none to p=reject

    Take your domain from monitoring to enforcement in stages, without blocking your own mail.

    Email security · 20%

  • The SPF record, explained

    What each part of an SPF record does, how it ends, where the ten-lookup limit bites, and how SPF relates to DMARC.

    Email security · 20%

  • HTTP security headers: what to set, and why

    A handful of response headers and cookie flags close whole classes of attack in the browser. Here is what each one does, a safe value to start from, and which of them TrustSek scores today.

    TLS and web hygiene · 20%

  • A TLS certificate checklist for your website

    Eight things to get right on every HTTPS site, how to check each one yourself, and which of them an outside-in scan reports.

    TLS and web hygiene · 20%

  • Ransomware leak sites: what a claim means, and what to do

    A leak-site claim is a post on a ransomware group's own website naming an organisation it says it has attacked; this guide covers how reliable such claims are, how they are matched to an organisation and the first steps if yours is named.

    Ransomware exposure · 20%

  • NIS2 supplier security: what Article 21 asks, and what outside-in evidence shows

    What the directive actually requires of your supplier relationships, and how a public-evidence scan fits into that work without being mistaken for it.

    NIS2 · Article 21(2)(d)

  • What a cyber insurer can see about your domain

    Before a quote or a renewal, your domain can be assessed from the outside without your involvement, so it pays to see what they will see first.

    All six modules