Jamie Scaife - United Kingdom 🇬🇧 

Restricting Who Can Issue Certificates for Your Domain with CAA

Thursday 13th February 2020

Certificate Authority Authorisation (CAA) is a security control that can be used to restrict the Certificate Authorities (CAs) that are permitted to issue certificates for your domain. The purpose of this is to help ensure that only explicitly whitelisted CAs are able to issue certificates, and also to report on any attempted violations of this policy.

CAA policies are set using the CAA DNS resource record type, and it has been mandatory for issuing CAs to check for and comply with CAA policies since 8th September 2017. The CAA specification is defined in RFC8659.

The following sample CAA policy marks Let's Encrypt as the only CA authorised to issue certificates for example.com, while requesting that violations are reported to the caa-violations@example.com mailbox:

example.com IN CAA 0 issue "letsencrypt.org"
example.com IN CAA 0 iodef "mailto:caa-violations@example.com"

This policy will then be checked by CAs when a certificate request is submitted for your domain. Continue reading...

Security TLS RFC

Testing Your Ability at Spotting Lookalike Domain Names

Sunday 12th January 2020

I have created a web-based JavaScript app/game which allows you test your ability at spotting potential lookalike or phishing domains in real-time.

A screenshot of the Lookalike Domain Names Test app.

The app displays the domain name of a well-known website, with a random set of permutations applied to it. You must then select whether the domain is 'Real' or a potential 'Lookalike'.

Lookalike domain names are a very effective phishing technique, as they exploit the natural way that the human brain interprets writing. The brain will automatically make assumptions and fill in gaps when reading, allowing users to be easily fooled if a phishing domain looks almost identical to the legitimate domain. Continue reading...

Security Domain Names

Securing Inbound Email Transport with MTA-STS and STARTTLS-Everywhere

Friday 27th December 2019

The web security ecosystem has matured significantly over the past few years, partly thanks to organisations like Let's Encrypt and the ACME protocol, as well as because of encouragement from browser vendors for websites to implement HTTPS and other security controls such as Content Security Policy.

However, the email ecosystem unfortunately hasn't seen such levels of development. Existing technologies for securely transporting emails, such as STARTTLS, are not as resistant to attacks as their web-based counterparts, and the implementation methods available to sysadmins are far more limited.

In this blog post I'm going to talk about three new email security technologies: MTA-STS, TLSRPT and STARTTLS-Everywhere. These allow you to have greater control and insight into how your emails are securely transported. In this post I will focus on security and reporting for inbound/incoming emails, however in the future I may also cover outbound/outgoing emails. Continue reading...

Security TLS RFC

A Look at PureDarwin - an OS based on the open source core of macOS

Wednesday 27th November 2019

PureDarwin is a community project to make Darwin, the open source operating system developed by Apple Inc. that macOS is built upon, more usable by providing bootable ISOs and documentation.

The puredarwin.org homepage, showing the Hexley the Platypus mascot.

The project was founded in 2007, and is seen as the informal successor to the OpenDarwin project (which closed down in 2006). PureDarwin is a downstream project of Darwinbuild, combining the open source Darwin base with other FOSS tools (such as X.org) to produce a usable system. Continue reading...

Apple Virtualisation