Sentinela.

Blog

Notes from those who keep watch.

Technical writing on external observation, security posture, LGPD and everything that shows up when you look at a domain calmly.

May 22, 2026 · 7 min

CTEM financial risk ALE uptime security

How we compute risk in $/year (ALE) — formula, table and worked example

The A–F grade answers "how is my posture?". ALE answers "how much does this cost per year?". We show the formula, the calibrated table and a worked numeric example — with the inputs you need to fill in to switch it on.

by Carol · read →

May 19, 2026 · 5 min

ASM attack surface CTEM security external exposure

ASM (Attack Surface Management): why you should look at your site like an attacker

ASM is the discipline that maps everything your company exposes to the internet — known or forgotten — and measures the risk before an attacker does. What it is, what it isn't, and where to start.

by Carol · read →

May 12, 2026 · 4 min

pentest audit security compliance ASM

Annual pentest vs continuous auditing: which one protects you more?

A pentest is a snapshot. Continuous auditing is a video feed. Here's when each makes sense, what they cost, and why most companies need both — in different proportions.

by Carol · read →

May 5, 2026 · 4 min

WordPress security ASM vulnerabilities

Secure WordPress in 2026: a checklist of what an attacker sees

Most "secure WordPress" guides end up recommending the same firewall plugin. This one looks at what an attacker actually sees — before they do.

by Carol · read →

April 28, 2026 · 4 min

subdomain takeover DNS ASM security

Subdomain takeover: the forgotten subdomain that becomes a front door

The promo.yourcompany.com you turned off in 2022 still points to Heroku. Today, anyone can grab it back — and run phishing under your domain.

by Carol · read →

April 21, 2026 · 4 min

uptime downtime cost ROI SRE

How much does one hour of downtime really cost (with a calculator)

Downtime isn't just "some lost sales". The real bill includes wasted CAC, SEO penalty, reputation, and support load. Here's how to compute it in dollars.

by Carol · read →

April 14, 2026 · 4 min

SSL TLS certificate security

Expired SSL certificate: what happens and how to avoid it

An expired SSL certificate takes your site down without warning. Why it happens, what the user sees, and why you only find out when someone calls to complain.

by Carol · read →

April 7, 2026 · 3 min

LGPD compliance privacy

Why LGPD is not just a privacy page

Most sites treat LGPD as a footer link. Complying with the law involves a consent banner, a legal basis per purpose, the DPO contact and tracking that respects opt-in.

by Carol · read →

March 31, 2026 · 5 min

malware security WordPress blacklist

How to tell if your site was hacked (and what to do before Google punishes you)

Most hacked sites only find out when Google flags them as unsafe and traffic collapses. The signs show up earlier — if you know where to look.

by Carol · read →

March 24, 2026 · 5 min

email SPF DKIM DMARC deliverability

SPF, DKIM and DMARC: why your emails land in spam

Three acronyms that decide whether your email reaches the inbox or spam. What each one does, how to configure it, and why most companies still get it wrong.

by Carol · read →

March 17, 2026 · 5 min

uptime monitoring comparison

Is free site monitoring worth it? An honest comparison

UptimeRobot, Better Stack, StatusCake, Pingdom — where the free tier is enough and where it costs you more than it saves.

by Carol · read →

March 10, 2026 · 4 min

headers security HTTP

5 HTTP security headers your site probably doesn't have

Security headers are the cheapest and most underused defense on the web. Five you can turn on today without touching application code.

by Carol · read →

March 3, 2026 · 4 min

uptime monitoring SRE

High uptime is not the same as availability

Your monitoring can report 99.99% and your customer can be furious. The difference is in what you monitor, how often, and what you consider "up".

by Carol · read →