"The most dangerous apps aren't the ones you download. They're the ones you forgot about."

The family tablet had been getting worse for weeks.

Not "a bit slow" worse. Painful. Every tap took seconds to register. Scrolling stuttered like a slideshow. Apps crashed mid-use. And the ads - they were relentless. Full-screen popups appearing out of nowhere, covering whatever you were doing, sometimes impossible to close without accidentally tapping through to whatever rubbish they were pushing.

At first I assumed it was just age. The tablet wasn't new. Maybe it needed a restart, maybe an update, maybe it was just time to replace it. But something didn't sit right. It had been fine a few months ago. This felt sudden. This felt like something had changed.

So I started digging. Opened Settings, went to the app list, sorted by battery usage and data consumption. Nothing obvious. Whatever was doing this was clever - it didn't show up as a clear offender in any of the usual places. I checked recently installed apps. Nothing new. I checked running services. Nothing suspicious. It was hiding in plain sight.

The clue that cracked it

The breakthrough came from the status bar.

Buried among the usual notifications was a persistent message I'd been ignoring for days: "Your device is running securely."

That stopped me cold. Because I hadn't installed any security app on this tablet. Nothing should have been telling me my device was "running securely." That's not a standard Android message. Something was pretending to be a security tool.

I tapped the notification. It led back to an app called "Tiny Tasks." In the notification bar and when switching between apps, its icon was just a plain white square - the kind of thing you'd glance past and assume was a system process. Something official. Something you're not supposed to touch. But when I found it in the app drawer, it looked completely different - a cutesy little notepad with a checkbox. Friendly. Harmless. The kind of thing someone downloads once and forgets about.

Nobody in the family remembered installing it. Nobody knew what it did. And yet there it was, with full permissions, running constantly in the background, using a different face depending on where you looked.

I uninstalled it immediately. The change was instant. The tablet came back to life like someone had flipped a switch. No more ads. No more lag. No more mysterious notifications.

Then I kept going. If one rogue app had been hiding, what else was lurking? We went through every installed app and removed dozens that hadn't been opened in months. It was like clearing out a cupboard you'd been avoiding for years.

How a "normal" app turns on you

Here's the thing that unsettled me most: I don't think this app started out malicious.

It was almost certainly something innocent once - a utility or productivity tool that someone downloaded ages ago and forgot about. But at some point, it changed. Either the developer sold it, or the app was bought by someone with different intentions, or it was quietly updated with adware baked in.

This happens more often than people realise:

• Small apps get bought in bulk. A company buys a catalogue of apps with existing user bases, then pushes updates that inject ads or harvest data. The users never notice because they already trust the app.
• Developers go rogue. A developer running low on income adds an aggressive ad SDK to squeeze money from their existing users. What was a free, clean app becomes an ad machine overnight.
• Permissions creep. An app that originally needed access to your storage now wants your contacts, your location, your camera. Each update asks for a little more. Most people tap "Allow" without reading.

The original app on our tablet wasn't even called "Tiny Tasks" - whatever it had been is lost to time. It had been renamed, repurposed, and weaponised without anyone in our house knowing.

The other trick: apps that drain your wallet

While we're talking about dangerous apps, there's another flavour worth knowing about - and this one nearly got me.

My daughter was playing with my phone one afternoon. "Dad, can I download this app? It shows you what you'll look like when you're old!"

I was busy - distracted with work, emails, a dozen other things. The app looked harmless. High rating on the App Store. And most importantly, it was free. So I said yes. Within seconds she was laughing at an aged version of herself.

Then - a paywall. To unlock the "full feature," the app wanted a one-time fee of $100.

Except it wasn't a one-time fee. Buried in the fine print, it was a monthly subscription. $100. Every month. Automatically renewed. And in that moment, as a busy parent just wanting the nagging to stop, I almost tapped "Approve" without reading. That close.

These apps use a simple formula: lure you in with a free download, lock the real feature behind a paywall, make the cost look like a one-off when it's actually a subscription, and bet on you not noticing for months. They target kids and distracted parents specifically - a curious tap, a Face ID confirmation they don't fully understand, and suddenly you're paying $100 a month for a camera filter.

Time for an app spring clean

After our tablet incident, I now do this every couple of months. It takes about ten minutes and it's worth every second:

• Open your app list. On Android: Settings > Apps. On iPhone: Settings > General > iPhone Storage. Just scroll through. You'll be amazed how many apps you forgot existed.
• If you haven't used it in three months, remove it. You can always reinstall later if you need it. But every unused app is an unused attack surface.
• Check your subscriptions. On Android: Google Play > Payments & Subscriptions. On iPhone: Settings > your name > Subscriptions. Cancel anything you don't actively use.
• Review app permissions. Go through your installed apps and check what they have access to. Does that torch app really need your contacts? Does that recipe app need your microphone?
• Watch for apps you don't recognise. If something's on your device and you can't remember installing it - or it has a generic name like "System Service" or "Device Helper" - investigate before ignoring.

Red flags that an app has gone rogue

If you're wondering whether something on your device is misbehaving, here's what to look for:

• Your device is noticeably slower than it used to be
• Ads appear outside of apps - on your home screen, lock screen, or in your notification bar
• Your battery drains faster than usual
• Data usage spikes without explanation
• Notifications from apps you don't recognise, especially ones claiming your device is "secure" or "optimised"
• Apps have changed names or icons since you installed them

That last one is a dead giveaway. Legitimate apps don't quietly rename themselves.

The takeaway this week

The apps on your phone or tablet aren't just tools. They're guests in your digital home. And like any guest, if they start trashing the place, they need to go.

Don't wait for your device to slow to a crawl before you pay attention. A quick scroll through your app list once a month is one of the simplest, most effective security habits you can build.

If it's on your device and you don't know what it does - find out. Or remove it.

Stay safe out there,
Mat C

P.S. Right now, go to your phone's subscription settings and check what you're paying for. I've heard from readers who found subscriptions running for months they didn't even know about. Ten seconds of checking could save you real money.

P.P.S. Every time you sign up for a new app, you hand over your email address. If that app later gets sold, breached, or goes rogue - your real email goes with it. That's why I use SecureAlias for every app sign-up. One unique alias per app. If one starts spamming you, you know exactly which app leaked it - and you can kill the alias without touching your real address.