The only junk on your phone is your "junk cleaner" app, and here's the proof


As it currently stands, Google Play is the largest mobile storefront in the world, being host to more than 2.2 million apps, just slightly more than what Apple’s App Store offers. Yet you don't see Google gloating about it much these days, despite the two companies' endless rivalry – but why? Here's a theory: in reality, that number is not a win but a disaster, and the big G knows it. And the reason for that is simple – those two million apps? Most of them are garbage.

It really is remarkable just how awful the depths of the Play Store can get and just how little policing actually occurs during Google’s app vetting process. Just search for any semi-popular app and scroll down – there, you'll find all the knockoffs with a suspiciously similar name, the copious amount of “guides” for the app, the so-called extensions which do pretty much nothing useful, and so on. Each one of these had to be approved to get to the storefront, and apparently did so without a hitch. And let’s not even start with all the malware incidents during the platform's relatively short life. What we want to discuss here, though, is something else entirely - while all of the above are real problems, most of the time they're not famous enough to warrant discussion.

However, there exists a specific type of app that somehow manages to be extremely popular despite being blatantly deceitful to its users - the so-called "cleaners", "boosters", and/or "antiviruses". Looking at a list of popular apps reveals that these so-called utilities consistently get high install rates and glowing reviews, which to us is very suspicious. So we decided to do a little investigating into what these apps actually do and why they're so popular.

Mind you, the tests we performed were far from scientific, but even then, every one of the apps we chose was obviously designed specifically to take advantage of its users, while providing no useful functionality in return. Unless you count riddling your phone with adware as useful, of course – there was plenty of that.

The existence of such scam apps is not surprising in the least – for as long as the Internet has been around, there’s been plenty of people willing to take advantage of users’ lack of technical prowess. Remember BonziBuddy? It was a piece of software, most famously in the form of a purple monkey, which was supposed to help users navigate the Web. Also, it was a nasty piece of adware, littering its users’ desktops with unwanted advertisements. The case here is almost the same, except the monkey is, thankfully, nowhere in sight – these apps advertise themselves as a real, useful utility, but in reality serve mostly as a vehicle for serving a ton of ads.

So it seems logical Google would want to get rid of such scam apps, wouldn’t it? Yes, and that’s precisely… wait, what?

How naïve of us to think a billion-dollar corporation would actually care for its users - no, the reality is that these apps rake in a ton of cash, and Google, their biggest ad provider, gets a significant cut of it. So it’s only natural for the company to want to promote them, nevermind affected consumers.

And here’s the saddest part – users love it. Just a glance at the reviews shows thousands upon thousands of misguided recommendations, with only the occasional 1-star reviewer seeing through the lies (though undoubtedly a large number of the positive reviews are fake). A particularly curious case, for example, is the one where a user was warned by their carrier about a certain junk cleaner actually being adware, which prompted them to leave a negative review on the store page. An extremely vague reply by the developer, however, was apparently enough to reverse the user’s opinion, who then proceeds to actually thank the devs. And this is just a single example - such apps are commonly advertised with misleading ads designed to scare the user into thinking they're at risk, prompting them to install a needless piece of software.

But it isn’t just Google’s fault, really – for this whole genre of scam apps to be as successful, there must be people willing to use them. And this is precisely where decades of marketing come into play – it wasn’t so long ago when a computer without some sort of antivirus installed was considered pretty much unusable online. This paranoid line of thinking – that one is always threatened online, that there’s always something wrong with their machine – seems to have stuck through the years, and now is precisely what scammers are banking on.


We analyzed five of the most popular “cleaner” apps on the Play Store, chosen from the daily list of most downloaded apps, as provided by AppAnnie. Each app was installed on a freshly reset Blu Vivo XL running Android 5.1 Lollipop. All traffic on the device was captured using Fiddler, a free network analysis tool. We spent a few minutes with each app, trying out most of its advertised features, save for those which required creating a user account or installing a separate app. 

Clean Master

The most popular app of this kind on the Play Store, Clean Master is made by the infamous Chinese developer Cheetah Mobile. Advertised features of the app include: junk file cleaning, phone boosting, antivirus, CPU cooling, and more! Actual features, however, are mostly the following: ads inside the app; ads on a second lock screen, which Clean Master labels “Charge Master” for whatever reason; ads injected into webpages when using the “safe browsing” feature; and also the constant downloading of even more ads, including videos, most of which we never actually encountered during our time with the app. Massive points for effort, however – the app almost has a few cool features, and can actually be described as somewhat pretty, though both points are quickly diminished by all the lies about "cleaning junk" and "CPU cooling". In our test, one of the first things the app did was to access several very questionable domains, including ones linked to porn and gambling sites.


It turns out math is a much more malleable concept than we previously thought, and it’s the folks at PSafe we have to thank for the realization – somehow DFNDR managed to give us “700MB speed-up memory”, despite free RAM staying at almost the same amount before and after the app’s usage. The same thing happened with its junk data removal tool, which did absolutely nothing. For what it’s worth, however, its “antivirus” did send some data to a web scanning service, but most of the time the scan consisted of downloading ads. A user review on the Play Store described the pop-up ads as “predictable”, which is nice! - it’s good knowing exactly when you’re going to be taken advantage of, in return for a mostly nonfunctional service.

Junk Cleaner

One of the two apps with the same name on the list, Junk Cleaner apparently aims to be as unobstructive as possible, immediately removing itself from the app list and becoming accessible exclusively through a persistent notification (convenient!) A feature sorely missed, however, is the decimal comma, a.k.a. the difference between 434 MB and 4.34 MB of deleted data – though this is surely just an oversight to be fixed in a future update. We can’t give it enough praise, so we’ll let its store page description do the talking: “Most of Android users suffered from the phone lagging and insufficient memory when they using their phone, if you are looking for a cleaner for your phone, Junk Cleaner will be your best choice. Free to try it now!”

SUPO Security

An app so secure, it becomes inaccessible after just one use – truly revolutionary. We actually had to install it twice, as the first time it somehow blocked access to the Play Store, while also deleting almost all traces of itself. What was left, though, were tha app's background services, which pinged the servers of QQ, a popular Chinese chat service, once every two seconds. Many users also report being bombarded with apps after installing the app, though we did not share that experience. A fun quirk of the app is just how hard it is to remove, since it asks for permissions which can effectively disable uninstalling the app, unless one knows exactly where to look.

Junk Cleaner / Junk Cleaner Lite

In the words of the developer: “Junk cleaner, professional optimize your phone performance. Make your device running like new again.” We actually started with the Lite version of the app, but quickly found ourselves wanting more functionality, of which we got plenty – though most of it consisted of, you guessed it, ads. Just like Clean Master, here we got a few problematic ad sources, including one previously linked to the distribution of Android malware, along with a ton of pop-ups, and a lock screen overlay (filled with ads, obviously). Interestingly enough, this app actually reported less RAM usage than there really was, which seems counterproductive in an app designed to lie about cleaning memory.


Unfortunately for everyone, the popularity of scam apps just like the ones we looked at is only growing bigger, in large part thanks to Google, which actively promotes them to Play Store users, along with the many device vendors who preinstall them on their phones. Even though we only tested five of the so-called "cleaner" apps, we encountered many, many more of them further down the popular apps list. When even the most widely used ones are, as we found out, complete scams, they quickly become indicative of the overall climate in this particular app niche, so while we cannot discount the existence of actual applications performing such services as advertised, we still recommend you avoid using them like the plague.

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