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Avast Mobile Security: Erratic Performance

Avast Mobile Security has solid malware protection, but some of its many features don't work well.

Our Verdict

Avast Mobile Security has solid malware protection, but some of its many features don't work well.


  • Inexpensive pro version
  • Highly customizable
  • Feature-rich free version


  • Call blocking didn’t work
  • Anti-theft feature not reliable
  • Lengthy setup process
  • Ads in free version can get annoying

Avast Mobile Security, also known as Avast Mobile Security & Antivirus, has more than 100 million downloads and a solid 4.5 user rating in Google Play, and it was our Editor's Choice for Best Android Security App in 2014 and 2015. 

We liked its huge assortment of powerful anti-theft and privacy tools (including some for rooted phones only), and its good, if not quite perfect, malware-detection rate.

Avast's mobile protection has gone through some changes in the last couple of years. Things got a little bumpy in our testing last year, when the app went to a completely free ad-supported model but lost ground with a lower malware-detection rate and heavier system impact. Avast even discontinued a few of our favorite unique features.

This year, we again see Avast changing things up, with a return to a freemium model. There's  once again a Pro tier delivering an ad-free experience for those who want it.

The malware-detection rate for the app has recovered somewhat, becoming more consistent even if it still isn't quite perfect. But the call blocker didn't work, and the anti-theft features, while powerful, had trouble connecting to the Avast web portal.

For users looking for a free solution, we now recommend the free version of Norton Mobile Security. If you’re willing to pay, Bitdefender Mobile Security is your top bet overall among the best Android antivirus apps.

MORE: Best Antivirus Software and Apps

Costs and What's Covered

In the past, the core Avast app was free (with ads) and only some of the add-on apps were paid. Now, the core app has added a premium tier that brings with it some new features and benefits for $1.99 a month, or $7.99 a year.

Some of the benefits of the premium plan include the robust Anti-Theft features, App Locking (formerly a separate paid app), removal of ads from the app, and direct support from Avast within the app.

Avast's premium pricing is fairly inexpensive, at first glance. Most other premium Android security apps are at least $15 per year. But unlike the others, Avast continues to break out some of the extra features into separate apps, with varying pricing schemes among them.

The Wi-Fi Finder is the only app left in Avast’s lineup that remains completely free, with no option to upgrade. Battery Saver and Cleanup & Boost have followed in the freemium footsteps of Security & Antivirus with a free basic feature set, and a premium or pro upgrade that removes the ads and delivers a couple of additional features.

Finally, Avast offers its SecureLine VPN app with a seven-day or 14-day free trial, depending on whether the user opts for a monthly or yearly plan. When the trial is up, the user is charged either $2.59 per month or $19.99 per year, respectively.

Malware Protection

Avast puts malware scanning front and center with its app. The very first thing you see at the top of the screen when you open the app is a big green button that just says "SCAN."

Unfortunately, the scan itself was one of the slowest in our testing. It took between 45 seconds to a full minute for a scan to complete. The app allows users to schedule scans by both day and time, so you can sleep right through this slower-than-average scan when it runs at 4 a.m. every morning.

Avast’s Web Shield protects you while you are browsing the web. It works with the native Android browser, Chrome, the Amazon Silk browser, the Boat Browser or the Boat Browser mini. I attempted to visit multiple malicious sites, but the browser successfully identified and stopped me from reaching them.

Malware Performance

Avast Mobile Security received solid marks from the German independent lab AV-TEST's most recent evaluations of Android security products, conducted in September 2017. The app detected 99.8 percent of the 3,016 "real-time" malware threats used, and 100 percent of the 2,917 samples that had been collected in the previous four weeks.

These scores aren't perfect, but they're very good. They also beat the average detection rates of 95.7 of real-time, and 98.4 percent of recently discovered, threats among the 21 Android security products AV-TEST tested in September.

I attempted to receive calls from blocked contacts and from private numbers, and both kinds of calls came through as normal.

Among the four other Android antivirus apps we reviewed that submitted their apps to AV-TEST, Bitdefender Mobile Security, CM Security Masterand Norton Mobile Security each had a 100/100 percent detection rate in September, followed by PSafe DFNDR (99.7/100 percent).

Avast's malware-detection rates are more consistent than those of some other vendors. In July 2017, Avast scored 99.8/99.9 percent; in May 2017, it scored 99.5/99.9 percent; in March 2017, it got 99.9/99.8 percent; in January 2017, 99.8/99.9 percent.

By contrast, CM Security's rates fluctuated from highs of 100/100 percent in May and September to a low of 99.0/99.3 percent in July; PSafe DFNDR's detection rates varied even more, bottoming out at 96.3/97.2 percent in March. (Bitdefender's and Norton's rates were more consistent, hovering around 100/100 percent throughout.)

Lookout Security & Antivirus is the lone antivirus app we tested that no longer submits its app to AV-TEST for evaluation.


Call Blocker
This feature basically retains the same feature set as when I tested it last year. It allows users to create a blacklist that blocks either specific phone numbers or categories of numbers, and, unfortunately, it was exactly as unreliable in real-world testing as it was last year.

I attempted to receive calls from blocked contacts and from private numbers, and both kinds of calls came through as normal, which shouldn't have happened. Again, the only setting that I was able to get to work was the blocking of specific area codes. This remains a good-looking feature that in practice simply doesn't work.

App Permissions
This feature, also referred to as Privacy Advisor, scans your installed apps for the the system permissions each takes and provides a list sorted into high, average or low permissions. It provides a bit more information, specifically regarding permissions and ad networks, than what you can see in the main Android settings menu.

Users may find App Permissions useful as a way to take a look at some of the worst privilege offenders. Assuming you are running Android 6.0 Marshmallow or later, you can then move over to the app in your settings menu and disable some permissions if you feel that an app is overstepping its bounds.

Our primary complaint with this kind of feature from any antivirus app is that it ignores Android 6.0 Marshmallow's ability to restrict individual permissions, which means the app often makes incorrect assumptions regarding which permissions an app has been granted.

After marveling that this feature wasn't built into the core Avast app last year, I was pleased to see that the company did exactly that in the interim and did away with the stand-alone anti-theft app.

I would not trust this app for a mission-critical task like anti-theft.

Avast's remains by far the most powerful anti-theft offering of any antivirus app that I tested. The sheer number of features available to Avast users in this area is remarkable for both free and Pro users, with a lack of SMS commands being the only obvious omission.

Now for the bad news: This year I experienced even greater connectivity issues with the web portal than I did last year. The portal would simply report that it was unable to connect to my phone, sometimes for hours, even when I was viewing the portal on a computer in the same room and on the same Wi-Fi network as the phone.

It’s an issue I haven’t seen once with any of the other antivirus apps that offers anti-theft features, or with Android’s built-in Find My Device feature. Obviously, this drastically undermines the value of Avast's anti-theft feature. It'll cover what is available when everything is working properly, but please be aware that I would not trust this app for a mission-critical task like antitheft.

The standard anti-theft options are naturally all present, including the ability to locate, lock and wipe the device, and to trigger a siren. The command to track the device automatically triggers location requests at regular intervals, which can be set to be as frequent as every 5 minutes.

The Mark as Lost function is a combination of the above commands -- it tracks and locks the device, fires off the siren and disables USB debugging so that the phone can't be meddled with.

Getting into the more unusual capabilities of the the anti-theft feature, there is the ability to forward all calls or texts sent to the device to another number.  Texts can either be duplicated on the stolen/missing device or only sent to the new number. While most Android users will have their contacts backed up by Google, you nonetheless can issue a command to download your contacts, calls and SMS from your phone.

The last category of anti-theft commands involve contacting the device directly. You can do this either with a customized message that will display on the device or by forcing the device to call a phone number of your choosing. The app attempts to hide this call, so it's up to you whether you use this feature to speak to the individual who has your phone number, or just to listen in on them.

Only rooted phones can use this feature, which allows you to control internet access for individual apps. You can either block an app's internet access entirely or block internet access to the app anytime the device isn’t on Wi-Fi. I was unable to test this feature as I did not possess a rooted device at the time of the review.


Paid users of Avast Mobile Security get three additional anti-theft functions. The first captures photos of the individual holding your device when an incorrect lock-screen PIN is entered.

Our performance impact results put Avast Mobile Security in second place with just the app installed, but in last place during a malware scan.

Second, removal  of a SIM card can be set to trigger the Mark as Lost command, which begins tracking the device, locks the device, sets off the siren and disables USB debugging. Finally, paid users are able to activate the microphone on the device to record ambient audio for set durations when noise is detected.

App Locker
Avast has made some much-needed updates to this feature since I reviewed it last year. Most critically, support for using the fingerprint scanner to unlock individual apps was introduced, with a PIN required only during setup as a fallback option.

Last year, I was able to see the contents of an app before the app-lock screen showed up. That notable glitch is now gone.

Setup of the App Locker feature remains an area in which Avast could use some help. While Avast does provide recommendations regarding which apps you might want to lock, it doesn’t give you the option to just go ahead and apply those recommendations. It's a one-time thing to go through and toggle the switches for the apps you want to lock. Nonetheless, it feels a little cumbersome that the Avast app won’t do it for you, as some of the other app lockers tested could.

Avast Direct Support
Lack of support is typically one of the downsides of free software, so it’s of little surprise to see tech support bundled into Avast's paid version. Notably, Avast merely promises prioritized support for paid users, so you’ll get to the front of the line but won't get any guarantees that an answer will be forthcoming immediately.


SecureLine VPN
Avast's stand-alone virtual-private-network app works well with the rest of the Avast mobile suite. The straightforward interface will have you connected to either the most optimal VPN server available, or to a server in the country of your choice if you are looking to avoid regional restrictions. In my testing, the connection held reliably and was typically working in under 2 seconds.

At $1.99 a month, or $19.99 a year, for just a single device, SecureLine VPN isn’t a terrible value. But unless you really want the integration with Avast, or need the VPN service only for your smartphone, there are better options out there. Take a look at our Best VPN Services and Apps of 2017 for a few recommendations to consider.

Wi-Fi Finder
If you are constantly on the search for a reliable open Wi-Fi connection, this tool is potentially for you. The app displays nearby Wi-Fi networks on a map and integrates with SecureLine VPN to protect you in the event that it is an unsecured network.

While I’m familiar enough with the Wi-Fi networks in my area, and there are quite a few that went under the Avast app's radar, I could see this being a very useful feature while traveling.

System Impact

To evaluate the performance impact of constantly running Avast Mobile Security in the background, I ran multiple tests using the Geekbench 4 Android benchmarking tool on my Samsung Galaxy S8 running Android 7.0 Nougat.

Following installation of Avast Mobile Security, the phone's performance scored 0.39 percent lower than its baseline average on the Geekbench 4 test. During a full scan, it scored 7.35 percent below its baseline performance.

These results put Avast Mobile Security in second place for performance impact with the app installed, but in last place for performance impact during a malware scan. Bitdefender Mobile Security had the least system impact during a scan.

Setup and Support

The overall setup time for Avast was rivaled only by CM Security Master. With all of the various settings and additional apps to install, it was approximately 10 minutes from start to finish. While this is obviously a one-time concern, it doesn’t make the best first impression.

There are portions of the installation that are quite well-handled. When users are required to grant specific permissions or toggle device settings to get the app working properly, there are helpful animations to walk them through the process. However, there were more than a couple of moments when I was at a loss for what I was meant to be doing next, and I’ve been through the Avast setup process more than a couple of times now.

Avast's user support is handled mostly through a series of FAQs and a moderated forum. The FAQs are quite good if they happen to hit on your precise issue, and the latter isn’t as well-moderated as it once was, but remains reasonably active.

The last resort for users is email support, and this is presumably where the priority treatment for paid users comes into play. But the lack of a more instantaneous form of support, such as via online chat or phone, is frustrating when you run into an issue that simply isn’t already covered anywhere.


After having used heavily simple images in the background of each screen in the core app last year, Avast has now stripped things down across the lineup, with either pure white backgrounds or basic gradients.

While I was kind of fond of the imagery used, I can understand that it may not have been a hit with everyone.

The only holdout is SecureLine VPN, which has a simple line-art cityscape in the background. But given its virtually empty interface, having something to look at in the app makes sense.

Looking beyond the Avast app's appearance to its usability, things have improved, but that is likely due to my spending most of my time using the Pro version, which does away with ads.

For the most part, you will find the options you are looking for immediately, without scrolling. Moving down the screen usually just sucks you into extra features or ads. While the apps are occasionally a mashup of a few different Material Design standards, they stick reliably enough to the familiar navigation schemes that you will find your way.

Hopefully, this new pricing model will work for Avast, and the company will get a chance to further refine the new design without having to do yet another ground-up rethink before next year.

Bottom Line

Avast Mobile Security remains one of the most customizable and comprehensive Android antivirus offerings on the market, and many of its individual components or add-ons are best-in-class regarding user interface and implementation. Its malware-detection rate has returned to its former level, even though that's a notch below perfect.

However, we ran into several problems, with some of those features simply failing to work reliably, including the otherwise amazing anti-theft features. With a security product, that is simply not acceptable.

While its overall feature set is less compelling that Avast's, we recommend Norton Mobile Security as the best free Android antivirus app, both for its malware performance and for the reliability of its features . However, if you're willing to pay for Android malware protection, we recommend Bitdefender Mobile Security.

Credit: Sean Riley/Tom's Guide