9Game.com, a portal for downloading free Android games, was identified as the mobile app store hosting the most malicious apps in 2019.
9Game ranked number one on the list of app stores with the most "new" malicious app uploads, but also number one on the list of app stores with the highest concentration of malicious apps overall.
According to RiskIQ's 2019 Mobile App Threat Landscape report, 61,669 new malicious apps were uploaded on 9Game in 2019.
In this ranking, 9Game was followed at a considerable distance by the official Android app store -- the Google Play Store -- with 25,647 new malicious apps. Completing the top 5 are Qihoo 360's Zhushou store, feral apps (a term used to describe apps published outside of any app store, usually on web pages or forums), and Huawei's Vmall app store.
But while the Play Store ranked second on the list of new malware uploads, its sheer size diluted the impact these malicious apps had on Android users.
The Play Store didn't rank at all in the top 5 app stores with the highest concentration of malicious apps, which included (1) 9Game, (2) the feral apps, (3) the Vmall app store, (4) the Xiaomi app store, and (5) Qihoo 360's Zhushou store.
RiskIQ: Apple treats its App Store like Fort Knox
One notable absence on this list is Apple's App Store. This is a direct result of Apple's in-depth and individual app review process, which is more suited to catching malicious apps than the automated process employed by most other app stores.
"Apple treats its App Store like Fort Knox and rarely hosts dangerous apps," RiskIQ said.
"Meanwhile, Google's security controls are improving despite allowing troublesome apps to enter the Play Store at a rate it finds acceptable-the number of blacklisted apps in the Play store dropped an impressive 76.4% in 2019," the security firm added.
All in all, RiskIQ says the number of malicious apps observed globally in 2019 dropped 20%, from 213,279 in 2018 to 170,796.
Most new apps appear in China
The downward trend is surprising, RiskIQ experts said, as there are now more apps than ever. The company said it observed 8.9 million new apps uploaded on app stores globally in 2019, 18% more than in 2018, when it detected 7.5 million new apps.
RiskIQ says that most of these new apps (both clean and malicious) are coming from Chinese developers.
According to RiskIQ, the top 3 mobile app stores last year in terms of new app uploads were all from China. The list includes APK GK (1,687,757 new apps), APK Pure (890,479 new apps), and Android Apps APK (809,818 new apps).
Google (714,678 new apps) and Apple (465,676 new apps) only ranked fourth and fifth, respectively.
Updated on March 2 to remove a link to the Feral app store. This writer misconstrued the term "feral apps" as apps hosted on the Feral app store, rather than apps stored outside of any app store. ZDNet regrets the error.