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You can sideload an Android app or manually install its APK package if you’re running a modified version of Android that doesn’t include Google’s Play Store. The app may also be experimental, in development, or perhaps no longer maintained and offered by the developer. Up until now, the existence of sideload-ready APKs on the web seemed to be something that was tolerated, though warned against, by Google.
That silent halt is being disrupted by a new feature in Google’s Play Integrity API. As reported by Android Authority, developer tools to push “remediation” dialogs during sideloading, which debuted at Google’s I/O conference in May, have now appeared on users’ phones. Sideloaders of apps from British retailer Tesco, fandom app BeyBlade X, and ChatGPT have reported “Remove this app from Play” prompts that cannot be bypassed. An Android gaming handheld user was met with a similar prompt from Diablo Immortal three months ago on their device.
Google’s Play Integrity API is how apps previously blocked access when loaded on phones that had been modified in some way from a stock operating system with all Google Play integrations intact. Recently, a popular two-factor authentication app blocked access on rooted phones, including the security-focused GrapheneOS. Apps can call the Play Integrity API and get back an “integrity verdict” that tells them whether the phone has a “trustworthy” software environment, has Google Play Protect enabled, and passes other software checks.
Graphene has questioned the validity of Google’s Integrity API and SafetyNet Attestation systems, and recommends standard Android hardware attestation instead. Rahman notes that apps don’t have to take an all-or-nothing approach to integrity checking. Rather than blocking installation outright, apps could only call the API during sensitive actions, and raise a warning there. But the lack of a Play Store connection could also rob developers of metrics, allow installation on incompatible devices (and resulting bad reviews), and of course open the door to paid app piracy.
‘Unknown distribution channels’ blocked
Google’s developer video on “Automatic Integrity Protection” (at the 12-minute, 24-second mark on YouTube) notes that “select” apps have access to automatic protection. This adds an automated checking tool to your app and “the strongest version of Google Play’s anti-tamper protection.” “If users get your protected app from an unknown distribution channel,” a slide in the presentation reads, “they’ll be prompted to get it from Google Play,” available to “select Play Partners.”
Last year, Google introduced malware scanning of sideloaded apps at the point of installation. Google and Apple have spoken out against legislation that would extend sideloading rights to smartphone owners, citing security and reliability concerns. European regulators forced Apple earlier this year to allow sideloading of apps and app stores, but with fees and geographic restrictions.
