APK files are the package files used to install applications on Android devices. They are similar to .exe files on Windows, and they contain all the necessary files for an application to run. It is possible to verify if apps installed via an APK file have been modified, but it requires a certain level of technical knowledge.The first step in checking if an APK file has been modified is to obtain the original version of the file. This can be done by downloading the original version from the Google Play Store or from the developer's website.
Once you have the original version, you can compare it to the version you have installed on your device.The next step is to use a tool such as ApkTool or Jadx to decompile the APK file. This will allow you to view the code of the application and compare it to the original version. If there are any discrepancies between the two versions, then it is likely that the APK file has been altered.It is also possible to use a tool such as ApkSigner to check if an APK file has been signed with a valid signature. If the signature is not valid, then it is likely that the APK file has been modified.Finally, it is possible to use a tool such as VirusTotal to scan an APK file for malicious code.
If any malicious code is detected, then it is likely that the APK file has been modified.In summary, it is possible to verify if apps installed via an APK file have been modified. However, it requires a certain level of technical knowledge and access to tools such as ApkTool, Jadx, ApkSigner, and VirusTotal.