My father said to me that he allowed installation of apps from unknown sources when he was asked to do it to go further with something (he said that don't remember when or what he was doing).
In android 8.0 (the version of him smartphone) we can allow third-party installation in individually apps, so I went in this tab and I saw that only Google Chrome was able to this type of installation. So, I navegate through my father's apps and found nothing suspicious.
When I went to files, I found a folder called didi. Inside, a file with no extention called psnger_encrypted or something like this. When I went select the file to see details, I accidentally clicked on the file. Android said to me that was not found any app to open that file.
Could a file have been executed even when Android says that message? If this file is malicious, it is possible that has executed and so infected the phone?
Doing some research, I found that a chinese app called "DiDi" that have a file called "psnger" too. Also, I found a file in my father's phone called .omega.key, and this file is also seen in topics related to DiDi app. The fact is that I can't find this app on the phone, and I'm looking for ways that can indicate if the phone is infected. I executed AVG, and Malwarebytes but both detected nothing. What else can I do?