Why do I have a white page in the admin panel?

Question

1C-Bitrix

Everything falls on the line $GLOBALS["APPLICATION"]->AuthForm($arAuthResult); in the file bitrix/modules/main/include.php
Malicious code was also noticed in the files

Answer 1

Check the file manually. Most likely a malicious code was entered.
In any case, I recommend contacting Bitrix technical support or partners to find out the reason, since the question is too abstract, and there can be many reasons for the problem.