Hello Michał Kuniczuk,
Thanks for your question.
There is a policy on permissible penetration testing. You can take a look at these guidelines to avoid violating terms of service. See:
https://www.microsoft.com/en-us/msrc/pentest-rules-of-engagement
Also see Service Agreements:
https://azure.microsoft.com/en-us/support/legal/
You can mark it 'Accept Answer' and 'Upvote' if this helped you
Regards,
Abiola