First thing is to determine your tax residency
i.e. where you stay for more than 60/90/180 days. If you got any kind of PR then check double tax treaty.

But you contract work is definitely taxable, just depends on which country's tax you will pay. I'm incline to say you have to pay in Malaysia given the limited info.

Nowadays, it's harder to hide from tax because they have access to your bank account. Unless your employee pays you in bit coin, hard cash or something with no train in the system.