Often on cheaper monitors, power is just supplied from the USB B input connector. I assume this is what you are saying?
Power is available inside, but, you need additional IC's and circuitry to use that to power USB ports, so costs a tiny bit more.
The manual just says "USB HUB x4 (v.3.0 DC5V, 900mA)"
I wouldn't screw around with the internals and just double sided tape a powered hub onto the back of the monitor or something.