Oh yea, that's DEFINITELY mites! (I had them last summer... They killed quite a few of my orchids, they r evil!) and if they've gotten this bad, you need the strongest possible defense, ASAP, although I don't know what you can buy in Malaysia...
**You need a miticide, & it should be systemic (meaning it goes thru the leaves/roots all throughout the plant tissue, and stays there for a little while, & kills anything that feeds on the plant!
).
I will look around, and get back to you, hopefully I can find something!? Cuz this is a bad infestation.
If you have an orchid nursery or even just a regular plant nursery nearby, you can ask them if they have any of the "big guns" to kill mites, and if they would spray your plants for you, or give you some spray to take with you, so you can spray them? (just don't bring your plants into their nursery w/o an "ok" from them, u wouldn't wanna infest their nursery w/ mites... They travel REALLY well! And kill REALLY well too!
)
If you can, separate all the infested plants (and all the ones around the ones that look infested) from your others, but mites can hide very very easily, so be careful. Most of the time, when you
see the mite damage, they have moved on to greener pastures, so isolate
all of the ones nearby. Try rinsing or spraying the (undersides of) leaves with (straight, undiluted) isopropyl alcohol, on as many plants as you can, every other day. *Keep them in a warm place when doing this, b/c as the alcohol dries, it cools the leaves (b/c it dries rapidly, evaporative cooling), & that can also be stressful to the damaged orchids.
When u get the miticide to treat them with, spray EVERYTHING!! You could (& most likely do) have mites on ALL of your plants, even if they aren't showing any damage at all!