Recieved a fishy mms and I might be under stagefright attack

I haven't been able to use my phone for a day now. Or I'm afraid to use it.

I recieved an mms from a number that isn't registered on my contacts.
It contained a fake video play button picture on it. (Refer to the screenshot)

My mistakes are:
It's rooted
Only on kitkat
Didn't do any of those disabling the automatic retrieval of mms option

I couldn't update my phone against stagefright because it's only a generic gsm Chinese android phone.

Now I'm afraid that I may be under attack since I dont even have to open the mms message
Itself.

I removed the sim card and SD card and let my phone off.
I have private stuffs on my phone and I cannot let anyone meddling with it.


How am I gonna know If my phone is still safe to use or how am I gonna know if I'm under attack or not...

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