I received an incomprehensible message, is the attacker exploiting a vulnerability?

Question

Android

Now I received an SMS from [phone] with the following text:

3ADAA
43753449C5AA136B6825133
2AA

(this is how the message on the phone's display looks like)
The phone is old, from Nokia with Symbian OS inside. I used to have Android Kit Kat, but the phone has been in repair for a week now. Previously, it used to come to the phone with android windows, such as "Android games: Mega racing in 7D, Zombie pigs, etc." without the cost of sending SMS to some number. If you click on ok, then a subscription for 15-30 rubles appears without warning. Megaphone operator.

Answer 1

Go to your personal account on the Megafon website and turn off the ability to receive SMS in principle and there will be no more such situations

Answer 2

Go to your personal account on the Megafon website and turn off the possibilities of paid subscriptions in principle.

Answer 3

Go to your personal account on the Megafon website and turn on the service "refusal of paid ..."