Android virus spamming DOWNLOAD in Message+

If Stack Overflow isn't the right place to put this, then where is the right place? I have no idea how to look up this virus since I have little to go off of.

So I recently switched over to an AT&T SIM card (though that could be irrelevant) and started getting a crapton of random numbers from people with the same thing: a 0KB file with just the word "DOWNLOAD" boxed (see image). The first time I got one of these, I clicked on it because it was from a friend, but it was only after I had tapped download that I asked myself whether or not it was a virus and asked if he had meant to send me it. A bit of texting later led to the conclusion that he didn't know about it. I've gotten this from a dozen numbers, some I know, some I don't. I've asked one of the strangers and they didn't know anything. Eventually, my mother's number sent me one, and upon checking her phone, as with everyone else, it had never sent me anything of the sort.

What could it be?