A close friend texted me this morning asking if I meant to send that last text, noting it was suspicious. I asked for a screenshot of the text in question, and it is a text from my number with spam I did not send. The text said "Visit http://legacy.operator.com:8080/webgui/vm[...] to read your new mms." and it appears in-line with the actual dialogue I'd had with this person.
From my phone, I see no record of sending that text. They received it around 10am, and at 11:30am I received a text from an unrecognized # with similar spam but in German. An odd coincidence or just a sign spammers were active all around. In any case, because of the difference in timing, at least the German text couldn't have infected me and caused the text to my friend.
Neither of us clicked either spam attack's link. I expect the German one I received can safely be ignored. I'm uncertain about the other text which my friend received from my # and which I have no record of sending.
Does the text my friend received from my number imply one of us has a virus? I'm concerned this is the case because either a virus on my phone sent spam out to the # I contact the most (this friend), or a virus on my friend's phone brought up spam spoofed from the # they contact the most (me). How else would the spammer know to spoof from my # to my friend's # - of all the #s it could go to/come from, my friend and I are each other's top contact.
If it does imply one of us has a virus as I suspect, is there a way to tell who, or do we each need to take antivirus cleanup measures? We both have Android phones and I think the same carrier but different phone models and OS versions. We both have antivirus on our phones (WebRoot on my end, Norton on my friend's) and scans came back clean.
Related but doesn't answer my question, just clarifies tech involved: