Aeris appears to be an implant that is designed to allow an agent to retrieve and send information about the infected system through TLS encrypted channels.
And what would be that information? Our personal data, online passwords and data from the clouds? Or an entire file system?
Another question is why are only old distributions targeted. Don't forget about older Android versions, I think those too might be vulnerable.
EDIT: Someone might be spreading fear to force upgrades to new OS versions. My personal opinion.
Possible reason? It's the economy. New OS require newer hardware. If you push people to upgrade, they have to buy better machines. Right now, there are a lot of i368s all around the world, but new systems mostly don't support them. Which means people have to go to Walmart/anyMart to buy shiny x86/amd64s.
Likewise, the latest online products and services are reserved for 64-bit, many applications are outright dropping 32-bit support.