In ubuntu for example, whilst booting, ubuntu starts loading more of the malware from the metacache which suggest the hard drive cache may have been filled by the initial boot loader for the malware, again helping to hide the malware from detection. When booting different OS's, it works with XP, Ubuntu, Parted Magic, Kali, Tails and others. The OS's seem to actively hide the malware if you use a hex editor to scan the drive or infected files, so over time, some of that open source code has become compromised, and lets not forget the Dirty Cow exploit has been around since 2007 potentially making it possible to hack many different packages that make up the core Linux OS. It also seems to use SNMP to hack into managed switches, so whether this is getting into the Stuxnet/DuQu/DuQu2 territory, remains to be seen, but I would suggest it is, this then narrows it down to one country, because in maths its possible to calculate unknowns.
Remember, software always does what its told, unlike Humans and here in lies its weakness!