Security firm Symantec said the use of legacy versions of Windows like XP in these sectors was one reason why they were being targeted.
There was some confusion in the company's blog post about Orangeworm with claims that it was both "a previously unknown group" and also that it was "first identified in January 2015". Obviously both these statements could not be true.
Known victims were said to include healthcare providers, pharmaceutical companies, IT solution providers for healthcare and equipment manufacturers that serve the healthcare industry.
The Kwampirs malware was found on machines that had software installed for using and controlling imaging devices like X-Ray and MRI machines.
The malware was also found on devices used to assist patients in completing consent forms for required procedures.
Symantec said the largest proportion of attacks observed were in the US: about 17%. "While Orangeworm has impacted only a small set of victims in 2016 and 2017 according to Symantec telemetry, we have seen infections in multiple countries due to the nature of the victims operating large international corporations," it added.
The company said it was able to rule out the involvement of any nation state in the attacks.
After infiltrating a victim's network, the Kwampirs backdoor was dropped; it ensured that it became a persistent service that would start on a reboot.
The method of propagation was described as "noisy", indicating that the people behind the attack did not really care whether the infection was discovered or not.
Kwampirs spread by copying itself over network shares, a method that is rather old; on this Symantec commented, "This method has likely proved effective within the healthcare industry, which may run legacy systems on older platforms designed for the medical community. Older systems like Windows XP are much more likely to be prevalent within this industry."
Kwampirs also cycled through a list of command and control servers until it established a connection, once again an act that is noticeable.
"The fact that little has changed with the internals of Kwampirs since its first discovery may also indicate that previous mitigation methods against the malware have been unsuccessful, and that the attackers have been able to reach their intended targets despite defenders being aware of their presence within their network," Symantec noted.
It said there were no technical or operational indicators that would enable it to pronounce on Orangeworm's origin.