The Sekhmet website said SilPac had been attacked on 20 June and data exfiltrated, in what is becoming a standard tactic.
Sekhmet only works on Windows systems as is the case with common ransomware.
The site said the company's data had been encrypted twice, once after specialists had begun restoring the initially encrypted data and making a bid to track the ransomware group.
"The only was sure-fire way to remediate in these cases is to rebuild the network. If companies do not do that, there is a chance that the actor will continue to have access to their network, monitor their response to the incident and possibly encrypt their data for a second time," added Callow who works for the New Zealand-headquartered security outfit Emsisoft.
On its blog, the people behind Sekhmet claim to be IT specialists and also say they are the only group that phones their victims to communicate, as email servers are often taken down by their attacks.
SilPac was founded in October 2000. The company has been contacted for comment through the only vehicle for communication it offers which is a Web form that is optimised for US- or Canada-specific details.
Sekhmet has released an archive of data which it claims is from SilPac, adding that a password for the archive will be released on 28 June.