Security vendor Symantec says it has discovered a Trojan that was designed to steal intellectual property from 50 specific companies, among the chemical manufacturers and defence contractors.

According to a report from Symantec, a Trojan called PoisonIvy was sent to the targetted companies via emaikls carrying an attachment claiming to be a security update.

Most of the infected computers were in the US, Bangladesh and the United Kingdom, the report said, although most of the targetted companies were US-based.

"Numerous targeted attack campaigns are occurring every week," the Symantec whitepaper said. "However, relative to the total number of attacks, few are fully disclosed."

Out of the 48 companies, a total of 29 are in the chemical industry, with another 19 "primarily from the defence sector". According to Symantec, the work of the infected companies includes research and development of chemical compounds and advanced materials; development of materials for military vehicles; and development of manufacturing infrastructure for the chemical and advanced materials industry.