Spearphishing is a method used by hackers to attack a particular person or organization by sending email or other electronic communications. The goal is to steal data or other malicious purposes such as installing malware on the victim's computer.
The attacks were Lazarus's attempt to slip the malware into the victim's computer by sending a Word file that looked harmless. The file will ask the recipient to enable editing feature to view the document.
If the recipient activates the feature, the file will activate a macro that will activate the trojan to penetrate the PC system secretly.
Secureworks analysts have seen this attack in early 2016, while the latest attack took place in November.
They also added, possibly, these attacks are still continuing and the reports they provide are only preliminary reports. Going forward, they will probably make a more complete report.