An advanced persistent threat (APT) group based in China, code-named Suckfly, has been concealing its nefarious activity over the past two years by stealing code-signing certificates and applying them to malware and hack tools to make them look like legitimate software when downloaded.

According to a security blog post by Symantec, Suckfly stole the certificates from legitimate businesses in Seoul, Korea and used them to hide attacks against worldwide government and commercial entities beginning in early 2014. Symantec became aware of this plot in 2015 after discovering a hacking tool used against one of its clients was signed with a certificate.

Suckfly's cyber arsenal includes keyloggers, credential dumpers, port scanners and back doors, including one custom back door named Nidiran specifically developed for cyberespionage campaigns. Symantec traced the APT's activity to three IP addresses in Chengdu, China.