ESET researchers analyzed previously unknown Linux backdoors that are connected to known Windows malware used by the China-aligned Gelsemium group, as well as to Project Wood.

ESET researchers have identified multiple samples of Linux backdoor, which we have named WolfsBane, that we attribute with high confidence to the Gelsemium advanced persistent threat (APT) group. This China-aligned threat actor has a known history dating back to 2014 and until now, there have been no public reports of Gelsemium using Linux malware. Additionally, we discovered another Linux backdoor, which we named FireWood. However, we cannot definitively link FireWood to other Gelsemium tools, and its presence in the analyzed archives might be coincidental. Thus, we attribute FireWood to Gelsemium with low confidence, considering it could be a tool shared among multiple China-aligned APT groups.