ExtraPulsar is a backdoor Trojan that is used by criminals to collect information from the computers it manages to infect. ExtraPulsar is based on a VSA code that leaked in 2017. ExtraPulsar, instead of exploiting vulnerabilities, uses a Microsoft file server driver, SRVNET.SYS to gain access to a computer. ExtraPulsar can perform certain tasks that will change computers running the Windows operating system, as well as Windows servers to make them enable file sharing, which can harm the machine's data.
Backdoor Trojans are very threatening since they can allow third parties to take full control of a machine and perform multiple actions that will not benefit the computer owner. This is what makes maintaining your software always updated by applying patches and using a competent scanner to detect any threat that may be hiding inside it a must do no matter if the machine belongs to a private owner or a huge corporation.