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A Nefilim ransomware attack that locked up more than 100 systems stemmed from the compromise of an unmonitored account belonging to an employee who had died three months previously, researchers said. Nefilim (a.k.a. Nemty) is a ransomware strain that emerged in 2020, with its operators adopting the tactic that researchers call double extortion. In other words, Nefilim threatens to release victims’ data to the public if they fail to pay the ransom; it has its own leaks site called Corporate Leaks, which resides on a TOR node. Most famously, it attacked Australian transportation giant Toll Group early last year. According to Sophos researcher Michael Heller, this latest victim was compromised by exploiting vulnerable versions of Citrix software, after which the gang gained access to an admin account. From there, it stole the credentials for a domain admin account using Mimikatz. Nefilim Lurks for a Month, Stealing Data A Sophos forensic analysis found that the organization’s installed Citrix Storefront 7.15 CU3 was vulnerable at time of incident to a known critical security bug (CVE-2019-11634) and four high-severity issues (CVE-2019-13608, CVE-2020-8269, CVE-2020-8270, CVE-2020-8283). Storefront is an enterprise app store that employees can use to download approved applications. It’s almost certain, the team found, that this was the initial point of entry into the victim’s network. After exploiting the Citrix installation and establishing an initial foothold, the attackers…

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