A previously undocumented attack group is using both custom and off-the-shelf malware to target IT providers in Saudi Arabia in what appear to be supply chain attacks with the end goal of compromising the IT providers’ customers. The group, which we are calling Tortoiseshell, has been active since at least July 2018. Symantec has identified a total of 11 organizations hit by the group, the majority of which are based in Saudi Arabia. In at least two organizations, evidence suggests that the attackers gained domain admin-level access.