Running in Circles: Uncovering the Clients of Cyberespionage Firm Circles

Circles is a surveillance firm that reportedly exploits weaknesses in the global mobile phone system to snoop on calls, texts, and the location of phones around the globe, and is affiliated with NSO Group, which develops the oft-abused Pegasus spyware. Using Internet scanning, we found a unique signature associated with the hostnames of Check Point firewalls used in Circles deployments, enabling us to identify Circles deployments in at least 25 countries.