CARBIS BAY, England—The Group of Seven (G-7) wealthy nations on Sunday demanded Russia take action against those conducting cyberattacks and using ransomware from within its borders. The rebuke came in a communique issued after a three-day summit of G-7 leaders in the United Kingdom that also called on Moscow to “stop its destabilizing behavior and malign activities” and conduct an investigation into the use of chemical weapons on Russian soil. The communique said Russia must “hold to account those within its borders who conduct ransomware attacks, abuse virtual currency to launder ransoms, and other cybercrimes.” The issue is in the spotlight after a cyberattack on Colonial Pipeline, the largest fuel pipeline in the United States, and another that disrupted the North American and Australian operations of meatpacker JBS USA. The UK has previously said Russia is a leading proponent of cyberattacks. The G-7 statement called for wider action against ransomware …