WASHINGTON—The U.S. Commerce Department added Israel’s NSO Group and Candiru to its trade blacklist on Wednesday, saying they sold spyware to foreign governments that used the equipment to target government officials, journalists, and others. Positive Technologies of Russia, and Computer Security Initiative Consultancy PTE LTD, from Singapore, were also listed. The Department said they trafficked in cyber tools used to gain unauthorized access to computer networks. The companies’ addition to the list, for engaging in activities contrary to U.S. national security or foreign policy interests, means that exports to them from U.S counterparts are restricted. It for instance makes it far harder for U.S. security researchers to sell them information about computer vulnerabilities. “We are not taking action against countries or governments where these entities are located,” said a spokesperson for the U.S. State Department. Suppliers will need to apply for a license before selling to them, which is likely …