WASHINGTON (Reuters) -WhatsApp said Friday it discovered an advanced cyberespionage effort that took advantage of a chain of security vulnerabilities in the app and Apple devices to hack them. A researcher with Amnesty International said unidentified members of civic groups appeared to be among those impacted. In a brief statement, the Meta Platforms-owned communications service said it had patched the security vulnerability that allowed hackers to take advantage of a second vulnerability on Apple devices and hijack the machines.