Federal agencies still reeling from the effects of a massive hack involving SolarWinds may face a new challenge of evicting any adversaries that breached their networks through recently discovered vulnerabilities in Microsoft's Exchange software. "Patching and mitigation is not remediation if the servers have already been compromised," the National Security Council said in a tweet on Friday. "It is essential that any organization with a vulnerable server take immediate measures to determine if they were already targeted." President Joe Biden's National Security Advisor Jake Sullivan also took to Twitter to urge U.S. think tanks and defense industrial base contractors "to patch ASAP."