U.S. nuclear weapons agency affected by cyber attack

The National Nuclear Security Administration (NNSA), the critical agency overseeing the U.S. nuclear weapons stockpile, has been impacted by a widespread cyberattack leveraging vulnerabilities in Microsoft’s SharePoint software. The breach, attributed by Microsoft to three Chinese state-sponsored hacking groups, affected over 100 organizations globally, including various government agencies and private entities.

The cyber offensive, which began exploiting SharePoint vulnerabilities as early as July 7, saw hackers bypass initial security patches released by Microsoft on July 8. The vulnerability, dubbed “ToolShell” by researchers, allowed the attackers to steal sign-in credentials, including usernames, passwords, and authentication tokens. Cybersecurity firms have detected compromises on hundreds of servers across numerous countries.

While sources familiar with the investigation indicate that no sensitive or classified information related to the U.S. nuclear arsenal was compromised during the NNSA breach, the incident has raised significant concerns within national security circles. The NNSA, a semi-autonomous arm of the Department of Energy, is responsible for the design, maintenance, and dismantling of the nation’s nuclear weapons, as well as providing nuclear reactors for Navy submarines and responding to radiological emergencies.

The Department of Energy acknowledged that its systems were “minimally impacted” due to its extensive use of Microsoft 365 cloud services and robust cybersecurity measures. A spokesperson stated that “a very small number of systems were impacted” and are currently being restored. This incident, however, intensifies scrutiny on Microsoft’s security practices, particularly following a 2024 U.S. government report that called for urgent reforms in the company’s security culture.

Microsoft has identified the China-linked groups Linen Typhoon, Violet Typhoon, and Storm-2603 as being responsible for exploiting the critical SharePoint vulnerabilities. China’s embassy in Washington has vehemently denied the allegations, asserting its firm opposition to all forms of cyberattacks and criticizing “smearing others without solid evidence.”

In response to the widespread breaches, Microsoft has released emergency security patches for all affected SharePoint Server versions and urged immediate installation by all on-premises SharePoint users. The company also provided additional mandatory mitigation steps, emphasizing the high severity rating of the exploited vulnerabilities. This incident underscores the persistent and evolving threat of nation-state-sponsored cyberattacks against critical infrastructure and highlights the continuous need for vigilance and robust cybersecurity defenses.