Krebs points to a superb, long, detailed, in-depth analysis at the CitizenLab website: China’s Great Cannon.
We show that, while the attack infrastructure is co-located with the Great Firewall, the attack was carried out by a separate offensive system, with different capabilities and design, that we term the “Great Cannon.” The Great Cannon is not simply an extension of the Great Firewall, but a distinct attack tool that hijacks traffic to (or presumably from) individual IP addresses, and can arbitrarily replace unencrypted content as a man-in-the-middle.
The operational deployment of the Great Cannon represents a significant escalation in state-level information control: the normalization of widespread use of an attack tool to enforce censorship by weaponizing users. Specifically, the Cannon manipulates the traffic of “bystander” systems outside China, silently programming their browsers to create a massive DDoS attack. While employed for a highly visible attack in this case, the Great Cannon clearly has the capability for use in a manner similar to the NSA’s QUANTUM system, affording China the opportunity to deliver exploits targeting any foreign computer that communicates with any China-based website not fully utilizing HTTPS.
There's lots to dig into here. Thanks, CitizenLab, for sharing what you've learned.