Great Cannon


The Great Cannon of China is an Internet attack tool that is used to launch distributed denial-of-service attacks on websites by performing a man-in-the-middle attack on large amounts of web traffic and injecting code which causes the end-user's web browsers to flood traffic to targeted websites. According to the researchers at the Citizen Lab, the International Computer Science Institute, and Princeton University's Center for Information Technology Policy, who coined the term, the Great Cannon hijacks foreign web traffic intended for Chinese websites and re-purposes them to flood targeted web servers with enormous amounts of traffic in an attempt to disrupt their operations. While it is co-located with the Great Firewall, the Great Cannon is "a separate offensive system, with different capabilities and design."
Besides launching denial-of-service attacks, the tool is also capable of monitoring web traffic and distributing malware in targeted attacks in ways that are similar to the Quantum Insert system used by the U.S. National Security Agency.

Mechanism

The Great Cannon hijacks insecure traffic inbound to servers within the Great Firewall, and injects JavaScript that redirects that traffic to the target. These attacks fail when websites have HTTPS encryption.

Known uses

The first known targets of the Great Cannon were websites hosting censorship-evading tools, including GitHub, a web-based code hosting service, and GreatFire, a service monitoring blocked websites in China.
In 2017, the Great Cannon was used to attack the Mingjing News website.
, the Great Cannon was being used to attempt to take down the Hong Kong-based LIHKG online forum.