The Great Cannon of China is an attack tool that is used to launch distributed denial-of-service attacks on websites by intercepting massive amounts of web traffic and redirecting them 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.
The first known targets of the Great Cannon (in late March 2015) were websites hosting censorship-evading tools, including GitHub, a web-based code hosting service, and GreatFire, a service monitoring blocked websites in China.
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