The Wall Street Journal suggests that Snowden gave China an incredibly powerful cyber weapon

The Wall Street Journal thinks Edward Snowden may have incidentally provided China with a new, powerful cyberweapon.

China is known for its "Great Firewall," a nationwide system of web blocks and filters that the government uses to maintain strict online censorship in mainland China.

Now it reportedly has a complementary offensive tool - dubbed the Great Cannon - to go after sites it doesn't like. And Snowden may be to blame.

"The Great Cannon is not simply an extension of the Great Firewall," experts at the University of Toronto's Citizen Lab reported, "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."

China can now re-route innocent traffic coming to Chinese websites and use it for a malicious distributed denial of service (DDoS) attack to overload the servers of another website. It may also be able to inject malicious code into target computers.

Citizen's Lab notes that the only other "known instances of governments tampering with unencrypted Internet traffic to control information or launch attacks" involve the use of a program called QUANTUM that was developed by the US's National Security Agency (NSA) and the UK's Government Communications Headquarters (GCHQ).

Snowden revealed the existence of QUANTUM through slides given to American journalists Glenn Greenwald and Laura Poitras in Hong Kong after he arrived on May 20 2013. The Journal is now wondering if the former NSA contractor provided the source code to Beijing before flying to Moscow on June 23.

"Did Snowden give the Chinese the code for the Great Cannon?" The editorial asks. "He denies sharing anything with foreign governments. But then he's an admitted liar, and we don't know what the Chinese and Russian spy services have been able to copy from what he stole."

The Journal's evidence regarding Snowden and the Great Cannon is scant and circumstantial and is mainly based on suspicion of Snowden, the similarities between the Great Cannon and QUANTUM, and timing.

"A South China Morning Post report that the Great Cannon has been under development for about a year is suggestive," the Journal asserts. "This means China's hacking bureaucracy geared up to produce this new product soon after the Snowden leaks."

In any case, China now has a powerful new cyberweapon to enforce its the world's vastest internet censorship regime.

"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," CitizenLab notes.