Hong Kong's security chief yesterday said police had checked the city's central hub for internet traffic after whistle-blower Edward Snowden had revealed that it was a target for cyberspying by a US intelligence agency.
Secretary for Security Lai Tung-kwok, who appeared in Legco to answer lawmakers' questions on the matter, assured them the government had set up round-the-clock monitoring of the Hong Kong Internet Exchange (HKIX) at Chinese University.
The security chief was trying to placate a worried public following Snowden's claims in the media that US agencies have carried out hundreds of cyberspying operations in Hong Kong.
Meanwhile, security experts on the mainland said that hacking by US government organisations like the National Security Agency was almost impossible to defend against or detect.
A leading expert in Shanghai said the tools and methods used by these organisations were much different from those used by individual hackers. He and other experts suspect that the US agents use a secret "back door" installed in the main router chips or other hardware to carry out electronic intrusions.
A back door is an additional, undocumented feature deliberately built into a chip or device. They are mostly used by the chipmaker for legitimate maintenance but also allow those with the key to secure illegal local or remote access to a computer or network.
The experts said if Snowden's claims were proved to be true, the information he had would be "very valuable" to Beijing as it could be analysed to identify possible weak links in the networks.
"If Snowden is telling the truth... I am more than 90 per cent certain that the US government obtained secret access to the back door from US hardware manufacturers," said the expert, who refused to be named.
"Backbone networks are heavily guarded by firewalls and well-trained experts. Only those who can enter from the back door can carry out such continuous and extensive surveillance without alerting anyone."
This is not the first time China and the US face claims of spying on each other through "back doors". Last year, Cambridge researcher Sergei Skorobogatov published a report claiming that computer chips made in China and used in US military systems contained hidden back doors that could be used remotely to shut down fighter jets and nuclear power plants.
In Hong Kong, Lai said the government would not disclose any details of steps it had taken or would take to improve the city's cybersecurity. Asked if the government would offer protection to Snowden, who is believed to be in the city, he said: "Any person who considers his life to be at risk could seek help from the police."
IT sector lawmaker Charles Mok yesterday urged the government to relaunch an interdepartmental working group on technology crimes to ensure its network security was up to date.
Five pan-democratic lawmakers also demanded Legco's security panel hold a special meeting on cybersecurity and the surveillance laws.