BEIJING (CHINA DAILY/ASIA NEWS NETWORK) - Several media outlets have in recent days reported about the existence of a secret online industry that can virtually cause harm to anybody for a price.

For a few thousand yuan, these enterprises holding sway over a large number of users' accounts on social networking sites can make life hell for someone by spreading rumours about them, tampering with their photos or videos to show them in poor light, and making these orchestrated character attacks go viral.

The police have cracked down on some of these tormentors, but many more continue to harass unsuspecting people.

Such an industry forms part of the dark underbelly of the internet. Tampering with people's photographs and videos online violates their rights. Spreading rumours about them harms their reputation and making unwanted calls is harassment.

And damage to someone's reputation could leave a person scarred for life. The longer such an illegal industry exists, the more people will fall victims to it.

The existence of such an industry turns the internet into a hostile place, rather than a place where people can redress their grievances.

For years, people suffering some kind of injustice have turned to the internet, sharing their experience on social networking sites and channelising public opinion to fight for justice.

Many aggrieved parties have found solutions online.

In June, after it emerged that some people failed to get admitted to college, despite having cleared the college entrance exam, because some people "stole" their IDs to send their wards to college, society erupted as one, forcing the wrongdoers to be punished.

But the secret industry can sway public opinion and misuse the scope of the internet, even closing the channels for seeking justice.

The authorities must crack down on such illegal industries for the common good.

The writer is a columnist with the paper. China Daily is a member of The Straits Times media partner Asia News Network, an alliance of 24 news media organisations.