Pegasus spyware is back in the news. After making waves in India in 2019 -- when some WhatsApp users received messages from WhatsApp telling them that Pegasus had compromised their phones -- several media organisations published detailed lists of people targeted once again by the spyware.

A number of prominent news websites, including the Guardian and the Washington Post, published details of what they called global surveillance operations using Pegasus. The spyware reportedly targeted journalists, including over 40 journalists in India, activists and other key public figures. Reports also suggested that two ministers and a judge may also have been targeted.

Also read: Government of India denies Pegasus row, say no unauthorised interceptions

The reports added that over 10 governments, including India, are involved in surveillance of people using Pegasus spyware. Meanwhile, the Indian government has issued an official statement categorically denying the allegations saying "the commitment to free speech as a fundamental right is the cornerstone of India's democratic system. We have always strived to attain an informed citizenry with an emphasis on a culture of open dialogue.

Also read: Six steps to secure your online transactions, bank details

Pegasus is a spyware developed by an Israeli company, NSO Group. Experts say that the firm specialises in cyber weapons. It first made headlines 2016, when an Arab activist got suspicious after receiving a shady message. Since then, Pegasus has been in news off and on as newer versions have been detected.

Here's how Pegasus works

Pegasus spyware is one of the most sophisticated equipment in the world. The hacking is so smooth that phone users have no clue that their devices have been compromised.

* Once hackers identify a target, they send the targeted user a malicious website link, and if the user clicks on it, Pegasus is installed on the phone.

* It can also be installed through a security bug in voice calls made through apps suc as WhatsApp.

*Such is the level of sophistication that Pegasus can be installed on the targeted phone just by giving a missed call to the user.

* Once the software is installed it deletes the call log entry so that the user doesn;t know about the missed call.

* One installed, Pegasus can potentially spy on the targeted user 24X7.

*Even encrypted chats, like the ones made through WhatsApp, are not safe.

* Experts say Pegasus can track calls, track user activity within apps, gather location data, access video cameras in a phone, listen through their microphones and read messages

* At the same time, Pegasus can avoid being detected

What does it cost

Most spyware apps, of the standard of Pegasus, are extremely expensive. The cost is in millions of dollars, which can only be paid by big organisations or governments.