By cross-referencing just one hour of footage from public webcams with stories taken in Times Square, BuzzFeed News confirmed the full identities of a half dozen people.

Ben Kothe / BuzzFeed News

When you create and post an Instagram story in a public space you may be inadvertently giving away far more information about yourself and your movements than you realize. As ubiquitous surveillance intersects with social media data trails, it has become incredibly easy to identify individuals in public places. By cross-referencing just one hour of video footage from public webcams with Instagram stories taken and shared in Times Square, BuzzFeed News was able to confirm the real names and identities of a half dozen people. Modern cities are filled with thousands of cameras, many of them constantly collecting images of people in public spaces. And although some cities have moved to limit the use of facial recognition in policing, almost no restrictions exist on the far more common use of public-facing surveillance cameras, which are capable of capturing individuals and their movements across cities for law enforcement, corporations, and even members of the general public. In the US, there are no laws governing how long companies or individuals can keep these images or what they can be used for. (BuzzFeed News did not use any facial recognition software to identify people in Times Square.) While there have long been CCTV cameras trained on the public, there has been an explosion in recent years. Unofficial estimates put the number of cameras in London, reportedly the most surveilled city outside of China, at one camera for every 14 people. Meanwhile, the rise of social media has meant billions of people are now posting photos of themselves online, often publicly. Every day, more than 500 million people around the world share photos or videos on Instagram alone. This means that publicly available webcams in high-traffic public places make it easy to locate Instagram users in the footage, by tracking stories posted from the same location using geotags and hashtags. Although this is possible with a variety of apps with location tagging, Instagram is an especially effective means of identification given that it is public by default — it takes multiple steps within the app’s settings to set your account to private — and also has a massive user base of more than 1 billion accounts. The fact that Instagram features rich content of images and videos, as opposed to a text-only tweet or a Facebook update, for example, also make a huge difference because viewers can work out the precise location a user is standing in when they captured a snippet of footage. In many of the cases, we found personal details including occupations, addresses, phone numbers, and contacts just by searching social media. It took just minutes searching on Google to find even more detailed information about individuals. To protect the users' privacy, we are not revealing their identities here, and we have deleted the data we collected about them. This level of detail underscores just how much information people are unwittingly revealing in videos, both the ones posted on social media and those taken of people in public spaces. This kind of information can be and is used by groups ranging from intelligence services to advertisers to build profiles of individuals. For example, authorities could use publicly available webcams filming an area where a protest is taking place. By looking at Instagram stories that protesters post in real time at any particular location, authorities would be able to identify them and track their movements throughout a city using other cameras, including before they arrived at the protest, and what they did afterwards. Other people featured in the background of the Instagram posts could also be identified — by facial recognition technology, for example — and followed in this way. In our experiment identifying people using their Instagram stories, we started with camera footage from tourism and surveillance company EarthCam, which streams live footage online for free and also makes previous days’ footage available for anyone to access. EarthCam is among a handful of companies that place cameras in highly trafficked areas — from tourist hotspots like Times Square and Andy Warhol’s grave to university campuses. Then we synced and compared the streaming footage EarthCam posts online to Instagram stories geotagged to Times Square. To show you how we did it, BuzzFeed News’ Hayes Brown acted as a guinea pig for demonstration purposes. We sent Hayes to Times Square, where he wandered around and posted Instagram stories of street performers, chain restaurants, and himself. Hayes recorded tourists sitting on stairs sweltering in the August heat, a street performer dressed in a full-body Pikachu costume, and New York’s “beloved” Naked Cowboy strumming a guitar as a tourist bus drives past.

Hayes Brown / BuzzFeed News Hayes' Instagram stories in Times Square

Meanwhile, we recorded about an hour of footage from EarthCam’s cameras, which are mounted around Times Square.

EarthCam A clip of selected footage from the Times Square EarthCam.

Then we searched for Instagram stories posted at the same time and recorded those too. We could figure out exactly where Hayes was standing in Times Square based on who and what appeared in his Instagram stories. While this experiment was staged, the process for identifying him and tracking his movements was identical to the way we identified the half dozen private individuals. Once we identified Hayes in the video footage, we could map exactly where he moved throughout Times Square and observe what he did, even if he didn’t share it online. For example, Hayes took a selfie with the Naked Cowboy, but he never posted it. But we know he took the photo from monitoring EarthCam’s footage. If we had continued the experiment outside Times Square, it would have been just as easy to chart his course through other parts of the city too, so long as we had access to other publicly available footage, including New York’s traffic cameras. Many of the Instagram stories we looked at before replicating the exercise with Hayes were shots of people milling around Times Square, including tourists, performers, and people who worked at businesses in the area. While it's a user’s choice to post an Instagram story, other people can also be caught in the background and subsequently be tracked. “As a matter of principle, we think people should decide for themselves if they want to share publicly or privately. Much like any photo posted publicly to the internet, there’s a risk others will use it without permission, in unintended ways. It’s a leap to suggest Instagram should privatize the behaviors of people who choose to share their content with the world,” Instagram told BuzzFeed News. Lisa Kelly, executive director at EarthCam, said, “Everybody is walking around with a camera phone these days,” and noted that some EarthCam cameras had signs that read “Smile! You’re on EarthCam” near them. “Is it showing people who are maybe unaware? Possibly. But we’re also in a time where everyone has cameras and anybody can end up anywhere,” she added.

Zachary Ares / BuzzFeed News; EarthCam Tracking Hayes' movements through Times Square based on his Instagram activity.