Location data collected from smartphones and apps can pose a real security risk if it falls into the wrong hands.
Privacy expert Harto Pönkä says an individual can be identified even in a large set of supposedly anonymous location data by looking at places they are known to visit. Their movements can then reveal information such as their home address.
“In the worst case, this could expose a person to violence,” Pönkä told Verkkouutiset.
Particular caution is needed when someone’s address is meant to remain confidential. Measures intended to conceal a person’s address offer little protection if their smart devices and apps are continuously transmitting precise location information to outside parties around the world.
The risks can become especially serious for people who are being stalked or otherwise targeted by a hostile individual, such as a former partner or another harasser.
Pönkä also raises concerns about national security. He says people working even in moderately sensitive positions should avoid using devices or apps at their workplace if those services transmit their location to outside parties.
The issue has received renewed attention in Finland after Helsingin Sanomat reported obtaining a dataset containing location information from hundreds of thousands of Finns. The newspaper was able to link movement data to individual people and identify locations including their homes and workplaces. Politicians and military personnel were among those whose movements appeared in the data.
Pönkä says the findings did not surprise him. Similar investigations have been carried out elsewhere. He points to a 2019 New York Times investigation that demonstrated how the movements of US President Donald Trump could be traced using supposedly anonymous location data.
Privacy commissioner says there is no reason to panic
Finland’s Data Protection Ombudsman Anu Talus was likewise unsurprised by how precisely individuals could be identified from location information, although she takes a more measured view of the risks.
“There is no reason to panic about this,” Talus told Verkkouutiset.
According to Talus, the important point is to make clear what large-scale tracking actually means in practice. Apps have collected location data for years, but many users have had little understanding of how detailed that information can become.
She says people often assume that their identity cannot be determined because location information is collected anonymously. In reality, individuals can often be identified even when their names are absent from a dataset. Much depends on what information has been collected and how easily it can be combined with other data.
“People do not always realize how revealing a picture the collection of location and movement data can create of a person,” Talus says.
Users may not even know they are being tracked
Pönkä says another problem is that users do not always understand the extent of the permissions they have granted.
Some people accept permissions requested by websites and apps without examining exactly what they are agreeing to. But Pönkä says the responsibility does not lie with users alone. The way consent is requested can itself obscure what information is being collected.
Location tracking, for example, may be included in a website’s cookie consent settings without being immediately obvious.
“Consent is usually requested in a way that means the user does not even see that their location is also being tracked. This often happens when someone clicks ‘Accept all’ on a website’s cookie banner,” Pönkä says.
Users may have to open additional menus to see what information is being collected and which parties receive it. Even then, the details can be difficult to find.
Pönkä criticizes arrangements in which one click grants consent to a large number of partners and purposes. Information collected from a user does not necessarily remain with the service provider. It can be shared with dozens or even hundreds of other parties and may also be sold onward.
That means the possibility of data eventually reaching hostile or criminal actors cannot be completely ruled out.
“The data business is precisely about this: when you give permission to one party, the information ends up with countless others for their own purposes,” Pönkä says.
Turning off GPS is not enough
Limiting location tracking does not simply mean switching off GPS. A phone or other device can also reveal its location through other technologies.
“Location can be determined, for example, by scanning the WLAN networks that are available,” Pönkä says.
He therefore recommends disabling Wi-Fi and Bluetooth connections when they are not needed.
Users should also check which apps have permission to access their location and remove unnecessary permissions. Pönkä advises rejecting unnecessary cookies, considering restrictions on Wi-Fi and Bluetooth scanning, and checking whether location history is stored in a Google or Apple account. Stored information should be deleted if there is no real need to keep it.
Talus notes that completely preventing all collection of location data may be difficult in today’s digital environment. Users can nevertheless limit how much information they disclose.
For every app, she recommends considering whether it genuinely needs continuous access to the user’s location. The same principle applies to other permissions, including access to a phone’s camera, microphone, contacts and stored files.