New Delhi, Oct 30 : Mobile apps asking for access to location may be leaking your significant private information, including your activity, environment, and even the layout of the room or floor you are in, according to an alarming study by researchers at the Indian Institute of Technology (IIT) Delhi on Thursday.

The study, published in the journal ACM Transactions on Sensor Networks, focussed on AndroCon -- the first system to demonstrate that the 'fine-grained' GPS data already accessible to Android apps with precise location permissions can act as a covert sensor.

Without using the camera, microphone, or motion sensors, AndroCon was found to interpret nine low-level GPS parameters -- such as the Doppler shift, signal power, and multipath interference -- to infer whether someone is sitting, standing, lying down, inside a metro, on a flight, in a park, or in a crowded outdoor space. They could also infer if the room is crowded or empty, said researchers led by Soham Nag, M. Tech. Student at the Centre of Excellence in Cyber Systems and Information Assurance, IIT Delhi.

To turn the noisy raw data into clear insights, the team combined classical signal processing with modern machine learning.

'Across a year-long study spanning 40,000 sq. km and a lot of different phones, AndroCon achieved up to 99 per cent accuracy in detecting surroundings and over 87 per cent accuracy in recognising human activities -- even subtle ones like hand-waving near the phone,' said Prof. Smruti R. Sarangi, Computer Science and Engineering Dept., IIT Delhi.

The same framework can also sketch indoor floor maps -- identify rooms, staircases, and elevators -- with a margin of error under 4 metres, using only GPS patterns and user trajectories.

While AndroCon opens exciting possibilities for context-aware, privacy-respecting smart services, it also exposes a critical security gap. Any Android app with precise location permissions could potentially infer sensitive contextual information without explicit user consent, the team said.

'This study reveals an unseen side of GPS: a powerful but silent channel that can sense the world around us. AndroCon turns the everyday smartphone into an unexpectedly precise scientific instrument -- and a reminder that even the most familiar technologies still hold hidden secrets that can be misused by malicious entities,' Sarangi added.

/IANS