Unveiling Wireless Users' Locations via Modulation Classification-based Passive Attack

TL;DR

This paper introduces a passive wireless user localization attack leveraging modulation classification, exploiting standard protocol information to accurately determine user positions without active probing.

Contribution

It presents a novel two-phase passive attack method that combines modulation classification and strategic channel sniffing to localize wireless users.

Findings

Effective localization within a reduced search space

Utilizes publicly available MCS tables for pseudo-ranging

Potential extension to non-line-of-sight scenarios

Abstract

The broadcast nature of the wireless medium and openness of wireless standards, e.g., 3GPP releases 16-20, invite adversaries to launch various active and passive attacks on cellular and other wireless networks. This work identifies one such loose end of wireless standards and presents a novel passive attack method enabling an eavesdropper (Eve) to localize a line of sight wireless user (Bob) who is communicating with a base station or WiFi access point (Alice). The proposed attack involves two phases. In the first phase, Eve performs modulation classification by intercepting the downlink channel between Alice and Bob. This enables Eve to utilize the publicly available modulation and coding scheme (MCS) tables to do pesudo-ranging, i.e., the Eve determines the ring within which Bob is located, which drastically reduces the search space. In the second phase, Eve sniffs the uplink channel, and employs multiple strategies to further refine Bob's location within the ring. Towards the end, we present our thoughts on how this attack can be extended to non-line-of-sight scenarios, and how this attack could act as a scaffolding to construct a malicious digital twin map.