Information From Thin Air: Using SDR to Extract DTMF from Radio Waves
Summary
This article describes a technique using Software Defined Radio (SDR) to extract Dual-Tone Multi-Frequency (DTMF) signals from radio waves. It highlights the potential for eavesdropping on signals that might otherwise seem unintelligible, emphasizing the need for awareness of such possibilities.
IFF Assessment
The ability to extract potentially sensitive DTMF signals from radio waves without direct access to a device presents a new eavesdropping vector for attackers.
Defender Context
Defenders should be aware of the potential for radio-based exfiltration of signaling information, especially in environments where DTMF tones are used for control or authentication. This technique highlights the importance of considering the physical radio spectrum as a potential attack surface for information leakage.