SmartAttack: How Smartwatches Can Hack Air-Gapped Security Systems

For decades, the fortress-like defense of air-gapped computers—those completely disconnected from external networks—has stood as a cornerstone of security in top-secret governmental agencies, defense contractors, and industries with critical infrastructure. The guiding philosophy was simple: if a device cannot communicate, its secrets cannot be smuggled out. Yet, as technology advances and the pervasiveness of connected wearables explodes, researchers are constantly probing the walls for cracks. The latest research out of Ben-Gurion University of the Negev in Israel—the so-called SmartAttack—shows that even these digital fortresses are not immune to subtle, high-tech threats lurking on employees’ wrists. This emerging, critical research highlights the unpredictable ways in which smartwatches could enable data exfiltration from air-gapped machines using nothing but ultrasonic soundwaves and innocuous apps. Here’s how SmartAttack works, what it means for high-security environments, and the big-picture lessons for anyone banking on the illusion of perfect isolation.

The Myth of Air-Gap Security​

Air-gapping—a security strategy in which sensitive computers never touch an external network—has, for years, played the role of “final defense.” The rationale is straightforward: a computer physically isolated from the internet cannot be hacked remotely, and hackers have no common route to sneak data off such a machine. This idea, however, is not bulletproof.
History is littered with examples demonstrating that even air-gapped systems can be breached:

• Malicious insiders or careless contractors: Sometimes, a USB drive with malware is all it takes—Stuxnet, the worm that sabotaged Iranian nuclear centrifuges, used this very route.
• Supply chain attacks: Sophisticated adversaries have targeted the hardware or software provision process, infecting systems before they’re deployed in secure zones.
• Covert communication channels: Various side-channel attacks—ranging from electromagnetic emanations to subtle manipulations of speakers and fans—have been explored by cyber researchers.

Yet, the most daunting phase of any attack on air-gapped systems is not merely infiltration (getting a foothold), but exfiltration: actually sending the pilfered data from the island back to the attacker. Conventional wisdom suggests that no radios, no networks, and strong access controls are enough. But in the cat-and-mouse game of cybersecurity, creative thinking is a potent weapon.

SmartAttack: How a Smartwatch Transforms Into a Data Ferry​

The SmartAttack research team, led by Mordechai Guri—head of the Offensive Cyber Research Lab at Ben-Gurion University—has built a compelling proof-of-concept showing how air-gapped data can be surreptitiously ferried offsite using the humble smartwatch. Here’s the progression of this sophisticated attack:

1. The Initial Compromise​

To execute SmartAttack, the attacker must first infect the air-gapped computer with highly specialized malware. This first step is non-trivial—a feat typically requiring a malicious insider, a successful supply-chain attack, or a second compromised device (like a USB key). However, as history shows, such penetration is far from impossible and has been achieved in the wild by nation-state actors.

2. Covert Ultrasonic Transmission​

Once the malware lodges itself on the target machine, it modulates sensitive data—anything from cryptographic keys to confidential documents—into an ultrasonic signal, in the frequency range 18–22 kHz. This sound is intentionally chosen because it’s above the threshold of human hearing, meaning it can operate unnoticed in normal working environments.
Modern computers’ speakers can, perhaps surprisingly, emit these ultrasonic soundwaves, and smartwatches—with their increasingly powerful microphones—can detect them. Guri notes, “Our approach utilizes the built-in microphones of smartwatches to capture covert signals in real time within the ultrasonic frequency range of 18–22 kHz.” This turns every smartwatch in the vicinity (potentially any employee’s wearable) into a potential eavesdropping device.

3. Handoff Via the Watch​

The next step is elegantly simple: once the smartwatch microphone (perhaps running a malicious audio-monitoring app) picks up these ultrasonic signals, it decodes the data in real time. The attacker doesn’t even need to physically access the smartwatch. The malware on the watch can then relay the stolen data—using the device’s own Wi-Fi, cellular connectivity, or even paired Bluetooth—to a remote server controlled by the attacker.
What’s particularly insidious is that this does not require the attacker's own smartwatch; any compromised employee’s wearable could suffice. Traditional network-based security measures are thus bypassed entirely. According to Guri, “The smartwatch then forwards the extracted data to the attacker using available communication channels such as Wi-Fi, cellular networks, or Bluetooth tethering... effectively bypassing traditional security measures.”

4. The Wider Implications​

The key insight here is not simply that this specific method works, but that the entire family of audio-capable wearables—smartwatches, smart earbuds, and beyond—represent latent vulnerabilities in secure environments. SmartAttack’s findings, in Guri’s words, “highlight the security risks posed by smartwatches in high-security environments.”

A Deep Dive Into the Technology​

To appreciate both the promise and peril of SmartAttack, let’s examine the underlying technology and its prerequisites:

Malware Transmission via Sound​

Encoding binary data into sound waves is not new; modems operated this way for decades, and researchers have long used audible and inaudible frequencies for data-over-audio experiments. The advance in SmartAttack is its stealth and practical use in a real-world (if extreme) scenario.

Technical Prerequisites​

• A compromised host: The air-gapped computer needs the malware installed—a significant, though not unprecedented, hurdle.
• Speakers functional and unmuted: Many secure installations physically disable speakers, but not all.
• A nearby smartwatch with an open microphone: The wearable must have a malicious app that listens for signals, a factor that is not always obvious to most end users.

Data Rates and Practicality​

SmartAttack’s prototype achieves a data transmission rate of roughly 10–20 bits per second, at distances up to several meters in a quiet room. This may sound sluggish, but it’s fast enough to exfiltrate encryption keys or other high-value secrets in seconds. For reference, a 256-bit AES key—enough to decrypt a proprietary database or confidential disk—can be whisked away in under 30 seconds.
These limitations also, in some ways, protect against high-volume data thefts (like gigabytes of files), but underscore the realistic risk posed by the exfiltration of “crown jewel” credentials.

Limitations and Detection​

Sophisticated attackers could, in theory, mask these ultrasonic transmissions amid legitimate system sounds or schedule them for times when ambient noise is lowest. Countermeasures—such as spectrum analysis or continuous monitoring of the ultrasonic range—are rare and costly, particularly when compared to the widespread deployment of wearables themselves.

The Expanding Attack Surface of Wearables​

While much of the public focus about data security has traditionally centered on smartphones and laptops, wearables represent an explosive new vector. Industry estimates project that by 2025, over 600 million smartwatches will be in regular use globally, with enterprise wearables (for productivity, health, and messaging) representing a fast-growing segment.
Smartwatches possess several attributes that make them ideal for covert roles in data exfiltration:

• Constant connectivity: Most models support Wi-Fi and LTE, enabling independent communication.
• Integrated microphones and sensors: Designed for voice commands, yet vulnerable to misuse.
• App ecosystems: Even sanctioned enterprise environments may lack granular controls over what apps are installed, what permissions they grant, and how (or if) audio sensors are monitored.

In secure environments, smartphones have long been banned or heavily restricted. But the infiltration of wearables—smaller, often considered less “threatening”—has outpaced policy and technical controls. SmartAttack is, in essence, a warning that the lag between technological advancement and enterprise risk management may be shrinking at an uncomfortable rate.

Risk Assessment: How Plausible Is SmartAttack in the Real World?​

Notable Strengths​

• Novelty and stealth: The average security posture in high-security environments is not tuned to suspect or block ultrasonic sound-based exfiltration.
• Leveraging existing tech: No exotic hardware or firmware hacks are required—just common speakers, mics, and off-the-shelf wearables.
• Bypassing network-based defenses: Since the transfer happens via sound and then over the cellular/Wi-Fi link of the smartwatch, firewalls and data loss prevention solutions are ineffective.

Potential Risks and Barriers​

While the attack’s ingenuity is unquestionable, several caveats apply, tempering fears of rampant abuse:

• Initial malware installation is non-trivial: Infiltrating an air-gapped environment still ranks among the hardest tasks; only sophisticated, well-resourced attackers are likely to attempt this.
• Physical requirements: The smartwatch must be in the target area and running the required app. Stringent physical security monitoring can mitigate this risk.
• Volume limitations: Large-scale data theft—like GBs of files—is infeasible; SmartAttack is best suited for highly targeted thefts (keys, passwords, device configurations).

Nevertheless, all these limitations must be weighed against the value of the potential target: nuclear command codes, proprietary algorithms, or government troves, for instance, are absolutely worth the effort of sophisticated adversaries.

Critical Analysis and Recommendations​

The significance of SmartAttack lies not only in its proof-of-concept, but in the paradigm shift it represents for modern security thinking. Several important lessons can be drawn:

1. Perfect Isolation Is a Mirage​

Air-gapped systems are, by design, meant to be “untouchable.” Yet, every additional piece of technology—be it a laser printer, monitor, or, now, wearable—expands the risk surface. Policy and security design must address the totality of endpoints, not just traditional computing devices.

2. Prohibitions Must Keep Pace With Tech​

Most secure installations already ban smartphones. The SmartAttack research strongly suggests extending this ban to include all audio-capable wearables, including smartwatches, earbuds, and even certain smart badges or key fobs. Guri himself notes, “Restricting or prohibiting the use of smartwatches and similar audio-capable wearables in sensitive environments is a direct mitigation strategy.”
This approach, while effective, comes at a cost: convenience and employee morale. Some organizations will weigh this tradeoff differently, but those with the highest-stake secrets may find the argument compelling.

3. Layered, Not Single-Layer Defense​

Assuming that technical controls alone will secure vital data ignores the growing sophistication of attacks leveraging human-centered or ambient channels:

• Physical security: Restrict not only unauthorized personnel, but also unauthorized devices—every smartwatch, earbud, or sensor is a potential listening post.
• Application control policies: Strong endpoint controls are needed for all connected devices, including vetting of app permissions on corporate wearables.
• Environmental sound monitoring: Security cameras have become privacy-standard in high-value environments; perhaps the next step is real-time spectrum analysis for ultrasonic anomalies.

Emerging Countermeasures​

Addressing the SmartAttack family of threats will require a mix of technology, policy, and training.

Technological Solutions​

• Ultrasonic jamming: Simple ultrasound noise generators could scramble attempts to transmit data over the air. The downside: some ultrasonic transmissions are used for legitimate building or medical applications.
• Environmental monitoring: Installing spectrum analyzers or “digital guard dogs” can detect anomalies in the ultrasonic band, alerting security if transmissions cross thresholds.
• Firmware tampering detection: Trusted boot environments and heavy device attestation checks can make it far harder for malware to take root or survive unnoticed.

Policy Updates​

• Review and update device policies: Regularly revisiting what devices are allowed in secure areas is crucial—today’s “benign” wearable could be tomorrow’s threat.
• Employee training: Staff awareness campaigns should highlight not only obvious threats, like plugging in USB drives, but also the potential for “invisible” attacks using everyday tech.

Industry Collaboration​

Vendors must also play their part, ensuring smartwatches and other wearables build in strong permission models, tamper-proof microphones, and transparent ways for enterprises to manage or audit relevant device activity.

The Future: New Frontiers, New Threats​

The story of SmartAttack is not, primarily, one of panic, but of proactive adaptation. As the world races toward ubiquitous computing, the range of possible data exfiltration channels multiplies. Today it’s ultrasonic signaling; tomorrow it might be optical transmission via subtle LED patterns, electromagnetic radiation, or haptic (vibration-based) side channels.
And with advances in AI, attackers may soon be crafting malware that adapts its exfiltration strategy to the available environment—choosing between ultrasonic, infrared, or even magnetic approaches, depending on what sensors are available.

Conclusion​

SmartAttack, the brainchild of researchers at Ben-Gurion University, is a timely wake-up call: no environment is truly impervious if new connectivity is introduced—wittingly or unwittingly. For organizations entrusted with the world’s most sensitive information, the challenge is not only technical but cultural. Wearables, in their quest to help us, may incidentally help our adversaries too.
For professionals engineering the world’s highest-security environments, the lesson is clear: scrutinize every device, every channel, and every assumption about what can and cannot “talk.” In the contest between innovation and exploitation, vigilance is the only defense.
If your organization is responsible for protecting deeply sensitive assets, now’s the moment to look at the wrists—and rethink what “secure” really means in a world of invisible, unending connectivity.

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Source: Forbes Your Smartwatch Can Steal Highly Secure Data — Here’s How