# A ZDNET tester lists five USB cables and dongles that can steal data or damage a Mac > A ZDNET tester’s hacking cable captured a friend’s login by accident. How keystroke-injecting cables and other hostile USB hardware work, and what a Mac firewall can’t do about them. HisnLabs Security & Research Team (HisnLabs) · Published 2026-09-26 Canonical: https://hisnlabs.com/en/news/usb-cables-dongles-steal-data-omg-cable Adrian Kingsley-Hughes, a senior contributing editor at ZDNET, once lent a friend what he thought was an ordinary cable. Later that day he got a notification: the cable had captured the login credentials of the computer it was plugged into and sent them to him. It was one of his O.MG test cables, mixed up with the normal ones. He [told the story this week](https://www.zdnet.com/tech/most-dangerous-tech-cables-dongles-explained/) in a round-up of cables and dongles that can damage hardware or steal data. ## Background A USB connector carries both power and data over the same physical plug, and the device on the other end decides what it does with each. That is what makes ordinary-looking USB hardware capable of more than charging: a cable or dongle can contain its own processor, memory and radio, all invisible from the outside. ## Findings - USB-A to USB-A cables. USB-A was designed as the end that supplies power, so connecting two hosts can do anything from nothing at all to sparks and smoke. They exist for niche jobs such as KVM switches and flashing firmware [[1]](https://www.zdnet.com/tech/most-dangerous-tech-cables-dongles-explained/). - “Medusa” multi-head charging cables. Good ones shut down safely if power is connected the wrong way; Kingsley-Hughes has seen plenty of cheap ones simply die [[1]](https://www.zdnet.com/tech/most-dangerous-tech-cables-dongles-explained/). - The O.MG cable. It looks and behaves like a normal cable but hides a microprocessor and a Wi-Fi chip, so it can inject keystrokes, run scripts and log keys. Some can wipe their payload or self-destruct if discovered [[1]](https://www.zdnet.com/tech/most-dangerous-tech-cables-dongles-explained/). - USBKill dongles. Built to damage the device they are plugged into with a high-voltage discharge, triggered on insertion, by an app, on a schedule, by radio or with a magnetic ring. Kingsley-Hughes says newer hardware resists better than pre-USB-C hardware, but plenty still fails [[1]](https://www.zdnet.com/tech/most-dangerous-tech-cables-dongles-explained/). - Fake data blockers. A real data blocker passes power but not data, and he carries one when charging from ports he doesn’t control. Some look-alikes carry payloads of their own instead [[1]](https://www.zdnet.com/tech/most-dangerous-tech-cables-dongles-explained/). The article also covers “widowmaker” male-to-male mains extension cords, which can kill; the US Consumer Product Safety Commission has secured commitments from large marketplaces to delist them. Kingsley-Hughes’s own rules: don’t plug random cables or dongles into your devices, use a data blocker when travelling, and never use a widowmaker cord [[1]](https://www.zdnet.com/tech/most-dangerous-tech-cables-dongles-explained/). > FireAI treats any app launched from a USB stick or external disk as a stranger: it has to ask before it goes online. Try it free for 17 days. [Download FireAI for Mac](https://hisnlabs.com/fireai/en/download) ## Implications for Mac users A cable like the O.MG works by pretending to be a keyboard. Whatever it types, the Mac treats as if a person typed it. No firewall can tell those keystrokes from a user’s own, and FireAI doesn’t claim to. Two things do help against this specific part: on Mac laptops with Apple silicon, macOS can ask before a new USB accessory is allowed to connect (System Settings › Privacy & Security › Allow accessories to connect; “Ask for new accessories” or stricter), and the Keyboard Setup Assistant that appears when an unknown “keyboard” is plugged in is a warning sign if the user didn’t plug in a keyboard. A cable with its own Wi-Fi chip can also send what it captures without touching the Mac’s network at all, a channel no Mac firewall can see. ## Recommendations 1. Don’t plug unfamiliar cables or dongles into your devices, including ones borrowed from someone else. 2. Use a genuine data blocker when charging from a port you don’t control, such as a public USB port; check it against a known-good source rather than trusting the look of it. 3. Never use a “widowmaker” male-to-male mains extension cord. 4. If the Keyboard Setup Assistant appears after plugging in something that isn’t a keyboard, close it and unplug the device immediately. 5. Set macOS to ask before new USB accessories connect: System Settings › Privacy & Security › Allow accessories to connect. ## Relevance to FireAI Where FireAI does have a role is what happens after a cable delivers its payload. Keystrokes are often used to fetch and start a program, and that program then has to talk to the internet from the Mac. FireAI asks the first time any app wants to connect, shows every destination on the world map, and has a kill switch that refuses new connections in one click. The other common USB trick is simpler: a stick or drive with a program on it that someone runs. [USB Network Protection](https://hisnlabs.com/fireai/en/docs/usb-network-protection) is built for that case: an app launched from an external or removable drive never gets online silently, and in Paranoid and Under attack modes it is denied outright unless it has an explicit Allow rule. It does not, and cannot, stop a cable that types or a dongle that sends a power surge; those need the physical habits above. > Software launched from a USB drive can’t phone home silently on a Mac running FireAI. Try it free for 17 days. [Download FireAI for Mac](https://hisnlabs.com/fireai/en/download) ## Limitations ZDNET’s report is based on one tester’s own experience and hands-on testing of specific products, not an independent lab study, and it does not estimate how common malicious cables and dongles are in everyday use versus their use as red-team or research tools. The article does not name specific fake-data-blocker products, so it is not possible to check a purchase against its findings directly. For more on how these attacks play out, see our guide to [the USB drop attack](https://hisnlabs.com/en/blog/usb-drop-attack-mac). [Download FireAI](https://hisnlabs.com/fireai/en/download) and try it free for 17 days. FireAI is made by HisnLabs. ## Sources - [ZDNET (Adrian Kingsley-Hughes), 23 September 2026: Five USB cables and dongles that can fry your hardware, steal your data, or worse](https://www.zdnet.com/tech/most-dangerous-tech-cables-dongles-explained/)