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The humble USB cable is part of an electrical revolution

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Re: The humble USB cable is part of an electrical revolution

#21

Post by jakobe »

kabdib wrote: post #3

It's going to be interesting, from a security standpoint. One of the original cracks on the PS3 was via the USB stack. I'd not go plugging my computers or phones into jacks that I don't necessarily control. I can see a market for buffering devices that allow power through, and perhaps do power negotiation for you, but that do not allow data traffic. I believe these devices already exist. though I don't know how sophi…

Even worse than USB is Firewire, which, if I am not mistaken, gives direct memory access to whatever device is connected.

However, manufacturers are already realising that blindly trusting every USB host is a bad idea. For example, iPhones now ask if you want to trust if you connect to a previously unknown computer via USB. If you chose not to, your iPhone will take power, but won't allow data access. Therefore it's no longer possible to create a device that looks like a charger but that actually downloads all the photos from your phone.

Re: The humble USB cable is part of an electrical revolution

#22

Post by nwh »

jakobe wrote: post #21
kabdib wrote: post #3

It's going to be interesting, from a security standpoint. One of the original cracks on the PS3 was via the USB stack. I'd not go plugging my computers or phones into jacks that I don't necessarily control. I can see a market for buffering devices that allow power through, and perhaps do power negotiation for you, but that do not allow data traffic. I believe these devices already exist. though I don't know how sophi…

Even worse than USB is Firewire, which, if I am not mistaken, gives direct memory access to whatever device is connected. However, manufacturers are already realising that blindly trusting every USB host is a bad idea. For example, iPhones now ask if you want to trust if you connect to a previously unknown computer via USB. If you chose not to, your iPhone will take power, but won't allow data access. Therefore it's…

> Even worse than USB is Firewire, which, if I am not mistaken, gives direct memory access to whatever device is connected.

Both FireWire and Thunderbolt offer DMA. There's publicly available tools that allow you to extract passwords, remove lock screens and find keys in the memory of running devices using either type of port.

Re: The humble USB cable is part of an electrical revolution

#23

Post by xlayn »

kabdib wrote: post #3

It's going to be interesting, from a security standpoint. One of the original cracks on the PS3 was via the USB stack. I'd not go plugging my computers or phones into jacks that I don't necessarily control. I can see a market for buffering devices that allow power through, and perhaps do power negotiation for you, but that do not allow data traffic. I believe these devices already exist. though I don't know how sophi…

or you can just cut the two data cables or put a piece of tape on the two data connectors on a usb2 cable.... pleaaaase and it's almost free...

Re: The humble USB cable is part of an electrical revolution

#24

Post by _Adam »

If anyone is interested in the actual technical details, check out the docs here: http://www.usb.org/developers/docs/

There's a 37.7MB zip and the USB PD specification (328 pages) is packaged within.

In order to ensure shit doesn't melt, they'll have detectable cables for >5V and >1.5A operation. I'm reading the spec to find out how they plan to do cable detection. IC based, or electrical connections, or maybe something else?

Re: The humble USB cable is part of an electrical revolution

#25

Post by nickff »

x0x0 wrote: post #5
kabdib wrote: post #3

It's going to be interesting, from a security standpoint. One of the original cracks on the PS3 was via the USB stack. I'd not go plugging my computers or phones into jacks that I don't necessarily control. I can see a market for buffering devices that allow power through, and perhaps do power negotiation for you, but that do not allow data traffic. I believe these devices already exist. though I don't know how sophi…

(I'm not an engineer). I a similar article; iirc android phones could be owned by plugging them into a hostile usb connection. I wonder, though, if you couldn't produce a simple adapter that just drops some of the pins? Maybe I don't know enough about usb.

Speaking as someone who writes embedded software using USB stacks for a living, there are a number of solutions to this. Your solution is possible, and is how many iPhone USB charging cables are designed. If limited communication is required, the device being charged can also contain a separate processor for the interface. The ideal solution is for the device to contain some security measures, to prevent these issues; this solution is also the least versatile or most costly depending on implementation, and may not be achievable.

Re: The humble USB cable is part of an electrical revolution

#26

Post by jzwinck »

This is great. Five years ago I carried on trips a phone with a proprietary USB cable, a GPS with mini-USB, a pocket camera with a like-sized charger (and 2m lead, which I refactored), and a AA battery charger for the rest of the stuff.

These days, bike lights charge from mini-USB (or even have integrated USB A plugs), phones are semi-required to use micro-USB, computer mice have USB charging and data, and I recently learned that even pocket UV water treatment devices use micro-USB and integrated Li-ion instead of AAs now. I think the only use I have for AA batteries anymore is a camera flash. One of the requirements when I bought a pocket camera recently was that it charge via USB (Sony gets this; Olympus sort of does but their cables are "special"; Canon has one or two models).

USB power can also do wonders for places where mains power is provided only part of the day. Those USB "power banks" are already taking off, and the more things we can use them with, the better.

We've basically killed off the C and D-size battery, the 6V lantern, and a bunch of other unnecessary form factors. Now let's finish the job--we can make AAAs as obscure as AAAAs if we get USB charging remote controls, and there's no reason we can't make smoke detectors last a full year if we get rid of their antiquated and inefficient 9V packs.

P.S.: America, think about migrating to 220-240VAC outlets someday. The fewer standards, the better. You can make USB wall outlets standard at the same time!

Re: The humble USB cable is part of an electrical revolution

#30

Post by nickff »

sliverstorm wrote: post #19
x0x0 wrote: post #5

Earlier quoted context omitted.

(I'm not an engineer). I a similar article; iirc android phones could be owned by plugging them into a hostile usb connection. I wonder, though, if you couldn't produce a simple adapter that just drops some of the pins? Maybe I don't know enough about usb.

You can make a power-pin-only USB connector, but I believe that precludes requesting high-current mode (i.e. you are stuck in 100mA mode)

Most hosts will provide at least 500mA without any signal from a device. Hosts and chargers vary in their current capability; those capable of providing more than standard USB spec vary in their implementation. In general, high current hosts always provide their full capability, and the devices are the ones which require some signal to indicate maximum current available. Other devices increase their current draw until the host's voltage drops, and hold at that level (or less).
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