Hak5 O.MG Malicious Cable Detector found something

[TPCEA]

Hi! Black Friday afforded me many great deals, amongst them this item. Curiosity has revealed to me a cable that seems to be malicious. It's USB A to C. Should such a cable have anything other than wiring in it? When I plugged it in, the light flickered on and off (not bright, maybe 1-3x/second), and nothing was plugged in to the other end. I also tested another USB A to C cable, and the cable for my webcam, neither of which caused this.



The A side of course had a larger junction cover, but it was very tightly mounted and I couldn't remove it so I used my rotary tool to cut through the plastic. Underneath was soft rubber, which I removed with a knife, but nothing other than wires were there.

The C side had a small cover over the junction between plug and cable, and that cover was loose enough that it came off by itself months ago. Hidden under the rubber on that side was a tiny PCB. Now, I have no idea what that PCB is for, nor do I recall which device it came with, sadly.

So, is this one legit and needs a PCB to work, making the other one a much slower, fake USB A to C, or is the other one legit and this one is malicious?

 

[Bill_Bright]

I see nothing that concerns me.

 

[TPCEA]

I see nothing that concerns me.

That is the consensus, so O.MG's detector gave a false positive. LOL!

 

[Calenhad]

That is the consensus, so O.MG's detector gave a false positive. LOL!

No technology works 100%. A false positive once in a while is expected.

The pcb is likely for speed (and or charge capability) negotiation, notice there is a SMD between a couple pins in the larger image.

 

[Jacky_BEL]

The resistor value signals the USB controller what protocol/speed to use.
The USB controller detected the resistor and tried to read the USB descriptor from the USB "device", and since it is a dumb cable, nothing else happened.

Termination Resistors Required for the USB Type-C Connector – KBA97180

A downstream facing port (DFP), such as a host computer, exposes pull-up terminations, Rp, on its CC pins (CC1 and CC2). An upstream facing port (UFP), such as a peripheral, exposes pull-down terminations, Rd, on its CC pins. The purpose of Rp and Rd terminations on CC pins is to identify the DFP to UFP connection and the CC pin that will be used for communication. To do this, the DFP monitors both CC pins for a voltage lower than its unterminated voltage.

The Type-C cable needs to expose a pull-down termination, Ra, on its VCONN pin to signal to the DFP that it needs power. The DFP must be able to differentiate between the presence of Rd and Ra to know whether there is a UFP attached and where to apply VCONN. The DFP is not required to source VCONN unless Ra is detected.

When the connection detection phase is complete, Cypress’ CCG1 and CCG2 devices have the ability to remove the Ra resistor, which will reduce the overall power dissipation of a Type-C system design.

 

[TPCEA]

No technology works 100%. A false positive once in a while is expected.

The pcb is likely for speed (and or charge capability) negotiation, notice there is a SMD between a couple pins in the larger image.

Yeah, but they should've noted that USB-C can cause it.

Right, the SMD is a resistor noted by "R1".

 

[Jacky_BEL]

Yeah, but they should've noted that USB-C can cause it.

Right, the SMD is a resistor noted by "R1".

Most likely of a 1 kOhm value.

 

[TPCEA]

Most likely a 1 kOhm value.

In the days of my youth, all resisters were somewhat bulbously cylindrical and were marked with colored bands that indicated the resistor's value. I guess that info is no longer given?

 

[Jacky_BEL]

SMD resistors can have a marking denoting their value. Maybe this one is not visible.
Not much room on the SMD resistor surface.

 

[TPCEA]

SMD resistors can have a marking denoting their value. Maybe this one is not visible.
Not much room on the SMD resistor surface.

They could mark it... I'd just have to pull out my magnifying glass!

 

[Jacky_BEL]

And maybe in this case, the marking is on the other non-visible side, was what I meant.

 

[freeagent]

What is this cable for?

 

[TPCEA]

What is this cable for?

What, you didn't read my OP? XD

 

[freeagent]

What, you didn't read my OP? XD

I read your OP. I just asked what it was for.

I have an iPhone, so this stuff is new to me.

But its cool, I don't need to know

 

[TPCEA]

I read your OP. I just asked what it was for.

I have an iPhone, so this stuff is new to me.

But its cool, I don't need to know

I use it for transferring data and charging devices. Definitely NOT as a garotte!

 

[Calenhad]

Yeah, but they should've noted that USB-C can cause it.

Right, the SMD is a resistor noted by "R1".

That USB C cable is wired identically to any USB 2.0 cable. The false positive should not come from the singular fact that it is USB C at one end. It is about as dumb a cable can be, and still qualify as a basic USB C charging/data cable. Your cable tester probably have something in the order of 1:100 false positives, which is what I would expect from a cheaper device like that.

Higher spec USB C cables will have actual ICs (not just a SMD resistor) inside the connectors to negotiate power and speed capabilities with the USB hosts at either end. Which is a yes to your original question if there should be anything other than wires inside the cable.

 

[TPCEA]

That USB C cable is wired identically to any USB 2.0 cable. The false positive should not come from the singular fact that it is USB C at one end. It is about as dumb a cable can be, and still qualify as a basic USB C charging/data cable. Your cable tester probably have something in the order of 1:100 false positives, which is what I would expect from a cheaper device like that.

Higher spec USB C cables will have actual ICs (not just a SMD resistor) inside the connectors to negotiate power and speed capabilities with the USB hosts at either end. Which is a yes to your original question if there should be anything other than wires inside the cable.

How can I choose the better cables without spending a grand on a tester?

 

[Night]

It seems that more and more manufacturers aren't marking micro electronic parts anymore. Supposedly it's about the chemicals being used for the said process, in favor of enviromental protection.

 

[Calenhad]

How can I choose the better cables without spending a grand on a tester?

That is the million dollar question. Find cables that reliable testers have reviewed/dissected. Or at least buy from brands that are known to make good products. There are supposed to be markings on the packaging that tell you what specifications the cable is built to support. But the Chinese are much better at copying markings than the actual product.

This is one of the major issues with the USB C "standard". You have about a thousand different cable standards (I may have exaggerated a tiny bit for effect), and scammers know how to take advantage of this fact. And thanks to USB4 this has even gotten worse lately. Now you have the "same" cables for USB2.0, USB3.x, USB4, Thunderbolt 3, Thunderbolt 4, and plenty of different charging standards on top of that. Iirc USB4 and TB4 are supposedly the same cables, but we'll see how that works out.

 

[Jacky_BEL]

How can I choose the better cables without spending a grand on a tester?

Buy the cables from the known good manufacturers.