News for hackers. Stuff that matters.
Re:Malware can turn off webcam LED and record video, demonst... by MaxikCZ on Wednesday November 27, 2024 @04:16PM (#42259862)
A capacitor can hold enough charge to power led for noticable amount of time even if powered for a brief moment, no logic needed
Re:Malware can turn off webcam LED and record video, demonst... by squarefoot on Wednesday November 27, 2024 @06:10PM (#42260721)
I don't think they would waste a high value capacitor just to keep a led lit for longer, also a led directly lit by a capacitor would be noticeable by slowly dimming when the capacitor discharges. It's more likely that the signal driving the led comes out of a monostable implemented in code: pin_on() drives the led on; pin_off() waits n secs then drives the led off.
Re:Malware can turn off webcam LED and record video, demonst... by altairprime on Wednesday November 27, 2024 @09:12PM (#42261753)
This is Apple, so that assertion isn’t guaranteed valid like it would be for non-enterprise HP or Lenovo. They absolutely would invest in a capacitor if that’s what it takes, as they are maximally focused on camera privacy concerns and have made a point of that in their security marketing over time; or else they wouldn’t be allowing hardware security engineers to brag about it, much less talk publicly about it, at all.

EDIT: It’s not just a capacitor, it’s a full custom chip, that can’t be software-modified, that keeps the light on for 3 seconds. https://news.ycombinator.com/item?id=42260379

Re:Malware can turn off webcam LED and record video, demonst... by RA2lover on Wednesday November 27, 2024 @04:39PM (#42260053)
The trick is to keep using the camera until that capacitor is discharged. I'm pretty sure most cameras can run at voltages below a LED's forward voltage nowadays.
Re:Malware can turn off webcam LED and record video, demonst... by HeyLaughingBoy on Wednesday November 27, 2024 @10:34PM (#42262186)
Logic on an already existing ASIC is going to be cheaper than a capacitor.
Re:Malware can turn off webcam LED and record video, demonst... by MrDrMcCoy on Thursday November 28, 2024 @02:28AM (#42263263)
This is counter-intuitive enough to warrant further explanation.
Re:Malware can turn off webcam LED and record video, demonst... by ale42 on Thursday November 28, 2024 @06:04AM (#42264352)
If you are designing an ASIC for the camera, you can include all the required logic gates to control the LED for a cost that is close to zero. It wouldn't impact the production cost of the ASIC, whereas a capacitor is an additional item in the BOM (and to be charged it requires current, more than the LED, so the driver in the IC must be bigger).