TIL: https://idioms.thefreedictionary.com/fall+off+a+truck

Edit: looking up a bit more, it seems like this idiom is used to denote goods sold for cheap because they were stolen. Like "Bob is selling genuine iPhones very cheap, I fear they fell from the back of a truck".

Edit edit: I initially took it as "we won't tell how we got this", because I didn't know this idiom, but it seems several people agree with this interpretation. Not necessarily stolen, but obtained from an undisclosed source.

That isn't quite right. Although it's commonly used to describe something that's been stolen, it's more generally used to indicate that the speaker doesn't want to talk about where it came from. That's how it's been used in this article.

Given the sort of business Cellebrite is in, they would probably still want to treat anything connected to it with an overabundance of caution.