Can't see the wood for the trees
> There are various possible attack scenarios ... posting a number of images online and waiting for them to be scraped by a crawler, which would poison the resulting model given the ingestion of enough sabotaged images.
> "Where these attacks are really scary is when you're getting web scraped datasets that are really, really big, and it becomes increasingly hard to verify the integrity of every single image."
So:
* you are scraping the web for damn near every image you can lay your hands on (there will be some filtering applied - don't bother with the 1x1 tracking images, for example - but broadly speaking, every image).
* some sort of data within an image counts as "poison" and you only need a very small percentage of that to ruin your dataset
* up until now, nobody knew what this "poison" looked like, so nobody could have been on the lookout for it[1]
* random images scraped from random places *will* have random data in them[2]
* Now, what are the chances that some of the images you have all already consumed aren't accidentally, randomly, poisonous and all your datasets are already deadly if eaten in excess?
For that matter,
> hard to verify the integrity of every single image
if you're taking arbitrary images, what on Earth does it even mean to say you are "verifying the integrity of the image"? An image can be anything, absolutely anything at all, that is sort of the point of images, and expressing art in your images!
If, on the other hand[3], your "integrity of the image" *really* just means "a malformed file, the PNG standard says that byte should really be..." then you aren't talking about "poisoning images", you are talking about "your image parser is rubbish, what, did you copy out of the UEFI code?" in which case the scrapers should be subjected to Howls of Derisive Laughter, Bruce.
[1] even assuming that they *can* be on the lookout for it - I haven't read the preprint properly yet: it is possible that this "poisoning" is like some of the old antagonistic image changes, where they just fuzzed the image until the classifier puked, but never actually understood what was going on inside the the blackbox 'Network that upset it so. So those trials didn't provide a description of what was important about the changes and therefore what you could do to look out for similar "poisons". That is, they had a demonstration as Proof of Concept "you can ruin the results" and that was it.
[2] You say that I've poisoned that photograph, I say I just went at it with GIMP for artistic effect.
[3] As I said, will get around to reading the preprint, but right now...