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Comment by rory096 | Hacker News Reader

To Google Chrome's spellchecker. It's a bad vulnerability, but it's unlikely that it's really the attack vector here.

Official response by Coinomi

https://medium.com/coinomi/official-statement-on-spell-check...

Summary: Yes, there was a bug, we fixed it, but it was not exploitable in practice for a variety of reasons. Most importantly, the seed phrase wasn’t being transmitted in plain text.

Right. The "thief" would have to be extremely lucky to have been intercepting the right data, recognized what the key was, and used it. As mentioned in the story, I suspect this chap found the vulnerability and is hoping to parlay it into a payout.

No, more than that: assuming the connection to the spell checker uses TLS, the thief would have to be Google.

I'd be surprised if it doesn't use TLS?

The thief in that case would likely be a browser extension

It's a desktop app.

There was another instance of a massive coin theft a year or so ago and the weak link again was the recovery seed being sent to a Google server. The guy described his operational security and it seemed like he did everything right. The only slip up he could point to was that he had mistakenly pasted his seed into his Chrome address bar (which then performs an automatic lookup). It was shortly after that when his funds were drained.

I'm certainly not saying it was someone at Google, but it would be a mistake to not consider them an adversary in the battle to secure your funds.

A ton of people use GMail for their crypto accounts.

Claiming that someone at Google stole the funds is quite an extraordinary claim. You should have more proof than just the seed being sent to their spellchecker.

I'm not sure what the volume of gmail accounts is supposed to demonstrate. But gmail is known to be high value, and so it stands to reason that internal safeguards around access to gmail accounts would be much greater than data from a spellcheck API or search autocomplete.

It certainly is an extraordinary claim, but there does come a point where the totality of evidence points to the likelihood of it. I'm not saying we're at that point, but in my mind we've reached the point of reasonably possible.

Spellcheck API or autocomplete is also expected to end up with a ton of sensitive information sent to it. I would expect them to either not keep logs of the actual query strings to begin with, or heavily restrict access to them.

That's the weak link they knew about. It is very unlikely to be the actual weak link.

So, I'm not super familiar with crypto/blockchain beyond reading a couple academic papers but... how can you use it "offline"?

I saw someone in the parent comments mention that using your phrase on a machine connected to the internet can be risky... how can you make use of those coins then? Do you download some onto a usb to manually transfer over?

You identify yourself to the network as the legitimate owner of an address by signing a transaction with a private key for that address. So using your coins offline involves signing your transaction using a computer that is air-gapped and then manually transferring the signed transaction to the online computer to be pushed to the network. There are user friendly ways of doing this using QR codes and similar things.

Thanks for the explanation.

or wait for google to "anonymize" the data and release it internally for their researchers.

Yeah. This is pretty far-fetched.

> He argues that Coinomi’s built-in spell checker automatically checked his seed phrase which involved sending it as plain text to a Google-owned website. This meant it could have been intercepted, leading to the loss of funds.

"As plain text" here almost certainly means "fully encrypted with TLS"...

I felt like you did, and watched the video and he is certainly looking at an HTTPS data stream.

I think the argument though is that the request is being logged and that some employee is reviewing logs and grabbing data.

If that is the case, then it seems there is a known pool of suspects to charge with theft...

Yeah, and the amount of data to sift through there would be truly enormous.

I'd wager there was just some malware on the machine.

Apparently it's a list of 12 words from 2048. I guess you could potentially try and pattern match that, but that'd be a ton of a sifting.

The amount of data to sift through? What website am I on right now? Just grep for 64 character strings.

The regex is so simple I think it a little naive not to assume _someone_ has a script running to sniff out keys. It would be trivial for an ISP employee to watch for such strings in unencrypted traffic streams. Think what cloudflare could find if they went looking.

The stream isn't unencrypted, though. Chrome's cloud spellchecker sends over HTTPS, for obvious reasons. (It's also an opt-in feature.)

I strongly suspect grepping against inbound production traffic to Google's spellcheck service is fairly difficult to do unnoticed.

Malware, on the other hand, is quite prevalent. Plenty of folks lose their crypto on a daily basis in that manner.

Sure, but think of how porous this could be even with HTTPS-- it doesn't have to be a google admin grepping inbound traffic. It could be happening with a custom installed certificate for a workplace or university network or it could be happening with a third party service or API behind HTTPS termination. Even something trivial like analytics could potentially leak this info. Malware is certainly a possibility, but it could just as easily have been phished or grabbed with an XSS.

Access to this data is very tightly controlled, it's likely a single digit number of people.

Exactly. There's billions of entries there each day, it's just symptomatic of bad secops where the spellchecker upload is the canary for other rank stupidity.

Why in the world would they need a spell checker when the whole mnemonic phrase standard has a checksum (last word in every phrase is the checksum)

The Android EditText control has this enabled by default, and the documentation of the control doesn't mention it:

https://developer.android.com/reference/android/widget/EditT...

To disable it, the developer needs to add the "textNoSuggestions" flag to the input type.

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