Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Facebook crawls links in PDFs you send in Messenger

twitter.com

Post reply on HN
Print view View original

81–90 of 165 posts

Re: Facebook crawls links in PDFs you send in Messenger

#81

Post by mehrdadn »

Nextgrid wrote: post #56
st0le wrote: post #55

Earlier quoted context omitted.

Honestly, This is good to prevent malware but I imagine this breaks a bunch of things if for eg. If the link has a limited visit count. The link will "expire" before the recipient gets a chance to view it.

To be fair, an HTTP GET request should never modify the state of the system - hitting a link should not change anything. If you need to expire links then make the initial link display a form with a submit button (which does a POST) to reveal the content (and expire the link). Legitimate crawlers don’t submit forms so it should be safe.

> To be fair, an HTTP GET request should never modify the state of the system

In theory. But that's not how the world I live in seems to work.

Re: Facebook crawls links in PDFs you send in Messenger

#82

Post by journalctl »

knzhou wrote: post #30
criddell wrote: post #4

Microsoft does this with Skype too. They say it's for detecting malicious links.

As always in big tech, you're damned if you do and damned if you don't.

So they might as well don’t; at least then we get some modicum of privacy.

Re: Facebook crawls links in PDFs you send in Messenger

#83

Post by axegon_ »

worldofmatthew wrote: post #26

This should not be news to anyone. Facebook scans all links posted in Messenger.

This. I honestly don't get why this is news. I truly hate facebook with a passion, I really do. But on this occasion I don't really blame them: You know what you are getting yourself into, what did you expect? A tuna salad? You shouldn't really be sharing any personal information on any platform which you can't hold accountable, regardless of e2e encryption.

Re: Facebook crawls links in PDFs you send in Messenger

#84

Post by BubRoss »

yellow_lead wrote: post #68
javagram wrote: post #36

This will keep happening until they enable e2e. I’ve had Facebook block several links sent in private message groups, to completely legal and safe sites (Messenger prints out an obscure API error and refuses to send the content). They have done this for a long time.

I experienced this too, Facebook will block most torrent links, regardless of if they're legal or not. I've taken to encoding these with Base64 first and instructing the recipient to decode them.

Why not just make it a broken link and tell them how to correct it?

Re: Facebook crawls links in PDFs you send in Messenger

#85

Post by BubRoss »

SlowRobotAhead wrote: post #67
0xffff2 wrote: post #62

Earlier quoted context omitted.

If the link was still blocked it would guarantee that Facebook is still eavesdropping.

Other guy was right. Think about this easy scenario If (E2E_ENABLED) { SkipCrawler(); SkipContentChecks(); }

Again, it isn't to prove the encryption works, it is only a test that could prove that it doesn't work.

Re: Facebook crawls links in PDFs you send in Messenger

#86

Post by datameta »

BubRoss wrote: post #84
yellow_lead wrote: post #68

Earlier quoted context omitted.

I experienced this too, Facebook will block most torrent links, regardless of if they're legal or not. I've taken to encoding these with Base64 first and instructing the recipient to decode them.

Why not just make it a broken link and tell them how to correct it?

I imagine it is quite easy to reassemble a broken link with some extra whitespace or random characters (unless you really scramble it which makes the process of manually "decoding" tedious). At that point you might as well automate the process and use base64

Re: Facebook crawls links in PDFs you send in Messenger

#87

Post by kerng »

javagram wrote: post #36

This will keep happening until they enable e2e. I’ve had Facebook block several links sent in private message groups, to completely legal and safe sites (Messenger prints out an obscure API error and refuses to send the content). They have done this for a long time.

Same can be done if e2e is enabled. Nothing prevents Facebook from sending links from client to a "validation" service.

They do this already in WhatsApp for instance.

Re: Facebook crawls links in PDFs you send in Messenger

#88

Post by egypturnash »

Barrin92 wrote: post #80
djohnston wrote: post #70

And if they didn't the headline would read: "Facebook fails to stop malicious and illegal content from being shared on their Network! Should they be shut down?!"

this sounds like a strawman to be honest because I haven't heard anyone rant about illegal music since probably 15 years, and if anything ever only politicians and not ordinary people. If we'd be talking really malicious stuff like chid pornography then in the context of filesharing these companies already have systems in place to distinguish content, so blanket banning of torrent files seems blatantly unnecessary.

Malicious content could also include phishing and viruses.

Re: Facebook crawls links in PDFs you send in Messenger

#89

Post by odensc »

supernova87a wrote: post #66
_8j50 wrote: post #44

Not in the least surprising. Wouldn't be surprised if Gmail does this to..."detect phishing" (pdfs containing phish links are common). Always a plausible reason they can use.

There's no surprise. Gmail does. If you search for a text string in Gmail, it will return emails that contain that text only in scanned images or PDFs that are in your mailbox.

That doesn't mean they're crawling the URLs, just that they're indexing the content of PDFs/images for your search. Which is, honestly, a pretty useful feature. Whereas Facebook is doing this without providing any value to the user.
Post reply on HN