Facebook crawls links in PDFs you send in Messenger
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Re: Facebook crawls links in PDFs you send in Messenger
#2Could someone effectively DOS another site using this method by including a bunch of links that generate a lot of load?
Would be interesting to see if Facebook has a maximum number of links it'll follow.
Re: Facebook crawls links in PDFs you send in Messenger
#3Could someone effectively DOS another site using this method by including a bunch of links that generate a lot of load? Would be interesting to see if Facebook has a maximum number of links it'll follow.
I remember something like this was possible back in the day with Google Sheets. You could embed a URL as if it was an image in each cell of a sheet and it would make thousands of requests. I don't remember the details.
Re: Facebook crawls links in PDFs you send in Messenger
#4Microsoft does this with Skype too. They say it's for detecting malicious links.
Re: Facebook crawls links in PDFs you send in Messenger
#5Sidenote i wonder why FB doesnt launch a search engine since they crawl most of the web anyways
Re: Facebook crawls links in PDFs you send in Messenger
#6Huh, but why?
I can totally understand scanning a PDF for links to look for malicious links to protect users.
But that wouldn't involve actual HTTP requests to them.
I'm struggling to imagine what purpose this could have.
Re: Facebook crawls links in PDFs you send in Messenger
#7Sidenote i wonder why FB doesnt launch a search engine since they crawl most of the web anyways
That would let people leave the Facebook platform and explore the open web.
Re: Facebook crawls links in PDFs you send in Messenger
#8Huh, but why? I can totally understand scanning a PDF for links to look for malicious links to protect users. But that wouldn't involve actual HTTP requests to them. I'm struggling to imagine what purpose this could have.
The malicious links could be camouflaged behind a redirect.
Re: Facebook crawls links in PDFs you send in Messenger
#9Huh, but why? I can totally understand scanning a PDF for links to look for malicious links to protect users. But that wouldn't involve actual HTTP requests to them. I'm struggling to imagine what purpose this could have.
The obvious argument is they need to scan pages linked for malware and couldn't rely on a white/black list.
I'm sure if they're pulling data to do this analysis, it's not the only analysis they're doing.
Re: Facebook crawls links in PDFs you send in Messenger
#10Huh, but why? I can totally understand scanning a PDF for links to look for malicious links to protect users. But that wouldn't involve actual HTTP requests to them. I'm struggling to imagine what purpose this could have.
How do you know if they're malicious if you don't make HTTP requests to them?
One of the things that phishers and others do is use link wrapping and other services to hide malicious links. So, I get something.wordpress.com/something-clean. I then put in an HTML or JS redirect on that page to something malicious. Given that browsers don't warn about HTTP, HTML, or JS redirects, it's an easy way for scammers to get around a list of malicious pages.
These kinds of attacks are very common in the email space.