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Cloudflare Reverse Proxies Are Dumping Uninitialized Memory

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Re: Cloudflare Reverse Proxies Are Dumping Uninitialized Memory

#511
post #471

Earlier quoted context omitted.

You don't have to use scrapers, just use copies of the TLD zone files looking for cloudflare nameservers.

This will not cover all sites[1]. 1. https://support.cloudflare.com/hc/en-us/articles/202320534-C...

Huh TIL. Good call!

Re: Cloudflare Reverse Proxies Are Dumping Uninitialized Memory

#512
post #154

Earlier quoted context omitted.

correct

Have you asked them for an eta on your shirt?

You know a company isn't serious about security when their top security bounty is a t-shirt. Instagram has a better policy, for God's sake.

Re: Cloudflare Reverse Proxies Are Dumping Uninitialized Memory

#513
Apparently, the only way to change one's Uber password is to use the 'Forgot password' path on their login page.

So, I clicked on that - and I get a 500 error from NGINX.

My guess is that a lot of services are going to be overwhelmed by the sheer volume of password reset requests, thus preventing users from resetting their passwords.

Re: Cloudflare Reverse Proxies Are Dumping Uninitialized Memory

#514

This is probably a good moment to recall the article I published a while ago about how CloudFlare is actively putting the web at risk: http://cryto.net/~joepie91/blog/2016/07/14/cloudflare-we-hav... This is precisely why. The only thing that surprises me about this, is that it was an accidental disclosure rather than a breach. Other than that, this was completely to be expected . EDIT: Also, this can't be repeated en…

I can't change my Uber password - first, the only way to do so is via the 'Forgot your password' dialogue, and second, that now produces a 500 error from NGINX.

Lots of services are going to crumple under the weight of frantic password-reset requests.

Re: Cloudflare Reverse Proxies Are Dumping Uninitialized Memory

#515

From Twitter: "@taviso their post-mortem indicates this would've been exploitable only 4 days prior to your initial contact. Is that info invalid?" - https://twitter.com/pmoust/status/834916647873961984 "@pmoust Yes, they worded it confusingly. It was exploitable for months, we have the cached data." - https://twitter.com/taviso/status/834918182640996353

From my blog on this: The three features implicated were rolled out as follows. The earliest date memory could have leaked is 2016-09-22. 2016-09-22 Automatic HTTP Rewrites enabled 2017-01-30 Server-Side Excludes migrated to new parser 2017-02-13 Email Obfuscation partially migrated to new parser 2017-02-18 Google reports problem to Cloudflare and leak is stopped

not trolling, I followed your HN profile link: what blog post? http://blog.jgc.org/

Re: Cloudflare Reverse Proxies Are Dumping Uninitialized Memory

#516

Earlier quoted context omitted.

This assumes that the Bad Guys hadn't noticed the bug before Tavis, and hadn't started intensively mining Cloudflare for data.

Intensive mining indeed, if it's true that it requires 3.3M requests to get a page leak. With a fixed 100Mbps connection and assuming 2kB per HTTP request-response, you can hope to get one leak every 11 minutes and 6.6GB of traffic, which is a constant 5k requests/s. Maybe if Google reassigns all its SHAterred ressources to doing that... ... and then I realize that we were talking about cloudflare and my mining bot a…

That's what was observed on the Cloudflare end. Without the multiplicand of how many pages Cloudflare served in a given amount of time, you can't determine the impact. Assuming that affected sites were affected en masse, a targeted attack from a connection would be minuscule compared to the pages Cloudflare serves.

Cloudflare is serving up more than 100Mbps; the attacker only has to zero in on what's fruitful, which yields something far higher than the 1 per 3.3M Cloudflare sees serving millions of innocuous requests.

Re: Cloudflare Reverse Proxies Are Dumping Uninitialized Memory

#517
post #91
post #79

Earlier quoted context omitted.

In case you're wondering how this could be worse than Heartbleed: Yes, apparently the allocation patterns inside Cloudflare mean TLS keys aren't exposed to this vulnerability. But Heartbleed happened at the TLS layer. To get secrets from Heartbleed, you had to make a particular TLS request that nobody normally makes. Cloudbleed is a bug in Cloudflare's HTML parser, and the secrets it discloses are mixed in with, appa…

It shouldn't be too difficult to feed an instrumented copy of the parser some fraction of their cached pages (after all, that's what they're for.. right?) and calculate a percentage of how many triggered e.g. valgrind, or just some magic string tacked on the end of the input appearing in the output or similar I prefer CloudScare to Cloudbleed :)

Cloudflush.

Re: Cloudflare Reverse Proxies Are Dumping Uninitialized Memory

#518
post #4

Oh, my god. Read the whole event log. If you were behind Cloudflare and it was proxying sensitive data (the contents of HTTP POSTs, &c), they've potentially been spraying it into caches all across the Internet; it was so bad that Tavis found it by accident just looking through Google search results. The crazy thing here is that the Project Zero people were joking last night about a disclosure that was going to keep e…

Can someone tell me the implications of this in laymen terms? For instance what does it mean "sprayed into caches"? what cache? dns cache? browser cache? if the latter, does it mean you are safe if the person who owns that cache is an innocent non technical iser?

Many services on the internet keep a copy of a page they have loaded in the past. Google does this, for example. It lets them do things like search across websites quickly.

Many of these caches are available online, to anyone who wants to look at them.

This bug meant that any time a page was sent through Cloudflare, the requester might receive the page plus some sensitive personal information, or credentials that could be used to log in to a stranger's account. Some of these credentials might let a bad actor pretend to be a service like Uber or Fitbit.

This very sensitive information might end up saved in a public cache, where anyone could find it and use it to do harm.

Re: Cloudflare Reverse Proxies Are Dumping Uninitialized Memory

#519
post #488
post #404

Earlier quoted context omitted.

It's about payoff * probability. Let's say I (an idiot, but knowledgeable enough) stumble upon a serious vulnerability in Google. Option 1: I could try to sell that on a darknet market for a decent amount of money. State actors, hacker groups, lots of people want to pay for such things to exploit. But, I might not get paid very much, I might get screwed over, I might go to jail, who the heck knows, I'm playing with a…

> I might go to jail Is selling exploits illegal? If so is selling them to google also illegal?

Telling Google about exploits in Google services in exchange for money is not illegal.

Telling them about exploits in other services in exchange for money might be, depending on context.

Your parent was talking about the former case.

Re: Cloudflare Reverse Proxies Are Dumping Uninitialized Memory

#520
Cloudfare's bug bounty maximum reward[1]:

1. Recognition on our Hall of Fame.

2. A limited edition CloudFlare bug hunter t-shirt. CloudFlare employees don't even have this shirt. It's only for you all. Wear it with pride: you're part of an exclusive group.

3. 12 months of CloudFlare's Pro or 1 month of Business service on us.

4. Monetary compensation is not currently offered under this program.

Guessing they're gonna reconsider #4 at this point.

[1] https://hackerone.com/cloudflare

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