Exploit Vendor Drops Tor Browser Zero-Day on Twitter (zdnet.com)

An anonymous reader writes: Zerodium, a company that buys and sells vulnerabilities in popular software, has published details today on Twitter about a zero-day vulnerability in the Tor Browser, a Firefox-based browser used by privacy-conscious users for navigating the web through the anonymity provided by the Tor network. The vulnerability is a bypass of the NoScript extension that's included by default with all Tor Browser distributions. Once bypassed, an attacker can run malicious code inside the Tor Browser, code that under certain circumstances would have been stopped by NoScript.

"This Tor Browser exploit was acquired by Zerodium many months ago as a zero-day and was shared with our government customers," Zerodium CEO Chaouki Bekrar told ZDNet in an interview. "We have decided to disclose this exploit as it has reached its end-of-life and it's not affecting Tor Browser version 8 which was released last week." The NoScript extension released a patch in record time today to fix the vulnerability, two hours after Zerodium dropped its code on Twitter.

Comments

Rule One

[Anonymous Coward]

Rule one of Tor: disable javascript in about:config.

Re:Rule One

[Anonymous Coward]

Not saying you're wrong, but the reason many people use tor is to use the web. If it isn't useful for that, it's never going to get the kind of traction it needs among people "not doing anything wrong".

And if those people don't use it, all it does is paint a HUGE target on the backs of people who do... and who need it to protect themselves.

"Posts" not "drops"

[jabberw0k]

The link was posted (added), not dropped (removed).

Re:[offensive post removed]

[fleabay]

You're going to have to try harder to sow discontent around here with a fake deleted post and a fake account to try and make it look legit. People here are smarter than you.

Yay, NoScript!

[thomst]

There've been quite a number of posts beardmuttering about a severe NoScript vulnerability for much of the past couple of weeks. The fact is that, if you use the Tor browser at all regularly, you've been seeing a notification flag about that very thing in the addons bar for the whole of that time.

What I take from this story is that, although the existence of the vulnerability had to have been disclosed to the Tor developers - and very likely to the NoScript folks, as well - just prior to the appearance of that flag, it wasn't until today that the Zerodium folks disclosed the actual code to them. Now, if you know there's some kind of vulnerability that's been discovered, but you don't know exactly what that vulnerability consists of, it's pretty fucking difficult to fix the damned thing, because, essentially, you'd have to just blindly guess at its nature and where in your code it might be hiding.

Otherwise you'd just quietly fix it, push out an update, and get on with the task of developing the next version, rather than have to expend those resources on more bughunting. So, to me, the fact that the NoScript team produced a fix in two hours from the time Zerodium released the exploit code is a tribute to their commitment to protecting their users.

It also tells me that the fix itself must have been relatively trivial - which in no way diminishes my admiration for the devs who coded it, tested it, integrated it into the addon, and got it out the door in the duration of a typical garage band rehearsal.

So, good job, guys!

What does give me pause is Zerodium's casual disclosure that they had already thoroughly saturated their market for that exploit, and concluded that they couldn't squeeze another dollar out of the black hat sector (having previously sold it to every nation-state in the intelligence world - or, rather, every one in the market for zero-days). At a guess, that means they've been actively hawking it for not less than six months or so.

And that is a Very Bad Thing, indeed ...

Re:Yay, NoScript!

[Giorgio Maone]

The NoScript dev -- not "devs" ;) -- here.

Thank you for your commentary, which is quite to the point except for two details which I'd like to set straight:

• The existence of this vulnerability, let alone its nature, has never been disclosed neither to me or the Tor Browser team. The very first hint I had about it has been this tweet by the ZDNet reporter, sent about one later than Zerodium's one, and noticed even later.
• Based exclusively on that Zerodium's tweet (not a proper bug report, just a innuendo without even a link to a live PoC), the "NoScript team" (just me, actually) scrambled to create a reproducible test-case, dig in NoScript 5 "Classic"'s code base which had not been touched for months*, find the bug, fix it, test the patch, package two new versions (one for the beta autoupdate channel, one for the stable one) and deploy them both in quite less than one hour, real-time while been interviewed by the journalist. In the old days, when I had my own garage bands, our typical rehearsals were much longer -- and pleasant ;)

* NoScript 10 "Quantum" has been the main branch and the only I focused on since December 2017: it's a complete rewrite and was born unaffected by this bug. NoScript 5 has been kept around so far for the Tor Browser and the others based on Firefox ESR 52, like Palemoon.

I'd like also to add that NoScript 10's code is much simpler, leaner and easier to understand / maintain, and has got a lot more "friendly" eyeballs reviewing it for possible flaws. Therefore I'm quite confident something like this wouldn't go unnoticed that easily. Anyway, I vow to keep fixing whatever security bug is found (either cooperatively or in a hostile and disturbing way, like in this case) as fast as humanly possible, and even a bit faster, like I always did :)

Re:Yay, NoScript!

[SumDog]

It's rare to see the dev of a tool respond here on Slashdot. That's more typical on Hackernews. Seriously this place is a cesspit. :-P

But good on you, and thanks for clearing this up too. People don't get enough appreciation for this kind of work, especially porting your plugin to WebExtensions .. something that has been really challenging to quite a few plugin authors.

Thank you for your candour and information and setting the record straight.

End of life?

[Anonymous Coward]

Really weird when an exploit vendor says one of their exploits is reaching "end of life".

Also creepy that they are selling this to governments. I'd bet this sort of thing happens all the time from all sorts of shady companies like this.

bypasses a *legacy* NoScript

[DrYak]

From the mouth (well keyboard) of the NoScript dev himself, this is a bug which affects the old NoScript version 5, the XUL extension that is still used in a few old browsers still based on the Firefox 52 ESR (like Tor Browser).

The NoScript version 10, the Web Extension that works in more recent version of Firefox (they switched to Web Extensions exclusively since Firefox version 57), isn't affected.
Thus the current version of TorBrowser, version 8, which is based on FireFox ESR 60, is running an unaffected NoScript version. (Even the /. summary mentions this point).
Your current vanilla Firefox 62 / Firefox Android 62 isn't affected either.

Thank you

[DrYak]

The NoScript dev -- not "devs" ;) -- here.

Thank you, sir, for your work. You're making one of my most favorite extension ever
(The other being gorhill's uBlock Origin).