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

The Tech Behind Dropbox’s New User Experience on Mobile, Part 2

tech.dropbox.com

Post reply on HN
Print view View original

21–30 of 37 posts

Re: The Tech Behind Dropbox’s New User Experience on Mobile, Part 2

#21

Post by shawn-butler »

ksb wrote: post #4
ChikkaChiChi wrote: post #3

Fascinating stuff, but was this a problem in need of a solution? Was Dropbox seeing that many issues with people running the install on their local machine? Were they able to differentiate between those who felt the install was a hassle versus those who simply opted to not install it?

There are a lot of places that we were seeing users drop off the radar when trying to install. Through a combination of logging analytics and user studies we figured out what the main problems were and designed this flow to solve them. (See my post from last week for more context on why we built this: https://news.ycombinator.com/item?id=8168792 )

>> Instead, we created a custom version of the signing tools which complied with the Authenticode spec (for Windows) while letting us safely modify content for each binary. Our custom tool allows us to create an unverified section of the binary in a way that is compliant with the Authenticode spec. >>

Can you offer some more info on this topic in a follow-up post?

Re: The Tech Behind Dropbox’s New User Experience on Mobile, Part 2

#22

Post by bronson »

vdaniuk wrote: post #19
[deleted] wrote: post #2

[deleted]

I've been monitoring HN reactions to Dropbox news with interest and I can conclude that mentioning Rice in comments has fallen out of vogue and is punished with downvotes of power users. HN was outraged at first, now it's meh about the whole deal. A regrettable development that shows companies that one can easily alienate a part of its early adopters, but bad rep won't stick if you continue to ship shiny things.

Gotta wonder about Dropbox and HN both being YC projects... Think that helps Rice be a non-issue?

Re: The Tech Behind Dropbox’s New User Experience on Mobile, Part 2

#23

Post by lnanek2 »

Honestly, I find their mobile offering really disappointing. Several times I've wanted to do things with it and not been able to, like login using only the mobile app and download some pictures I backed up for my wife, etc.. They don't seem to see the mobile app as a real, full app. This connect to desktop thing just makes it even worse. I didn't have my laptop around at the time. We've had other big issues with it involving the iPad version not being able to do things.

Re: The Tech Behind Dropbox’s New User Experience on Mobile, Part 2

#24

Post by dang »

bronson wrote: post #22
vdaniuk wrote: post #19

Earlier quoted context omitted.

I've been monitoring HN reactions to Dropbox news with interest and I can conclude that mentioning Rice in comments has fallen out of vogue and is punished with downvotes of power users. HN was outraged at first, now it's meh about the whole deal. A regrettable development that shows companies that one can easily alienate a part of its early adopters, but bad rep won't stick if you continue to ship shiny things.

Gotta wonder about Dropbox and HN both being YC projects... Think that helps Rice be a non-issue?

Certainly not in any way that I'm aware of.

Re: The Tech Behind Dropbox’s New User Experience on Mobile, Part 2

#25

Post by chrissnell »

timbre wrote: post #12

I'm surprised you can sign an executable, then modify it while preserving the validity of the signature, as I always though this is exactly what code signing is meant to prevent. Can anyone who knows more about this than me (a low bar!) explain whether this is a flaw in the signing mechanism or is actually okay?

More importantly, what good is a code-signed executable when that executable can simply download a payload from the internet like this Dropbox installer does? Code signing seems like a feel-good mechanism for users. Yeah, we guarantee that the executable that you downloaded was signed by a legitimate entity but once you run it, good luck. This type of "meta installer" seems ripe for exploitation. Unscrupulous entities create a legit signed app that later downloads a malicious payload; legitimate distributors might also find themselves to be the target of attackers who want to alter that downloadable payload.

Re: The Tech Behind Dropbox’s New User Experience on Mobile, Part 2

#26

Post by ipython »

timbre wrote: post #12

I'm surprised you can sign an executable, then modify it while preserving the validity of the signature, as I always though this is exactly what code signing is meant to prevent. Can anyone who knows more about this than me (a low bar!) explain whether this is a flaw in the signing mechanism or is actually okay?

Neat. Just tried downloading an installer and figured out that it's using the unauthenticatedAttributes structure of the Authenticode signature.

These attributes are not part of the signedAttributes which is used to actually authenticate the signature. A quick dump of the asn.1 structure of the authenticode signature block from my installer shows that right after the timestamp extension is a new object with a private OID (presumably assigned to dropbox for this purpose) that includes a unique string.

6519 11: OBJECT IDENTIFIER '1 3 6 1 4 1 42921 1 2 1' 6532 1049: SET { 6536 1045: UTF8String : 'Dropbox-Installer-Id:DBPREAUTH::msie::xxxx..........................................'

Interesting hack, kudos!

Re: The Tech Behind Dropbox’s New User Experience on Mobile, Part 2

#27

Post by okpl »

dang wrote: post #24
bronson wrote: post #22

Earlier quoted context omitted.

Gotta wonder about Dropbox and HN both being YC projects... Think that helps Rice be a non-issue?

Certainly not in any way that I'm aware of.

"...while letting us safely modify content for each binary. Our custom tool allows us to create an unverified section of the binary in a way that is compliant with the Authenticode spec."

quite an intriguing attack surface for mobile malware...arbitrary code of Dropbox's choosing when combined with an 0day or two?

Re: The Tech Behind Dropbox’s New User Experience on Mobile, Part 2

#28

Post by timbre »

chrissnell wrote: post #25
timbre wrote: post #12

I'm surprised you can sign an executable, then modify it while preserving the validity of the signature, as I always though this is exactly what code signing is meant to prevent. Can anyone who knows more about this than me (a low bar!) explain whether this is a flaw in the signing mechanism or is actually okay?

More importantly, what good is a code-signed executable when that executable can simply download a payload from the internet like this Dropbox installer does? Code signing seems like a feel-good mechanism for users. Yeah, we guarantee that the executable that you downloaded was signed by a legitimate entity but once you run it, good luck. This type of "meta installer" seems ripe for exploitation. Unscrupulous entitie…

I think the point of code signing is to ensure that the program was really written by Dropbox, so _if_ you trust Dropbox you should trust the program. That trust should definitely include both Dropbox's good intentions and their competency to prevent their payload system from being subverted.

Re: The Tech Behind Dropbox’s New User Experience on Mobile, Part 2

#30

Post by deciplex »

dang wrote: post #24
bronson wrote: post #22

Earlier quoted context omitted.

Gotta wonder about Dropbox and HN both being YC projects... Think that helps Rice be a non-issue?

Certainly not in any way that I'm aware of.

Unfortunately, we have to take your word for it, because there is no transparency of which of the various uncountable "bans" are associated with your account, to say nothing of why they are put there in the first place. You're probably not punishing posters for reminding people that Dropbox is an enthusiastic supporter of illegal domestic NSA spying operations, but there is no way to know that, either.

Trust, but verify^H^H^H^H^H^H^H^H^H^H in other words.

Post reply on HN