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Bitwarden PINs can be brute-forced

ambiso.github.io

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Re: Bitwarden PINs can be brute-forced

#101

Post by 8ytecoder »

SV_BubbleTime wrote: post #91
FfejL wrote: post #89

"Let's now assume that the user enables the PIN unlock and configures Bitwarden so that it doesn't require the master password on restart." If the user has setup Bitwarden so the master password is not required, then the user gets what they asked for, namely a password database secured by a 4 digit PIN. Not clear to me why this is a problem Bitwarden needs to fix.

They could make the pin process intentionally slow… maybe with some number of iterations… and as computers get faster they can just update the number of iterations required…

And add other defensive mechanisms like lockout after n retries.

Re: Bitwarden PINs can be brute-forced

#102

Post by lucb1e »

juve1996 wrote: post #32
chiefalchemist wrote: post #11

The moral of the story here seems to be: if you want convenience you'll compromise your security. This is not exclusive to BW. Or if you want a moral of the story specific to the article: Don't use the PIN feature in BW. And perhaps, instead of a PIN use a physical key (e.g., YubiKey).

Most people have been told that even though you're centralizing passwords (meaning if hacked you're in big trouble), the benefits gained from being able to generate strong passwords overcome this. Is this no longer true, for most people?

I would say this is definitely true for the common Joe, but of course it helps to not run much arbitrary software from the web and keep your browser up-to-date to avoid drive-by malware. If you've got a habit of pirating games, you may want to keep your princess in another castle.

My mom doesn't have any reason to download and run untrusted software ever, and she'd call me if she needs something, so for her it's definitely better to have secure passwords with the risk of having all eggs in one basket. The risk of her being tricked into running software that steals the vault is lower than the guessable and reused passwords that she used before.

If you are more like me and regularly download software to try it out, pull random github repos to toy with them, etc., then it might be wise to keep the password database on an Android/iOS device which have app isolation. You can download all the malware you want, but if you don't grant it root, it won't be able to access the database stored in /data/data/com.example.keepass/database/.

Re: Bitwarden PINs can be brute-forced

#103

Post by [deleted] »

morpheuskafka wrote: post #100
SV_BubbleTime wrote: post #91

Earlier quoted context omitted.

They could make the pin process intentionally slow… maybe with some number of iterations… and as computers get faster they can just update the number of iterations required…

If the PIN is local, only a secure element type of chip could meaningfully enforce this restriction. Otherwise, whatever memory or disk stores the secret encrypted only by the 4-digit PIN could still be brute forced. Just disabling entering a PIN in the UI would not be enough for security.

[deleted]

Re: Bitwarden PINs can be brute-forced

#104

Post by 0xdeafbeef »

morpheuskafka wrote: post #100
SV_BubbleTime wrote: post #91

Earlier quoted context omitted.

They could make the pin process intentionally slow… maybe with some number of iterations… and as computers get faster they can just update the number of iterations required…

If the PIN is local, only a secure element type of chip could meaningfully enforce this restriction. Otherwise, whatever memory or disk stores the secret encrypted only by the 4-digit PIN could still be brute forced. Just disabling entering a PIN in the UI would not be enough for security.

You can use pbdkf2 with 200k iterations or argon2 to derive key from pin

Re: Bitwarden PINs can be brute-forced

#105

Post by forty »

Of course the PIN can be brute forced. It feels like reporting "I can walk over the lawn fence". That PIN is probably here to prevent your kids from messing with your vault when you grab your coffee with your computer unlocked.

Protecting from an attacker with your laptop locked should be done at the OS level with FDE and secure boot. Protecting from a real attacker with access to your unlocked computer is a bit hopeless (as someone mentioned, they probably can install some key logger and steal the master password and everything else later).

It never hurts to be clear on the threat model (And they should probably go with the option 1. suggested by the author), but I feel in that case the behavior matches reasonable expectations and the author is a bit of bad faith.

For solution 2. if you want to check a pin server side without trivial access to the PIN from the server you can do it à la signal using secure enclaves https://signal.org/blog/secure-value-recovery/

Re: Bitwarden PINs can be brute-forced

#106

Post by nebulous1 »

SV_BubbleTime wrote: post #91
FfejL wrote: post #89

"Let's now assume that the user enables the PIN unlock and configures Bitwarden so that it doesn't require the master password on restart." If the user has setup Bitwarden so the master password is not required, then the user gets what they asked for, namely a password database secured by a 4 digit PIN. Not clear to me why this is a problem Bitwarden needs to fix.

They could make the pin process intentionally slow… maybe with some number of iterations… and as computers get faster they can just update the number of iterations required…

It already is intentionally "slow". However, for a 4 digit pin there are only 10 thousand combinations. It is not practical for it to be so slow that 10000x it is an infeasible amount of time. Not only would the user have to way too long on each entry, the attacker could just use faster hardware.

Re: Bitwarden PINs can be brute-forced

#107

Post by lucb1e »

Wowfunhappy wrote: post #22
billconan wrote: post #4

the more I see hacked password vaults (lastpass for example), the more I want to build a p2p password vault that only lives on my own devices.

I like self-hosting things, but for something as sensitive as my passwords I trust a professional company much more than I trust myself. Yes, companies can and do screw things up all the time, but that doesn't mean I would do better, and I'm a single person with other responsibilities in my life.

Or you don't host it but just keep it tight to your chest. No risk of any server being compromised then.

Professional companies that care about security (I do IT security consulting so that's the group I deal with the most) are not perfectly secure. I'd argue that it's less likely that a password database is abused when hosted on a random average-security system (assuming the person is not being targeted, like if you're not a public figure or have a stalker) than if you've got it hosted with some bigcorp that has a huge target painted on their back. Some are really good at security and others a bit less, but none are perfect, and scale dictates compromises between security and usability. Not everyone in the firm will be a security expert, and much as you try to isolate the vaults / source code / other security-relevant systems from them, they're how ransomware and other groups gain a foothold to work with.

I wouldn't trust my mom to set up a server secure enough for a password manager to be hosted on, but if you are comfortable around servers at all and follow normal guidelines, or use normal syncing software that is only encrypted to the server (so you pick and rely on a strong password for your vault file), you're more secure than when you use a third party and type that password into their website (even if, on a good day, the key stays local in your browser).

Re: Bitwarden PINs can be brute-forced

#108

Post by monocasa »

bkettle wrote: post #94
lucb1e wrote: post #81

Earlier quoted context omitted.

I web searched it and found a dedicated wikipedia page https://en.wikipedia.org/wiki/Interdiction but I still can't figure out what TPM interdiction is supposed to mean Anyway if a TPM was trivially bypassable then there would be no point to having them so I'm doubtful of whatever this off-hand comment is supposed to mean

I think they are talking about the definition under the Espionage section, i.e. a hardware supply chain attack: > The term interdiction is also used by the NSA when an electronics shipment is secretly intercepted by an intelligence agency (domestic or foreign) for the purpose of implanting bugs before they reach their destination.

I read the original comment instead about sniffing the data path between the TPM and the user to get the PIN.

Re: Bitwarden PINs can be brute-forced

#109

Post by barsonme »

0xdeafbeef wrote: post #104
morpheuskafka wrote: post #100

Earlier quoted context omitted.

If the PIN is local, only a secure element type of chip could meaningfully enforce this restriction. Otherwise, whatever memory or disk stores the secret encrypted only by the 4-digit PIN could still be brute forced. Just disabling entering a PIN in the UI would not be enough for security.

You can use pbdkf2 with 200k iterations or argon2 to derive key from pin

This has very limited benefit for weak passcodes, like PINs.

Re: Bitwarden PINs can be brute-forced

#110

Post by tomxor »

d-z-m wrote: post #20

The author mentions this finding was marked as out-of-scope when they reported it to Bitwarden. A couple of categories that are considered out-of-scope are listed, namely: attacks requiring physical access to a user's device, and "other side of airtight hatchway"[0] type issues. The latter seems reasonable, if the assumption is that the device is fully compromised, and ongoing surreptitious monitoring of user activit…

> users probably have the reasonable expectation that if their laptop is stolen

Yes, there is a significant difference between compromising a device with physical access and stealing the device. Disk encryption for example is very effective against the latter, but useless against the former. Having devices stolen is also far more common than targeted physical attacks.

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