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Bitwarden Heist – How to break into password vaults without using passwords

blog.redteam-pentesting.de

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Re: Bitwarden Heist – How to break into password vaults without using passwords

#31

Post by jabart »

RedTeamPT wrote: post #23
hypeatei wrote: post #6

I'm glad they made some improvements to security as a result of this finding. This "attack" is still very specialized though and requires local access which (as mentioned) could've exposed the user to keyloggers and other malware.

Yes, it requires an attacker in a powerful position with local access. However, it does not require special privileges or techniques that may trigger endpoint security (such as keyloggers or memory dumping). The only requirements are reading a JSON file and making a single Windows API call to retrieve the key.

It sounds like this required both local access AND a Active Directory Domain Administrator account (which should have triggered EDR at some point) which is the end game anyway. They just managed to hop out of the AD environment to a non-ad server because of the other password being in this vault. Glad they made it more user interactive to decrypt.

Re: Bitwarden Heist – How to break into password vaults without using passwords

#33

Post by kadoban »

jabart wrote: post #31
RedTeamPT wrote: post #23

Earlier quoted context omitted.

Yes, it requires an attacker in a powerful position with local access. However, it does not require special privileges or techniques that may trigger endpoint security (such as keyloggers or memory dumping). The only requirements are reading a JSON file and making a single Windows API call to retrieve the key.

It sounds like this required both local access AND a Active Directory Domain Administrator account (which should have triggered EDR at some point) which is the end game anyway. They just managed to hop out of the AD environment to a non-ad server because of the other password being in this vault. Glad they made it more user interactive to decrypt.

No, the final one only required local access as the user in question (this is mentioned after the one you're referring to that required AD Domain takeover).

Re: Bitwarden Heist – How to break into password vaults without using passwords

#34

Post by magicalhippo »

RedTeamPT wrote: post #24
harrygeez wrote: post #22

Earlier quoted context omitted.

There are a few convenient scapegoats here but ultimately in this case it is not biometric unlock that enabled this but rather characteristic of the Active Directory's design (I'm not sure I will call it a weakness). For Android and iOS if you forget your PIN code I believe you are screwed, as in no one can decrypt your device for you.

Actually it is not just an issue with AD design, but the AD design only makes it slightly worse. The underlying issue is that biometrics are not required to retrieve the biometric key from DPAPI and instead of authenticating with Windows Hello, any program could just simply ask DPAPI for the key.

My understanding from a quick reading is that Bitwarden essentially used Windows Hello to ask "is the user there" and if so, asked DAPI to give Bitwarden the secret vault credentials which it happily did because that's its job.

The problem with this was that the vault credentials in DAPI was not safe from other programs running as the user, nor from domain admins which could use the recovery key stored on the AD server (which they did in their attack after gaining admin access).

The solution was to use Windows Hello the way it was meant. That is, to store an asymmetric key pair, where the private key is hidden and protected by the biometrics or hardware security key, and use that to encrypt the secret vault credentials before storing them in DAPI.

Re: Bitwarden Heist – How to break into password vaults without using passwords

#35

Post by walki »

Microsoft's %Appdata% directory is a security nightmare in my opinion. Ideally applications should only have access to their own directories in %Appdata% by default. I recently came across a python script on GitHub that allows to decrypt passwords the browser stores locally in their %Appdata% directory. Many attacks could be prevented if access to %Appdata% was more restricted.

I also found a post of an admin a few days ago where he asked if there was a Windows setting for disallowing any access to %Appdata%. The response was that if access to %Appdata% is completely blocked Windows won't work anymore.

Re: Bitwarden Heist – How to break into password vaults without using passwords

#36

Post by 0xbadcafebee »

tl;dr

  This means that any process that runs as the low-privileged user session can simply ask DPAPI for the credentials to unlock the vault, no questions asked and no PIN or fingerprint prompt required and Windows Hello is not even involved at all. The only caveat is that this does not work for other user accounts.
Yikes

  Bitwarden has since made changes to their codebase to mitigate this particular scenario, which we will quickly summarize in the next section. They have also changed the default setting when using Windows Hello as login feature to require entering the main password at least once when Bitwarden is started.
Phew

Props to the security researchers for finding this bug! It's great that we have the infosec community to help protect us. Feels like one of the few industries whose monetary incentive is to help the public.

Re: Bitwarden Heist – How to break into password vaults without using passwords

#37

Post by SV_BubbleTime »

jabroni_salad wrote: post #25
gtirloni wrote: post #9

> As usual, we managed to get administrative access to the domain controller As usual? Is that the state of Windows Server security these days? I never managed a Windows-based network so I have no idea. I heard about these things back in the 2000's but I'm surprised this is "usual".

Yes. If you have LLMNR, NTLM enabled, unsigned SMB allowed, and nonencrypted LDAP bindings then your domain controller can be popped with zero effort by metasploit. Legacy protocols can be very sticky and most repeat pentest engagements I am able to use the same exact method every time because they will never get addressed. Modern windows (since like vista-era) will use better stuff out of the box but will also allow…

>Hell, I still find SMBv1 in a lot of places.

It cost me thousands of dollars last year to get our MSP to disable SMBv1 and force correct policies. They "Needed to audit for a week" to make sure this "didn't break older software". It was annoying I even had to ask that they didn't come to me saying "We won't support you if you have SMBv1 enabled".

Re: Bitwarden Heist – How to break into password vaults without using passwords

#38

Post by charcircuit »

jabroni_salad wrote: post #25
gtirloni wrote: post #9

> As usual, we managed to get administrative access to the domain controller As usual? Is that the state of Windows Server security these days? I never managed a Windows-based network so I have no idea. I heard about these things back in the 2000's but I'm surprised this is "usual".

Yes. If you have LLMNR, NTLM enabled, unsigned SMB allowed, and nonencrypted LDAP bindings then your domain controller can be popped with zero effort by metasploit. Legacy protocols can be very sticky and most repeat pentest engagements I am able to use the same exact method every time because they will never get addressed. Modern windows (since like vista-era) will use better stuff out of the box but will also allow…

Why hasn't Microsoft at least sandboxed these protocols if they are so bad in regards to security?

Re: Bitwarden Heist – How to break into password vaults without using passwords

#39

Post by jabart »

kadoban wrote: post #33
jabart wrote: post #31

Earlier quoted context omitted.

It sounds like this required both local access AND a Active Directory Domain Administrator account (which should have triggered EDR at some point) which is the end game anyway. They just managed to hop out of the AD environment to a non-ad server because of the other password being in this vault. Glad they made it more user interactive to decrypt.

No, the final one only required local access as the user in question (this is mentioned after the one you're referring to that required AD Domain takeover).

Ah yeah.

1. Off workstation decrypt using the AD DPAPI Backup keys. 2. Local DPAPI List and Dump for the windows hello biometric key

Re: Bitwarden Heist – How to break into password vaults without using passwords

#40

Post by SV_BubbleTime »

gtirloni wrote: post #9

> As usual, we managed to get administrative access to the domain controller As usual? Is that the state of Windows Server security these days? I never managed a Windows-based network so I have no idea. I heard about these things back in the 2000's but I'm surprised this is "usual".

I promise if you are using Windows AD and haven't had a pen test and remediation in the last few years - you would lose to a decent pentesting group.
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