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KETAMINE: Multiple vulnerabilities in SecureRandom(), numerous cryptocurrency products affected.
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ketamine--- via bitcoin-dev
2018-04-06 19:53:13 UTC
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A significant number of past and current cryptocurrency products
contain a JavaScript class named SecureRandom(), containing both
entropy collection and a PRNG. The entropy collection and the RNG
itself are both deficient to the degree that key material can be
recovered by a third party with medium complexity. There are a
substantial number of variations of this SecureRandom() class in
various pieces of software, some with bugs fixed, some with additional
bugs added. Products that aren't today vulnerable due to moving to
other libraries may be using old keys that have been previously
compromised by usage of SecureRandom().


The most common variations of the library attempts to collect entropy
from window.crypto's CSPRNG, but due to a type error in a comparison
this function is silently stepped over without failing. Entropy is
subsequently gathered from math.Random (a 48bit linear congruential
generator, seeded by the time in some browsers), and a single
execution of a medium resolution timer. In some known configurations
this system has substantially less than 48 bits of entropy.

The core of the RNG is an implementation of RC4 ("arcfour random"),
and the output is often directly used for the creation of private key
material as well as cryptographic nonces for ECDSA signatures. RC4 is
publicly known to have biases of several bits, which are likely
sufficient for a lattice solver to recover a ECDSA private key given a
number of signatures. One popular Bitcoin web wallet re-initialized
the RC4 state for every signature which makes the biases bit-aligned,
but in other cases the Special K would be manifest itself over
multiple transactions.


Necessary action:

* identify and move all funds stored using SecureRandom()

* rotate all key material generated by, or has come into contact
with any piece of software using SecureRandom()

* do not write cryptographic tools in non-type safe languages

* don't take the output of a CSPRNG and pass it through RC4

-
3CJ99vSipFi9z11UdbdZWfNKjywJnY8sT8
Matias Alejo Garcia via bitcoin-dev
2018-04-06 20:51:11 UTC
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Source?

On Fri, Apr 6, 2018 at 4:53 PM, ketamine--- via bitcoin-dev <
Post by ketamine--- via bitcoin-dev
A significant number of past and current cryptocurrency products
contain a JavaScript class named SecureRandom(), containing both
entropy collection and a PRNG. The entropy collection and the RNG
itself are both deficient to the degree that key material can be
recovered by a third party with medium complexity. There are a
substantial number of variations of this SecureRandom() class in
various pieces of software, some with bugs fixed, some with additional
bugs added. Products that aren't today vulnerable due to moving to
other libraries may be using old keys that have been previously
compromised by usage of SecureRandom().
The most common variations of the library attempts to collect entropy
from window.crypto's CSPRNG, but due to a type error in a comparison
this function is silently stepped over without failing. Entropy is
subsequently gathered from math.Random (a 48bit linear congruential
generator, seeded by the time in some browsers), and a single
execution of a medium resolution timer. In some known configurations
this system has substantially less than 48 bits of entropy.
The core of the RNG is an implementation of RC4 ("arcfour random"),
and the output is often directly used for the creation of private key
material as well as cryptographic nonces for ECDSA signatures. RC4 is
publicly known to have biases of several bits, which are likely
sufficient for a lattice solver to recover a ECDSA private key given a
number of signatures. One popular Bitcoin web wallet re-initialized
the RC4 state for every signature which makes the biases bit-aligned,
but in other cases the Special K would be manifest itself over
multiple transactions.
* identify and move all funds stored using SecureRandom()
* rotate all key material generated by, or has come into contact
with any piece of software using SecureRandom()
* do not write cryptographic tools in non-type safe languages
* don't take the output of a CSPRNG and pass it through RC4
-
3CJ99vSipFi9z11UdbdZWfNKjywJnY8sT8
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@ematiu
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Mustafa Al-Bassam via bitcoin-dev
2018-04-09 21:17:11 UTC
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And specifically, here's a version of it that uses Arcfour:
https://gist.github.com/jonls/5230850
Here's the code in question: https://github.com/jasondavies/jsbn/pull/7
Best,
Mustafa
Post by Matias Alejo Garcia via bitcoin-dev
Source?
On Fri, Apr 6, 2018 at 4:53 PM, ketamine--- via bitcoin-dev
A significant number of past and current cryptocurrency products
contain a JavaScript class named SecureRandom(), containing both
entropy collection and a PRNG. The entropy collection and the RNG
itself are both deficient to the degree that key material can be
recovered by a third party with medium complexity. There are a
substantial number of variations of this SecureRandom() class in
various pieces of software, some with bugs fixed, some with additional
bugs added. Products that aren't today vulnerable due to moving to
other libraries may be using old keys that have been previously
compromised by usage of SecureRandom().
The most common variations of the library attempts to collect entropy
from window.crypto's CSPRNG, but due to a type error in a comparison
this function is silently stepped over without failing. Entropy is
subsequently gathered from math.Random (a 48bit linear congruential
generator, seeded by the time in some browsers), and a single
execution of a medium resolution timer. In some known configurations
this system has substantially less than 48 bits of entropy.
The core of the RNG is an implementation of RC4 ("arcfour random"),
and the output is often directly used for the creation of private key
material as well as cryptographic nonces for ECDSA signatures. RC4 is
publicly known to have biases of several bits, which are likely
sufficient for a lattice solver to recover a ECDSA private key given a
number of signatures. One popular Bitcoin web wallet re-initialized
the RC4 state for every signature which makes the biases bit-aligned,
but in other cases the Special K would be manifest itself over
multiple transactions.
* identify and move all funds stored using SecureRandom()
* rotate all key material generated by, or has come into contact
with any piece of software using SecureRandom()
* do not write cryptographic tools in non-type safe languages
* don't take the output of a CSPRNG and pass it through RC4
-
3CJ99vSipFi9z11UdbdZWfNKjywJnY8sT8
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https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
<https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>
--
Matías Alejo Garcia
@ematiu
Roads? Where we're going, we don't need roads!
_______________________________________________
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Mustafa Al-Bassam via bitcoin-dev
2018-04-09 23:39:15 UTC
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The original disclosure didn't contain any information about the library
in question, so I did some digging.

I think that the vulnerability disclosure is referring to a pre-2013
version of jsbn, a JavaScript crypto library. Before it used the CSRNG
in the Web Crypto API, it tried to use nsIDOMCrypto, but incorrectly did
a string comparison when checking the browser version.

In practice though, this doesn't really matter, because
navigator.appVersion < "5" returns true anyway for old browsers. The
real issue is that modern browsers don't have window.crypto.random
defined, so Bitcoin wallets using a pre-2013 version of jsbn may not be
using a CSPRNG, when run on a modern browser.

As is noted though, even if a CSPRNG is used, the library passes the
output of the CSPRNG through RC4, which generates some biased bits,
leading to possible private key recovery.
Post by Mustafa Al-Bassam via bitcoin-dev
https://gist.github.com/jonls/5230850
Here's the code in question: https://github.com/jasondavies/jsbn/pull/7
Best,
Mustafa
Post by Matias Alejo Garcia via bitcoin-dev
Source?
On Fri, Apr 6, 2018 at 4:53 PM, ketamine--- via bitcoin-dev
A significant number of past and current cryptocurrency products
contain a JavaScript class named SecureRandom(), containing both
entropy collection and a PRNG. The entropy collection and the RNG
itself are both deficient to the degree that key material can be
recovered by a third party with medium complexity. There are a
substantial number of variations of this SecureRandom() class in
various pieces of software, some with bugs fixed, some with additional
bugs added. Products that aren't today vulnerable due to moving to
other libraries may be using old keys that have been previously
compromised by usage of SecureRandom().
The most common variations of the library attempts to collect entropy
from window.crypto's CSPRNG, but due to a type error in a comparison
this function is silently stepped over without failing. Entropy is
subsequently gathered from math.Random (a 48bit linear congruential
generator, seeded by the time in some browsers), and a single
execution of a medium resolution timer. In some known configurations
this system has substantially less than 48 bits of entropy.
The core of the RNG is an implementation of RC4 ("arcfour random"),
and the output is often directly used for the creation of private key
material as well as cryptographic nonces for ECDSA signatures. RC4 is
publicly known to have biases of several bits, which are likely
sufficient for a lattice solver to recover a ECDSA private key given a
number of signatures. One popular Bitcoin web wallet re-initialized
the RC4 state for every signature which makes the biases
bit-aligned,
but in other cases the Special K would be manifest itself over
multiple transactions.
* identify and move all funds stored using SecureRandom()
* rotate all key material generated by, or has come into contact
with any piece of software using SecureRandom()
* do not write cryptographic tools in non-type safe languages
* don't take the output of a CSPRNG and pass it through RC4
-
3CJ99vSipFi9z11UdbdZWfNKjywJnY8sT8
_______________________________________________
bitcoin-dev mailing list
https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
<https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>
--
Matías Alejo Garcia
@ematiu
Roads? Where we're going, we don't need roads!
_______________________________________________
bitcoin-dev mailing list
https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
_______________________________________________
bitcoin-dev mailing list
https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
Jason Davies via bitcoin-dev
2018-04-10 08:51:51 UTC
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Post by Mustafa Al-Bassam via bitcoin-dev
The original disclosure didn't contain any information about the library
in question, so I did some digging.
I think that the vulnerability disclosure is referring to a pre-2013
version of jsbn, a JavaScript crypto library. Before it used the CSRNG
in the Web Crypto API, it tried to use nsIDOMCrypto, but incorrectly did
a string comparison when checking the browser version.
In practice though, this doesn't really matter, because
navigator.appVersion < "5" returns true anyway for old browsers. The
real issue is that modern browsers don't have window.crypto.random
defined, so Bitcoin wallets using a pre-2013 version of jsbn may not be
using a CSPRNG, when run on a modern browser.
Yes, it looks like high-quality entropy via crypto.getRandomValues was only
added in Tom Wu's latest version (v1.4) in July 2013.

Note that even with v1.4, it still does not use high-quality entropy for
Internet Explorer, because getRandomValues is provided under window.msCrypto
for that browser.

http://www-cs-students.stanford.edu/~tjw/jsbn/rng.js
Post by Mustafa Al-Bassam via bitcoin-dev
As is noted though, even if a CSPRNG is used, the library passes the
output of the CSPRNG through RC4, which generates some biased bits,
leading to possible private key recovery.
I think this is the real issue: even if high-quality entropy is utilised, the
RNG is RC4-based, which is known to generate biased output.

Finally, note that even Chrome used RC4 for crypto.getRandomValues at one
point (as recently as 2015)!

https://bugs.chromium.org/p/chromium/issues/detail?id=552749

--
Jason Davies, https://www.jasondavies.com/
Aymeric Vitte via bitcoin-dev
2018-04-10 13:15:22 UTC
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I used jsbn in the past, then I made some research too

Apparently window.crypto.getRandomValues was introduced in jsbn mid 2012
(according to the wayback machine, but 2012/2013 does not make any
difference, see below), was available in Chrome since 2011 (but indeed
see "window.crypto.getRandomValues() uses a weak CSPRNG"
https://bugs.chromium.org/p/chromium/issues/detail?id=552749 fixed *end
*of 2015, funny to see that those that did specify the Webcrypto API did
not implement it correctly...), in FF in 2013
(https://website-archive.mozilla.org/www.mozilla.org/firefox_releasenotes/en-US/firefox/21.0/releasenotes/)
, in IE in 2013 and Safari ~2012/2013, at least that's the official
dates for the Webcrypto API implementation, maybe something existed
before, but it's not so easy to seek for the history

The window.crypto.random check is in jsbn since the begining (2006) and
only returns true for Netscape browsers before Netscape 5/6, ie Firefox
(2000), see
https://books.google.fr/books?id=UooAblGoGN8C&pg=PA85&lpg=PA85&dq=browser+appversion+4&source=bl&ots=dVijsOR0ov&sig=6SnElm56-bAvmGlKqUAdoGLAs2A&hl=fr&sa=X&ved=2ahUKEwirhtaqva_aAhUFchQKHQ4JCk4Q6AEwBXoECAAQcQ#v=onepage&q=browser%20appversion%204&f=false)

From the existing tools, there was not only jsbn, everybody was using
Math.random (sjcl, cryptoJS, forge, etc) with different implementations
and everybody did put a note stating that it might be insecure with an
"improvement to come" comment

We can probably assume that nobody was using Netscape any longer when
Bitcoin started

The conclusion seems to be that at least all wallets generated by js
tools inside browsers since bitcoin exists until 2011 are impacted by
the Math.random weakness if applicable to the related implementations,
the Math.random or RC4 (Chrome) weakness between 2011 and 2013, and RC4
weakness for Chrome users until end of 2015

And all wallets using jsbn are impacted by Math.random and RC4 until
2013 (or end 2015 for Chrome), then still by the RC4 fallback step after
Post by Jason Davies via bitcoin-dev
Note that even with v1.4, it still does not use high-quality entropy
for Internet Explorer, because getRandomValues is provided under
window.msCrypto for that browser

I don't know for that one, what was the issue?
Post by Jason Davies via bitcoin-dev
Post by Mustafa Al-Bassam via bitcoin-dev
The original disclosure didn't contain any information about the library
in question, so I did some digging.
I think that the vulnerability disclosure is referring to a pre-2013
version of jsbn, a JavaScript crypto library. Before it used the CSRNG
in the Web Crypto API, it tried to use nsIDOMCrypto, but incorrectly did
a string comparison when checking the browser version.
In practice though, this doesn't really matter, because
navigator.appVersion < "5" returns true anyway for old browsers. The
real issue is that modern browsers don't have window.crypto.random
defined, so Bitcoin wallets using a pre-2013 version of jsbn may not be
using a CSPRNG, when run on a modern browser.
Yes, it looks like high-quality entropy via crypto.getRandomValues was only
added in Tom Wu's latest version (v1.4) in July 2013.
Note that even with v1.4, it still does not use high-quality entropy for
Internet Explorer, because getRandomValues is provided under window.msCrypto
for that browser.
http://www-cs-students.stanford.edu/~tjw/jsbn/rng.js
Post by Mustafa Al-Bassam via bitcoin-dev
As is noted though, even if a CSPRNG is used, the library passes the
output of the CSPRNG through RC4, which generates some biased bits,
leading to possible private key recovery.
I think this is the real issue: even if high-quality entropy is utilised, the
RNG is RC4-based, which is known to generate biased output.
Finally, note that even Chrome used RC4 for crypto.getRandomValues at one
point (as recently as 2015)!
https://bugs.chromium.org/p/chromium/issues/detail?id=552749
--
Jason Davies, https://www.jasondavies.com/
_______________________________________________
bitcoin-dev mailing list
https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
--
Bitcoin transactions made simple: https://github.com/Ayms/bitcoin-transactions
Zcash wallets made simple: https://github.com/Ayms/zcash-wallets
Bitcoin wallets made simple: https://github.com/Ayms/bitcoin-wallets
Get the torrent dynamic blocklist: http://peersm.com/getblocklist
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Anti-spies and private torrents, dynamic blocklist: http://torrent-live.org
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torrent-live: https://github.com/Ayms/torrent-live
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GitHub : https://www.github.com/Ayms
Jason Davies via bitcoin-dev
2018-04-10 13:32:36 UTC
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Post by Aymeric Vitte via bitcoin-dev
Post by Jason Davies via bitcoin-dev
Note that even with v1.4, it still does not use high-quality entropy for
Internet Explorer, because getRandomValues is provided under window.msCrypto
for that browser.
I don't know for that one, what was the issue?
I simply meant that Internet Explorer implements the Web Cryptography API under
window.msCrypto instead of window.crypto. Thus, unless
msCrypto.getRandomValues is used, high-quality entropy will not have been used
by any of these libraries under Internet Explorer.

--
Jason Davies, https://www.jasondavies.com/
Aymeric Vitte via bitcoin-dev
2018-04-10 13:50:40 UTC
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Indeed, this impacts jsbn only normally since all others from the time
getRandomValues was available are supposed to implement both
Post by Jason Davies via bitcoin-dev
Post by Aymeric Vitte via bitcoin-dev
Post by Jason Davies via bitcoin-dev
Note that even with v1.4, it still does not use high-quality entropy for
Internet Explorer, because getRandomValues is provided under window.msCrypto
for that browser.
I don't know for that one, what was the issue?
I simply meant that Internet Explorer implements the Web Cryptography API under
window.msCrypto instead of window.crypto. Thus, unless
msCrypto.getRandomValues is used, high-quality entropy will not have been used
by any of these libraries under Internet Explorer.
--
Jason Davies, https://www.jasondavies.com/
--
Bitcoin transactions made simple: https://github.com/Ayms/bitcoin-transactions
Zcash wallets made simple: https://github.com/Ayms/zcash-wallets
Bitcoin wallets made simple: https://github.com/Ayms/bitcoin-wallets
Get the torrent dynamic blocklist: http://peersm.com/getblocklist
Check the 10 M passwords list: http://peersm.com/findmyass
Anti-spies and private torrents, dynamic blocklist: http://torrent-live.org
Peersm : http://www.peersm.com
torrent-live: https://github.com/Ayms/torrent-live
node-Tor : https://www.github.com/Ayms/node-Tor
GitHub : https://www.github.com/Ayms
Jason Davies via bitcoin-dev
2018-04-10 00:42:32 UTC
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These issues all stem from the RC4-based RNG implementation (with insecure
fallback entropy) in Tom Wu's jsbn library, published here:
http://www-cs-students.stanford.edu/~tjw/jsbn/

Please refer to Tom Wu's URL, or this more up-to-date fork of Tom Wu's code
(published to NPM): https://github.com/andyperlitch/jsbn -- my repository on
GitHub was only ever intended to be a straight mirror of Tom Wu's code (created
over 7 years ago!). I'll probably delete my mirror repository given that there
are now better JavaScript bignum alternatives, and in light of this report.

Jason
Here's the code in question: https://github.com/jasondavies/jsbn/pull/7
Best,
Mustafa
--
Jason Davies, http://www.jasondavies.com/
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