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GHSA-3f99-hvg4-qjwj
No affected components available
Description and Impact
A bug in the pseudo-random number generator used by keypair versions up to and including 1.0.3 could allow for weak RSA key generation. This could enable an attacker to decrypt confidential messages or gain authorized access to an account belonging to the victim. We recommend replacing any RSA keys that were generated using keypair version 1.0.3 or earlier.
Fix
- The bug in the pseudo-random number generator is fixed in commit
9596418. - If the crypto module is available, it is used instead of the pseudo-random number generator. Also fixed in
9596418
Additional Details
The specific line with the flaw is:
b.putByte(String.fromCharCode(next & 0xFF))
The definition of putByte is
util.ByteBuffer.prototype.putByte = function(b) {
this.data += String.fromCharCode(b);
};
Simplified, this is String.fromCharCode(String.fromCharCode(next & 0xFF)). This results in most of the buffer containing zeros. An example generated buffer:
(Note: truncated for brevity)
\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
\x00\x00\x00\x00\x04\x00\x00\x00....\x00\x00\x00\x00\x00\x00\x00\x00\x00
\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
Since it is masking with 0xFF, approximately 97% of the bytes are converted to zeros. The impact is that each byte in the RNG seed has a 97% chance of being 0 due to incorrect conversion.
Credit
This issue was reported to GitHub Security Lab by Ross Wheeler of Axosoft. It was discovered by Axosoft engineer Dan Suceava, who noticed that keypair was regularly generating duplicate RSA keys. GitHub security engineer @vcsjones (Kevin Jones) independently investigated the problem and identified the cause and source code location of the bug.
The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data.
Exploitation activity has been observed. Apply available patches or mitigations urgently.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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