Bug 1222871

Summary: VUL-0: CVE-2024-31497: filezilla: putty: NIST P521 private keys are exposed by biased signature generation
Product: [openSUSE] openSUSE Distribution Reporter: Marcus Meissner <meissner>
Component: SecurityAssignee: Eric Schirra <ecsos>
Status: IN_PROGRESS --- QA Contact: E-mail List <qa-bugs>
Severity: Normal    
Priority: P3 - Medium CC: Andreas.Stieger, jengelh, meissner, security-team
Version: Leap 15.5   
Target Milestone: ---   
Hardware: Other   
OS: Other   
URL: https://smash.suse.de/issue/401933/
Whiteboard:
Found By: --- Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---

Description Marcus Meissner 2024-04-16 07:21:59 UTC 
fork of the putty bug for the version embedded in filezilla.


+++ This bug was initially created as a clone of Bug #1222864 +++

In PuTTY 0.68 through 0.80 before 0.81, biased ECDSA nonce generation allows an attacker to recover a user's NIST P-521 secret key via a quick lattice-based attack in approximately 60 signatures. This is especially important in a scenario where an adversary is able to read messages signed by PuTTY or Pageant. One scenario is that the adversary is an operator of an SSH server to which the victim authenticates (for remote login or file copy), even though this server is not fully trusted by the victim, and the victim uses the same private key for SSH connections to other services operated by other entities. Here, the rogue server operator (who would otherwise have no way to determine the victim's private key) can derive the victim's private key, and then use it for unauthorized access to those other services. Because SSH is sometimes used to authenticate to Git services, it is possible that this vulnerability could be leveraged for supply-chain attacks on software maintained in Git. It is also conceivable that signed messages from PuTTY or Pageant are readable by adversaries more easily in other scenarios, but none have yet been disclosed. 

https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-p521-bias.html
https://www.openwall.com/lists/oss-security/2024/04/15/6
https://git.tartarus.org/?p=simon/putty.git;a=commitdiff;h=c193fe9848f50a88a4089aac647fecc31ae96d27
Comment 1 Eric Schirra 2024-04-16 07:45:01 UTC 
And what have an bug in putty to do with filezilla?
Think this a wrong place and should adressed to putty.
Comment 2 Jan Engelhardt 2024-04-16 07:47:33 UTC 
filezilla ships a bundled source code copy of putty, that's why.
Comment 3 Marcus Meissner 2024-04-16 07:48:04 UTC 
(In reply to Eric Schirra from comment #1)
> And what have an bug in putty to do with filezilla?
> Think this a wrong place and should adressed to putty.

Defined in package: network/filezilla 
  bugowner of filezilla : 
   -

  maintainer of filezilla : 
   ecsos@schirra.net


The issue is that filezilla has putty in src/putty/ as embedded library / code.

I would just wait that filezilla releases this as update.
Comment 4 Andreas Stieger 2024-04-16 15:42:38 UTC 
> 2024-04-15 - FileZilla Client 3.67.0 released
> SFTP: Fixed PuTTY ECDSA NIST P-521 private key recovery vulnerability (CVE-2024-31497). If you use NIST P-521 keys to connect to SSH/SFTP servers, you should regenerate them and revoke the previous ones.

Code fix for backporting:
https://svn.filezilla-project.org/filezilla?view=revision&revision=11142
Comment 5 Andreas Stieger 2024-04-17 13:25:15 UTC 
https://build.opensuse.org/request/show/1168540

Eric I'll see later (this week) how this could be brought into Leap...