The Latacora firm has a blog post asserting that OpenSSH-portable has poor defaults for encrypting private RSA keys because of its reliance on OpenSSL. The blog goes into why this is a problem and how you can test it for yourself.
There is nothing wrong with the generated RSA keys themselves, however, just the encryption of the private RSA keys -- if made using current defaults. There are two ways of encrypting RSA keys, an old and apparently insecure way, and a new key format available but not default. Newer key types like Ed25519 use only the new key format and are not bothered by this problem.
Earlier on SN:
WikiLeaks Unveils CIA Implants That Steal SSH Credentials From Windows, Linux PCs (2017)
Upgrade Your SSH Keys (2016)
OpenSSH 6.8 Will Feature Key Discovery and Rotation for Easier Switching to DJB's Ed25519 (2015)
(Score: 2) by coolgopher on Tuesday August 07 2018, @01:44AM
Not when I'm just changing the passphrase (and storage format) on an existing key, no...