YubiKey-maker Yubico issued an advisory in coordination with a detailed disclosure report from NinjaLab, the security firm that reverse-engineered the YubiKey 5 series and devised the cloning attack. All YubiKeys running firmware prior to version 5.7—which was released in May and replaces the Infineon cryptolibrary with a custom one—are vulnerable. Updating key firmware on the YubiKey isn’t possible. That leaves all affected YubiKeys permanently vulnerable. “An attacker could exploit this issue as part of a sophisticated and targeted attack to recover affected private keys,” the advisory confirmed. “The attacker would need physical possession of the YubiKey, Security Key, or YubiHSM, knowledge of the accounts they want to target, and specialized equipment to perform the necessary attack. Depending on the use case, the attacker may also require additional knowledge including username, PIN, account password, or authentication key.”
https://mastodon.sdf.org/system/media_attachments/files/113/075/601/209/906/369/original/4fef65f38156af26.png