Researchers, at Ruhr University Bochum have uncovered a vulnerability in versions of the widely utilized PuTTY Secure Shell (SSH) client that could potentially allow malicious actors to retrieve private keys. This vulnerability, identified as CVE 2024 31497 affects PuTTY versions ranging from 0.68 to 0.80. Has also impacted projects that integrate susceptible PuTTY code.
As per the researchers findings the issue arises from the creation of nonces when utilizing the NIST P 521 Elliptic Curve Digital Signature Algorithm (ECDSA). Exploiting nonce generation could enable attackers to retrieve keys with just 60 signatures. Although gaining access to a server is necessary for this exploit it poses security risks, for any keys signed using versions of PuTTY Secure Shell.
How Widespread is The Putty Secure Shell Software?
Responsible disclosure has been carefully. All impacted projects have now issued updated versions, including PuTTY Secure Shell 0.81. Nevertheless it is advised to treat any keys used with the components as compromised. To prevent issues, in the future developers have integrated the RFC 6979 technique for nonce generation with ECDSA keys.
With its adoption due to being source and compatible across different platforms PuTTY Secure Shell boasts a large user base. It is widely utilized for managing servers and workstations. Additionally it is directly integrated into popular projects amplifying the potential impact of any vulnerabilities discovered. While fixes have been rolled out the key recovery attack serves as a reminder of the importance of staying vigilant, about security updates.