PUTTY SSH CLIENT FLAW ALLOWS RECOVERY OF CRYPTOGRAPHIC PRIVATE KEYS

Summary from the TLDR InfoSec newsletter

A vulnerability in PuTTY 0.68-0.80 could allow attackers with access to 60 cryptographic signatures from a user to compute the private keys offline. These signatures could come from an attacker-controlled SSH server or signed git commits. The vulnerability arises from the way that PuTTY generates ECDSA nonces, which lacks robust cryptographic random number generators on specific Windows versions.