PuTTY -- fails to scrub private keys from memory after use

2015-02-28T00:00:00
ID 92FC2E2B-C383-11E4-8EF7-080027EF73EC
Type freebsd
Reporter FreeBSD
Modified 2015-02-28T00:00:00

Description

Simon Tatham reports:

When PuTTY has sensitive data in memory and has no further need for it, it should wipe the data out of its memory, in case malware later gains access to the PuTTY process or the memory is swapped out to disk or written into a crash dump file. An obvious example of this is the password typed during SSH login; other examples include obsolete session keys, public-key passphrases, and the private halves of public keys. PuTTY 0.63 and earlier versions, after loading a private key from a disk file, mistakenly leak a memory buffer containing a copy of the private key, in the function ssh2_load_userkey. The companion function ssh2_save_userkey (only called by PuTTYgen) can also leak a copy, but only in the case where the file it tried to save to could not be created.