PuTTY 0.72 -- buffer overflow in SSH-1 and integer overflow in SSH client

Jul 20, 2019 06:00 pm Cyber Security 645

VuXML: PuTTY 0.72 -- buffer overflow in SSH-1 and integer overflow in SSH client

Details

VuXML ID
5914705c-ab03-11e9-a4f9-080027ac955c
Discovery
2019-07-14
Entry
2019-07-20

Simon Tatham reports:

Vulnerabilities fixed in this release include:

A malicious SSH-1 server could trigger a buffer overrun by sending extremely short RSA keys, or certain bad packet length fields. Either of these could happen before host key verification, so even if you trust the server you *intended* to connect to, you would still be at risk.(However, the SSH-1 protocol is obsolete, and recent versions of PuTTY do not try it by default, so you are only at risk if you work with old servers and have explicitly configured SSH-1.)

If a malicious process found a way to impersonate Pageant, then it could cause an integer overflow in any of the SSH client tools (PuTTY, Plink, PSCP, PSFTP) which accessed the malicious Pageant.

Other security-related bug fixes include:

The 'trust sigil' system introduced in PuTTY 0.71 to protect against server spoofing attacks had multiple bugs. Trust sigils were not turned off after login in the SSH-1 and Rlogin protocols, and not turned back on if you used the Restart Session command. Both are now fixed.