Heartbleed: are services other than HTTPS affected?
The OpenSSL 'heartbleed' vulnerability (CVE-2014-0160) affects webservers serving HTTPS. Other services also use OpenSSL. Are these services also vulnerable to heartbleed-like data leakage?
I'm thinking in particular of
- sshd
- secure SMTP, IMAP etc -- dovecot, exim & postfix
- VPN servers -- openvpn and friends
all of which, on my systems at least, are linked to the OpenSSL libraries.
Any service that uses OpenSSL for its TLS implementation is potentially vulnerable; this is a weakness in the underlying cyrptography library, not in how it's presented via a web server or email server package. You should consider all linked services vulnerable to data leakage at least.
As I'm sure you're aware, it's quite possible to chain attacks together. Even in the simplest attacks it's perfectly possible to, for example, use Heartbleed to compromise SSL, read webmail credentials, use webmail credentials to gain access to other systems with a quick "Dear helpdesk, can you give me a new password for $foo, love CEO".
There's more information and links in The Heartbleed Bug, and in another question maintained by a Server Fault regular, Heartbleed: What is it and what are options to mitigate it?.
It seems your ssh-keys are safe:
It's worth pointing out that OpenSSH is not affected by the OpenSSL bug. While OpenSSH does use openssl for some key-generation functions, it does not use the TLS protocol (and in particular the TLS heartbeat extension that heartbleed attacks). So there is no need to worry about SSH being compromised, though it is still a good idea to update openssl to 1.0.1g or 1.0.2-beta2 (but you don't have to worry about replacing SSH keypairs). – dr jimbob 6 hours ago
See: https://security.stackexchange.com/questions/55076/what-should-one-do-about-the-heartbleed-openssl-exploit
In addition to the answer of @RobM, and since you ask about SMTP specifically: there already is a PoC for exploiting the bug on SMTP: https://gist.github.com/takeshixx/10107280