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I patched up a Postfix + Dovecot server against a DROWN attack (I disabled sslv2 and sslv3).

https://test.drownattack.com

Shows :25
vulnerable to CVE-2016-0703
:110
vulnerable to CVE-2016-0703
...

Afterwards, if I connect with the command line OpenSSL's s_client using the -ssl2 switch then the protocol is not supported. Can I take this as a misdetection by their scanner?

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  • Also, unless I misunderstand: "[The test results] are based on data that is collected and processed in bulk, so they may be out of date and display services as vulnerable after the operators have mitigated the problem." which means it doesn't update in real time and if you can't reproduce the attack yourself the test result not updating isn't necessarily of concern.
    – user75753
    Mar 9, 2016 at 23:22
  • This tool shows vulnerable services detected in Feb. 2016 and probes each again to see if it’s been fixed. Results won't include new servers or ones our scanner missed. Live updates are cached for 15 minutes. I refreshed it many times yesterday and today too, their scanners seems to do some work but always comes back that the ports are vulnerable... with ssllabs.com you can clear the cache right away to initiate fresh rescan but it still showing me: 110 Yes Yes Vulnerable (same key with SSL v2)
    – defiler
    Mar 10, 2016 at 9:59

1 Answer 1

41

Port 110 is the default port for POP3, which historically is a clear text protocol but which has been extended to support STARTTLS to negotiate and upgrade to an encrypted connection over that clear text channel.

You would test that with the -starttls switch in openssl:

openssl s_client -starttls pop3 -connect host:110

Without using starttls to select the correct protocol to negotiate encryption openssl would not be able to detect any support for encryption and options like -ssl2 or -no_ssl2 would fail regardless.

The same holds true for port 25, but then with the smtp protocol ...

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