On 12/14/12, Randy <nanog@afxr.net> wrote: [snip]
It explained that google is no longer accepting self signed ssl certificates. It claims that this change will "offer[s] a higher level of security to better protect your information".
Hm... Self-signed certificates, or (worse) the use of hostnames not on the certificate, are very common with POP/SMTP/IMAP over SSL/TLS servers; when setting up POP software, it is common that the user of an e-mail service will have instructions to check and install the certificate in the e-mail client, instead of requiring a unique IP address for every POP server mail domain, and a user purchased SSL certificate for each IP. The "major CAs" are not an authoritative list of CAs that may be used to sign POP, IMAP, or SMTP server certificates for various POP servers' on the internet; so Google's choices would seem poorly conceived in that regard. If Google should wish to enforce a validation of SSL certificates, the PKI authority required, should be specified by the user, not Google, or there should be a provision to accept any certificate whatsoever, by fingerprint, for a specific hostname; defined by the user. Google should go back to definitions. What is security: security is the assurance that the Confidentiality, Integrity, and Availability of data and systems are protected. How does this change apparently impact the assurances against risk? Availability: This change breaks availability, for users accessing servers already using self-signed certificates. (In other words, the change itself is a compromise of security; the risk that you lose availability of access to your mail that you expect to be downloaded via POP3 is 100%, if you have a self-signed cert in place) Confidentiality: The change prevents any transfer of data at all, unless the user of a self-signed certificate makes one of three changes: (1) Stop using gmail POP download altogether, in this case, confidentiality assurance may be improved, because no email can be downloaded and used with the service. In general, this may not be much of an improvement, when email has already been transmitted in cleartext, before it was placed on the remote POP server. (That might be their intended result -- discourage use of POP downloads) (2) Stop using SSL, and use regular POP3 instead. In this case, confidentiality will be no better than before, and may be significantly worse. A new risk of breach by 'passive sniffing' is created. When using SSL with a self-signed certificate; passive sniffing, or Deep packet inspection was not a risk: an active attack was a requirement. Therefore, being forced to "never use SSL", even without a CA signed cert, is not an improvement, and a potential increase in risk. (3) Users may buy an official certificate, from a 3rd party CA that Google trusts. In this case, the SSL encrypted POP3 connections from Google to the POP server, will have strong protection against possible exposure of data in transit due to active Man-in-the-middle attack. * In other words: If you deem Man-in-the-Middle attack more likely than Passive sniffing exposure attacks to discover users' passwords, and the majority of users' POP servers likely to have or get certificates from a CA that Google trusts, then forced rejection of any other certificates may be an improvement in assurance against these risks; forcing the remaining users to not use SSL, and risk their password being exposed is OK, because you deemed MITM the greater risk. If you do not make that assumption, then it is not clear at all, whether assurance of confidentiality has been improved or not; it may be improved slightly for some users, and terribly harmed for many others. Integrity: The change prevents any transfer of data at all, unless the user of a self-signed certificate makes one of three changes: (1) Stop using POP download altogether, in this case, data cannot be altered by an unauthorized user as it transits the network, data that wasn't downloaded couldn't have been tampered with. (2) Stop using SSL, and use regular POP3 instead. In this case, a new risk of "transparent inline tampering" is created, without encryption, a full blown MITM attack is not required, a passive interceptor can flip random bits, as long as they update the corresponding IP checksums; so there are new significant risks to integrity. (3) Users may buy an official certificate; in this case, the risk of interception by inline Man-in-the-middle attack is reduced.
I don't believe that this change offers better security. In fact it is now unsecured - I am unable to use ssl with gmail, I have had to select the plain-text pop3 option.
I don't have hundreds of dollars to get my ssl certificates signed, and to top it off, gmail never notified me of an error with fetching my
-- -JH