Thread: .deb signing key insecure against MitM
I just visited http://www.postgresql.org/download/linux/debian/ and my impression is that the way the signing key is published is not secured against wrong origin or manipulation by a man in the middle (MitM) attacker. Meaning, that if a MitM attacker can compromise downloads, he or she is also able to compromise the documentation site including the source of the signing key, e.g. by publishing the attacker's signing key to the user. Debian's apt-get will not complain if everything fits together. Therefore, I suggest that the whole page should be TLS secured (HTTPS-only), not because of encryption but to ensure origin and integrity of the signing key. It is not sufficient to have the signing key itself TLS-secured, because the documented hyperlink https://www.postgresql.org/media/keys/ACCC4CF8.asc could easily be manipulated by the MitM as well. I also suggest to go through the documentation to find similar occurences. Last, but not least, people might also tend to copy-paste some bash commands which offers additional possibilities for MitM to let users install malicious software with root permissions. In the long-run, I suggest to go for a HTTPS-only strategy with PostgreSQL's documentation (all of it). Related, but securing the download: http://www.postgresql.org/message-id/flat/1455875336.9107.60.camel@gunduz.org#1455875336.9107.60.camel@gunduz.org Note that the apt repository (including the downloadable packages) does not have to be TLS-secured as long as the package signing mechanism works well. Still, the additional security might not be harmful for most users. Best regards Thomas Mayer -- https://www.2bis10.de
On Mon, Mar 7, 2016 at 4:03 PM, Thomas Mayer <thomas.mayer@student.kit.edu> wrote:
I just visited http://www.postgresql.org/download/linux/debian/ and my impression is that the way the signing key is published is not secured against wrong origin or manipulation by a man in the middle (MitM) attacker.
Meaning, that if a MitM attacker can compromise downloads, he or she is also able to compromise the documentation site including the source of the signing key, e.g. by publishing the attacker's signing key to the user. Debian's apt-get will not complain if everything fits together.
Therefore, I suggest that the whole page should be TLS secured (HTTPS-only), not because of encryption but to ensure origin and integrity of the signing key.
Work is under way to make the entire website available under https only. It's blocked behind some other work at this point, but once we get there, it should make this situation a lot better.