4 ms·

I kind of hate how browsers have pushed this centralized cert system and don't show self signed certs as valid.

by plopz 4y ago

seanw444 4y ago
It's both understandable, and frustrating, at the same time.
hedora 4y ago
From a threat model perspective, drawing the line where they have doesn't make much sense. If you can reliably intercept traffic between a host and the internet, then you can get Let's Encrypt (or any other ACME service) to issue a certificate for the host. If you cannot reliably intercept such traffic, then you can't reliably use a self signed certificate to intercept the traffic. So, the lock icon basically means "the coffee shop WiFi or your local puppet governement didn't spoof this connection, but AWS, a colo facility, the US/China/etc or a backbone provider may have". That's much weaker than most people realize. Edit: Because of this, an unpinned ACME certificate is actually weaker than a pinned self signed certificate for services that only have a few users.
- qpx 4y ago
  Would you mind to elaborate how A (the ability to intercept traffic) leads to B (the ability to make Let’s Encrypt issue a certificate for the (any?) host? I fail to see the connection
  - dolni 4y ago
    There is a blog post here that describes how to exploit it: https://www.mike-gualtieri.com/posts/chaining-remote-web-vulnerabilities-to-abuse-lets-encrypt https://www.mike-gualtieri.com/posts/chaining-remote-web-vul...
  - im3w1l 4y ago
    Let's Encrypt issues certs based on challenges. One challenge method is that they make an http request to the domain. If they get the correct response back then they will give you the cert. So what you would do is request a certificate, intercept the challenge, and answer correctly. Edit: If you did this, it would be show up in certificate transparency logs. So a very alert sysadmin could catch you in the act.
  - controversial97 4y ago
    I point to this recent case of a BGP hijack where an attacker got a certificate issued https://nitter.lacontrevoie.fr/rmhrisk/status/1574993338084003842#m https://nitter.lacontrevoie.fr/rmhrisk/status/15749933380840...
- iudqnolq 4y ago
  > So, the lock icon basically means "the coffee shop WiFi or your local puppet governement didn't spoof this connection, but AWS, a colo facility, the US/China/etc or a backbone provider may have". > That's much weaker than most people realize. Have you actually tested that? I bet you if you ask the average person "can your coffee shop read your emails" they'll say no, but if you ask "can the NSA read your emails" they'll say yes.

I kind of hate how browsers have pushed this centralized cert system and don't show self signed certs as valid.

by plopz 4y ago

I kind of hate how browsers have pushed this centralized cert system and don't show self signed certs as valid.

seanw444 4y ago

It's both understandable, and frustrating, at the same time.

hedora 4y ago

From a threat model perspective, drawing the line where they have doesn't make much sense. If you can reliably intercept traffic between a host and the internet, then you can get Let's Encrypt (or any other ACME service) to issue a certificate for the host. If you cannot reliably intercept such traffic, then you can't reliably use a self signed certificate to intercept the traffic. So, the lock icon basically means "the coffee shop WiFi or your local puppet governement didn't spoof this connection, but AWS, a colo facility, the US/China/etc or a backbone provider may have". That's much weaker than most people realize. Edit: Because of this, an unpinned ACME certificate is actually weaker than a pinned self signed certificate for services that only have a few users.

qpx 4y ago
Would you mind to elaborate how A (the ability to intercept traffic) leads to B (the ability to make Let’s Encrypt issue a certificate for the (any?) host? I fail to see the connection
- dolni 4y ago
  There is a blog post here that describes how to exploit it: https://www.mike-gualtieri.com/posts/chaining-remote-web-vulnerabilities-to-abuse-lets-encrypt https://www.mike-gualtieri.com/posts/chaining-remote-web-vul...
- im3w1l 4y ago
  Let's Encrypt issues certs based on challenges. One challenge method is that they make an http request to the domain. If they get the correct response back then they will give you the cert. So what you would do is request a certificate, intercept the challenge, and answer correctly. Edit: If you did this, it would be show up in certificate transparency logs. So a very alert sysadmin could catch you in the act.
- controversial97 4y ago
  I point to this recent case of a BGP hijack where an attacker got a certificate issued https://nitter.lacontrevoie.fr/rmhrisk/status/1574993338084003842#m https://nitter.lacontrevoie.fr/rmhrisk/status/15749933380840...
iudqnolq 4y ago
> So, the lock icon basically means "the coffee shop WiFi or your local puppet governement didn't spoof this connection, but AWS, a colo facility, the US/China/etc or a backbone provider may have". > That's much weaker than most people realize. Have you actually tested that? I bet you if you ask the average person "can your coffee shop read your emails" they'll say no, but if you ask "can the NSA read your emails" they'll say yes.