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http://www.scmagazine.com/researchers-detect-ssl-mitm-attacks-method-implemented-by-facebook/article/346994/ http://www.scmagazine.com/researchers-detect-ssl-mi

by cowbell 12y ago

http://www.scmagazine.com/researchers-detect-ssl-mitm-attacks-method-implemented-by-facebook/article/346994/ http://www.scmagazine.com/researchers-detect-ssl-mitm-attack... About 0.2% for Facebook is MITM. And they are not using self signed certificates.

yaur 12y ago
I'm going to go out on a limb here and say that the vast majority of that 0.2% are people sitting behind corporate proxies with a fake CA cert installed and pushed out to workstations via Group Policy. A hostile (and targeted) MITM could remove or alter the JavaScript that posts the fingerprint back to the server in which case it would be very difficult to detect. The problem with Self Signed Certs in a practical sense is that they enable a much broader range of attacks. Neither of them protect you from LEO and NSA. Neither of them protect you from the people that own and/or can run code on your PC. CA issued certs will protect you from the carder that is connected to the same public WiFi, but self signed certs wont.
- chimeracoder 12y ago
  > The problem with Self Signed Certs in a practical sense is that they enable a much broader range of attacks. Neither of them protect you from LEO and NSA. This phrasing is misleading. Self-signed certs will protect against passive attackers, assuming the certificate can be verified out-of-band[0]. If the validity of a self-signed certificate cannot be verified, yes, it could be issued by a MITM. But it still protects against passive attackers, and the NSA (so far) has predominantly been considered to be a passive attacker. Self-signed certificates are arguably more secure against LEO/NSA, because (again, assuming the validity of the cert can be verified), it is harder to MITM clients without the server admin finding out. With a CA, they can serve a subpoena to a third party (the CA) and force them to present a compromised certificate as "valid". For the LEO/NSA to masquerade as the legitimate server, it would have to subpoena the server administrator. [0] Which is always required with SSL. CA-issued certificates are also verified out-of-band, just indirectly (via the chain of trust).
  - YZF 12y ago
    The problem is that the people who can understand what you said don't ask questions about self signed certificates and the people who don't understand will somehow interpret this as support for using self signed certificates when you don't have an out-of-band method of getting your public key out. It's not harder to MITM a self signed cert when it's validty can't be verified which is 99.99% of the use cases where they're used...
    - chimeracoder 12y ago
      > It's not harder to MITM a self signed cert when it's validty can't be verified which is 99.99% of the use cases where they're used... No, but it's not easier, either - without verification, it's exactly the same. It's not meaningful to try and make SSL secure in the situation in which out-of-band verification cannot be done. If there is no out-of-band verification, all SSL fails to protect against MITM. At the very least, it protects against passive snooping (ie, the NSA).
      - yaur 12y ago
        WiFi attacks are not necessarily passive, ARP poisoning can redirect a victim's traffic to your machine at which point you can MITM to your hearts content. If you have trained your users to ignore the inevitable security warning (Grandma isn't going to check an SSL fingerprint) they are going to be operating under the false assumption that their communications are secure. For most people this is a worse scenario than the NSA having their data. If you are talking about a thick client, with the appropriate checks built in, I'll agree that it's possibly more secure. Other than that, its only possibly more secure if you are the only user or you can eliminate the security warning (e.g. by distributing the certificate). I'm skeptical that any US based company could get away with not rolling in the face of a subpoena/NSL so the protection provided by the service provider knowing they have been compromised is minimal IMO.
      - YZF 12y ago
        I see snooping as a lesser concern. For one thing the three letter agency snooping somewhere on the backbone can't even see the identity of the parties involved. They will typically see NATted IPs on both ends of some service provider. Once they decode the protocol they can get a little more information but at the end of the day the difference between knowing you established an SSL connection with respect to some static site and seeing the actual content of the page that you've viewed is IMO not a big difference. The bigger deal is the confusion it creates and the assumptions a lot of the users of self signed certs (and certs in general) make about security. Lastly I want to point out that if your certificate is signed by some external entity that doesn't prevent you from doing out-of-band management of your public key. As long as your private key is secret you never lose any security by having your cert signed by a third party. People can argue about how secure that signature is vs. those agencies who can force the third party to reveal their secret key but while that's an important consideration, until the government sells my banking information to somebody I mostly care about this at a principle level.

by cowbell 12y ago

yaur 12y ago

I'm going to go out on a limb here and say that the vast majority of that 0.2% are people sitting behind corporate proxies with a fake CA cert installed and pushed out to workstations via Group Policy. A hostile (and targeted) MITM could remove or alter the JavaScript that posts the fingerprint back to the server in which case it would be very difficult to detect. The problem with Self Signed Certs in a practical sense is that they enable a much broader range of attacks. Neither of them protect you from LEO and NSA. Neither of them protect you from the people that own and/or can run code on your PC. CA issued certs will protect you from the carder that is connected to the same public WiFi, but self signed certs wont.

chimeracoder 12y ago
> The problem with Self Signed Certs in a practical sense is that they enable a much broader range of attacks. Neither of them protect you from LEO and NSA. This phrasing is misleading. Self-signed certs will protect against passive attackers, assuming the certificate can be verified out-of-band[0]. If the validity of a self-signed certificate cannot be verified, yes, it could be issued by a MITM. But it still protects against passive attackers, and the NSA (so far) has predominantly been considered to be a passive attacker. Self-signed certificates are arguably more secure against LEO/NSA, because (again, assuming the validity of the cert can be verified), it is harder to MITM clients without the server admin finding out. With a CA, they can serve a subpoena to a third party (the CA) and force them to present a compromised certificate as "valid". For the LEO/NSA to masquerade as the legitimate server, it would have to subpoena the server administrator. [0] Which is always required with SSL. CA-issued certificates are also verified out-of-band, just indirectly (via the chain of trust).
- YZF 12y ago
  The problem is that the people who can understand what you said don't ask questions about self signed certificates and the people who don't understand will somehow interpret this as support for using self signed certificates when you don't have an out-of-band method of getting your public key out. It's not harder to MITM a self signed cert when it's validty can't be verified which is 99.99% of the use cases where they're used...
  - chimeracoder 12y ago
    > It's not harder to MITM a self signed cert when it's validty can't be verified which is 99.99% of the use cases where they're used... No, but it's not easier, either - without verification, it's exactly the same. It's not meaningful to try and make SSL secure in the situation in which out-of-band verification cannot be done. If there is no out-of-band verification, all SSL fails to protect against MITM. At the very least, it protects against passive snooping (ie, the NSA).
    - yaur 12y ago
      WiFi attacks are not necessarily passive, ARP poisoning can redirect a victim's traffic to your machine at which point you can MITM to your hearts content. If you have trained your users to ignore the inevitable security warning (Grandma isn't going to check an SSL fingerprint) they are going to be operating under the false assumption that their communications are secure. For most people this is a worse scenario than the NSA having their data. If you are talking about a thick client, with the appropriate checks built in, I'll agree that it's possibly more secure. Other than that, its only possibly more secure if you are the only user or you can eliminate the security warning (e.g. by distributing the certificate). I'm skeptical that any US based company could get away with not rolling in the face of a subpoena/NSL so the protection provided by the service provider knowing they have been compromised is minimal IMO.
    - YZF 12y ago
      I see snooping as a lesser concern. For one thing the three letter agency snooping somewhere on the backbone can't even see the identity of the parties involved. They will typically see NATted IPs on both ends of some service provider. Once they decode the protocol they can get a little more information but at the end of the day the difference between knowing you established an SSL connection with respect to some static site and seeing the actual content of the page that you've viewed is IMO not a big difference. The bigger deal is the confusion it creates and the assumptions a lot of the users of self signed certs (and certs in general) make about security. Lastly I want to point out that if your certificate is signed by some external entity that doesn't prevent you from doing out-of-band management of your public key. As long as your private key is secret you never lose any security by having your cert signed by a third party. People can argue about how secure that signature is vs. those agencies who can force the third party to reveal their secret key but while that's an important consideration, until the government sells my banking information to somebody I mostly care about this at a principle level.