By r0gu3Sec | October 25, 2016 - 15:41 | Posted in CyberGuerrilla | 1 Comment
Let’s Encrypt’s Vulnerability

Let’s Encrypt’s Vulnerability As a Feature – AUTHZ Reuse and Eternal Account Key

The growth of Let’s Encrypt is phenomenal 7 million certificates in last four months.

The remaining hurdle for automation is verification of domain ownership. Well, actually it is NOT true.

We were doing syntax testing – hoping to get the right kind of verification error … only to discover we have been successfully verified without providing any information.

Wle-certs-issued-june-22-2016hatever you say about let’s encrypt project, you can’t deny its success.

Issuance of certificates has been commoditized for a while and definitely ripe for disruption.

Let’s Encrypt is the disruption and its adoption, despite shorter validity of certificates issued by Let’s Encrypt CA, is exponential and really fast.

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One Response to Let’s Encrypt’s Vulnerability

  1. As of last Thursday the validity is now 60 days! Goal is to eventually reduce this towards 7 days. Using cached domain authorization for issuance isn’t specific to Let’s Encrypt. Other CAs do this as well but with less visibility/control into the mechanics.

    You could issue a new certificate using an existing valid authz w/o solving a challenge before this feature existed. The reuse feature only addressed cases where the client asked for a new authz/challenge for a domain even though there already was a valid authz for that domain associated with the account. It was an optimization and did not change any security properties of the protocol or domain validation.