Autonomous collision attack on OCSP services

TL;DR

This paper identifies critical security flaws in OCSP that enable attackers to forge certificate statuses and certificates, compromising PKI trust, and discusses potential countermeasures.

Contribution

It reveals two major design flaws in OCSP, detailing how they can be exploited and proposing countermeasures to enhance protocol security.

Findings

Flaws allow forging of signed certificate statuses

Attackers can generate forged certificates

Security of OCSP is significantly weakened

Abstract

The paper describes two important design flaws in Online Certificate Status Protocol (OCSP), a protocol widely used in PKI environments for managing digital certificates' credibility in real time. The flaws significantly reduce the security capabilities of the protocol, and can be exploited by a malicious third party to generate forged signed certificate statuses and, in the worst scenario, forged certificates. Description of the flaws, along with expected exploitation routes, consequences for consuming application layer protocols, and proposed countermeasures, is given.