On 10/07/2015 23:03, Jeffrey Walton wrote: >> During certificate verification, OpenSSL (starting from version 1.0.1n and >> 1.0.2b) will attempt to find an alternative certificate chain if the first >> attempt to build such a chain fails. An error in the implementation of this >> logic can mean that an attacker could cause certain checks on untrusted >> certificates to be bypassed, such as the CA flag, enabling them to use a >> valid >> leaf certificate to act as a CA and "issue" an invalid certificate. >> >> Why was this introduced in a patch release? I thought >> improved chain building was a new feature, and thus >> delineated by a library version number such as 1.0.2 or >> 1.0.3 . > I *think* "improved" chain building should have present in the library > earlier. The methods always exited. See, for example, 4158, > https://www.ietf.org/rfc/rfc4158.txt. > > Here's a real world failure due to previous, "naive" path building: > https://groups.google.com/d/msg/mailing.openssl.users/72_VQJmCmCU/hUMtemRNvRoJ. > The CA re-issued a root by changing the hash and serial number, but > recertifying the same public key and DN. Then, the server sent the old > root too as an intermediate. So there were two roots available, each > with the same DN. > >> In fact, I thought that was the reason we all >> had to wait ages before this long standing shortcoming >> was fixed. > It almost sound like you are complaining you did not have to wait ages :) It's the inconsistency of first insisting this cannot go into a patch and then pushing out a broken implementation inside a patch which was only supposed to fix security and build issues. This is the kind of event which has caused many dists to cherry pickindividual changes rather than just following the official releases. Enjoy Jakob -- Jakob Bohm, CIO, Partner, WiseMo A/S. http://www.wisemo.com Transformervej 29, 2860 S?borg, Denmark. Direct +45 31 13 16 10 This public discussion message is non-binding and may contain errors. WiseMo - Remote Service Management for PCs, Phones and Embedded
