Date: Tue, 17 Nov 2020 09:10:00 -0500 From: Ana McTaggart <amctagga@...hat.com> To: Ilya Dryomov <idryomov@...hat.com>, oss-security@...ts.openwall.com Subject: CVE-2020-25677 ceph: CEPHX_V2 replay attack protection lost Dear all, cephx authentication protocol does not verify ceph clients correctly, and is vulnerable to replay attacks in nautilus and later. An attacker with access to the Ceph cluster network can use this vulnerability to authenticate with ceph service, via a packet sniffer. This allows them to perform actions allowed by the ceph service. This is a reintroduction of CVE-2018-1128, affecting msgr2 protocol. msgr 2 protocol is used for all communication except for older clients that do not support msgr2 protocol. msgr1 protocol is not affected. This was introduced in commit to msgr2 321548010578 ("mon/MonClient: skip CEPHX_V2 challenge if client doesn't support it") , due to commit c58c5754dfd2 ("msg/async/ProtocolV1: use AuthServer and AuthClient") . This results in nautilus and ceph being affected because commit c58c5754dfd2 wasn't backported to nautilus, and although msgr1 isn't affected in nautilus, msgr 2 is the default. This made it so authorizer challenges could be skipped for peers which did not support CEPHX_V2, unfortunately making it so authorizer challenges are skipped for all peers in both msgr 1 and msgr2 cases, disabling the protection that was put in place in commit f80b848d3f83 ("auth/cephx: add authorizer challenge", CVE-2018-1128). Proposed Patch: See attached. We have assigned it a CVE of CVE-2020-25677 at Red Hat. Credits to Ilya Dryomov https://www.cvedetails.com/cve/CVE-2018-1128/ Ana McTaggart Red Hat Product Security Red Hat Remote <https://www.redhat.com> secalert@...hat.com for urgent response amct@...hat.com M: 7742790791 IM: amctagga Pronouns:They/Them/Theirs Content of type "text/html" skipped Download attachment "0003-mon-MonClient-bring-back-CEPHX_V2-authorizer-challen.patch" of type "application/x-patch" (3959 bytes) Download attachment "0001-msg-async-ProtocolV1-resurrect-include-MGR-as-servic.patch" of type "application/x-patch" (1505 bytes) Download attachment "0002-msg-async-ProtocolV1-resurrect-implement-cephx_-requ.patch" of type "application/x-patch" (2918 bytes)
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