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Message #79644
[Bug 1840288] Re: Trusts GET API leaks existence information to unauthorized users
I concur with the class C1 suggestion here. Generally OpenStack's VMT
has considered any theoretical vulnerability which depends on direct
brute-forcing or guessing the UUID space as impractical, but still
possibly a security hardening opportunity.
** Information type changed from Public Security to Public
** Changed in: ossa
Status: Incomplete => Won't Fix
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https://bugs.launchpad.net/bugs/1840288
Title:
Trusts GET API leaks existence information to unauthorized users
Status in OpenStack Identity (keystone):
In Progress
Status in OpenStack Security Advisory:
Won't Fix
Bug description:
The current implementation of the GET /v3/OS-TRUST/trusts/{trust_id}
API leaks information about the existence of a trust to unauthorized
users.
If an authenticated user requests a trust that either does not exist
or has no remaining uses, the returned response is a 404 regardless of
whether the user is an admin or a trustor/trustee of the hypothetical
(e.g. soft-deleted or used-up) trust. If the trust does exist but the
user has no access to it, the returned response is a 403. If an
attacker had some reasonable way of guessing or brute-forcing the UUID
of a trust, they could use this leak to confirm its existence. A valid
trust ID can then be used as part of a token request in combination
with the trustee's credentials.
The issue is here:
https://opendev.org/openstack/keystone/src/commit/5beddfaddbb4c59d7a24fa1d7ff534da4c69ddc5/keystone/api/trusts.py#L149-L150
The current "identity:get_trust" default policy rule is "" which is
all-permissive, and authorization is hardcoded in the trust controller
code. To enforce the "only the trustor or trustee can GET this" rule,
it does a lookup of the trust and doesn't catch a NotFound, thereby
leaking it directly back to the requester.
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References