Access to all file-versions of a user as soon as he has one share with the attacker

Aug 10, 2020

Access to all file-versions of a user 

as soon as the user has one share with the attacker

Platform: ownCloud Server

Versions: 10.3.0,

Date: 2/28/2020

– Risk: Medium
– CVSS v3 Base Score: 6.8
– CVSS v3 Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
– CWE ID: 648
– CWE Name: Incorrect Use of Privileged APIs

An authenticated attacker can access all versions of all files (even unshared) as soon
as the owner of said files has at least one outgoing share with the attacker.

To attacker needs to guess a file-id which is numeric and sequential.

– owncloud/core >= v10.0.9
– owncloud/core < v10.3.1

Disable files_versions app by executing ‘occ app:disable files_versions’

Action taken
As the vulnerability is a result of incorrect usage of privileged APIs, all usages in owncloud-server of said
APIs are being reviewed and replaced with less privileged versions where necessary.

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