CVE Vulnerabilities

CVE-2017-0884

Incorrect Permission Assignment for Critical Resource

Published: Apr 05, 2017 | Modified: Oct 04, 2022
CVSS 3.x
4.3
MEDIUM
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
CVSS 2.x
4 MEDIUM
AV:N/AC:L/Au:S/C:N/I:P/A:N
RedHat/V2
RedHat/V3
Ubuntu

Nextcloud Server before 9.0.55 and 10.0.2 suffers from a creation of folders in read-only folders despite lacking permissions issue. Due to a logical error in the file caching layer an authenticated adversary is able to create empty folders inside a shared folder. Note that this only affects folders and files that the adversary has at least read-only permissions for.

Weakness

The product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.

Affected Software

Name Vendor Start Version End Version
Nextcloud_server Nextcloud * 9.0.55 (excluding)
Nextcloud_server Nextcloud 10.0.0 (including) 10.0.2 (excluding)

Potential Mitigations

  • Run the code in a “jail” or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
  • OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
  • This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
  • Be careful to avoid CWE-243 and other weaknesses related to jails.

References