CVE Vulnerabilities

CVE-2021-21272

Improper Link Resolution Before File Access ('Link Following')

Published: Jan 25, 2021 | Modified: Oct 25, 2022
CVSS 3.x
7.7
HIGH
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N
CVSS 2.x
4 MEDIUM
AV:N/AC:L/Au:S/C:N/I:P/A:N
RedHat/V2
RedHat/V3
Ubuntu

ORAS is open source software which enables a way to push OCI Artifacts to OCI Conformant registries. ORAS is both a CLI for initial testing and a Go Module. In ORAS from version 0.4.0 and before version 0.9.0, there is a zip-slip vulnerability. The directory support feature allows the downloaded gzipped tarballs to be automatically extracted to the user-specified directory where the tarball can have symbolic links and hard links. A well-crafted tarball or tarballs allow malicious artifact providers linking, writing, or overwriting specific files on the host filesystem outside of the user-specified directory unexpectedly with the same permissions as the user who runs oras pull. Users of the affected versions are impacted if they are oras CLI users who runs oras pull, or if they are Go programs, which invoke github.com/deislabs/oras/pkg/content.FileStore. The problem has been fixed in version 0.9.0. For oras CLI users, there is no workarounds other than pulling from a trusted artifact provider. For oras package users, the workaround is to not use github.com/deislabs/oras/pkg/content.FileStore, and use other content stores instead, or pull from a trusted artifact provider.

Weakness

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Affected Software

Name Vendor Start Version End Version
Oras Deislabs 0.4.0 *

Potential Mitigations

  • Follow the principle of least privilege when assigning access rights to entities in a software system.
  • Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

References