Arbitrary File Overwrite

Affecting tar package, versions <3.2.3 || >=4.0.0 <4.4.15 || >=5.0.0 <5.0.7 || >=6.0.0 <6.1.2

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Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Arbitrary File Overwrite. This is due to insufficient symlink protection. node-tar aims to guarantee that any file whose location would be modified by a symbolic link is not extracted. This is, in part, achieved by ensuring that extracted directories are not symlinks. Additionally, in order to prevent unnecessary stat calls to determine whether a given path is a directory, paths are cached when directories are created.

This logic is insufficient when extracting tar files that contain both a directory and a symlink with the same name as the directory. This order of operations results in the directory being created and added to the node-tar directory cache. When a directory is present in the directory cache, subsequent calls to mkdir for that directory are skipped. However, this is also where node-tar checks for symlinks occur. By first creating a directory, and then replacing that directory with a symlink, it is possible to bypass node-tar symlink checks on directories, essentially allowing an untrusted tar file to symlink into an arbitrary location and subsequently extracting arbitrary files into that location.

Remediation

Upgrade tar to version 3.2.3, 4.4.15, 5.0.7, 6.1.2 or higher.

References

CVSS Score

8.2
high severity
  • Attack Vector
    Local
  • Attack Complexity
    Low
  • Privileges Required
    None
  • User Interaction
    Required
  • Scope
    Changed
  • Confidentiality
    High
  • Integrity
    High
  • Availability
    None
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Credit
ginkoid, chen-robert
CVE
CVE-2021-32803
CWE
CWE-22
Snyk ID
SNYK-JS-TAR-1536528
Disclosed
04 Aug, 2021
Published
04 Aug, 2021