GHSA-r628-mhmh-qjhw

Suggest an improvement
Source
https://github.com/advisories/GHSA-r628-mhmh-qjhw
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/08/GHSA-r628-mhmh-qjhw/GHSA-r628-mhmh-qjhw.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-r628-mhmh-qjhw
Aliases
Published
2021-08-03T19:00:40Z
Modified
2023-11-08T04:06:00.466077Z
Severity
  • 8.2 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N CVSS Calculator
Summary
Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cache poisoning
Details

Impact

Arbitrary File Creation, Arbitrary File Overwrite, Arbitrary Code Execution

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 was insufficient when extracting tar files that contained both a directory and a symlink with the same name as the directory. This order of operations resulted 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 was thus 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, thus allowing arbitrary file creation and overwrite.

This issue was addressed in releases 3.2.3, 4.4.15, 5.0.7 and 6.1.2.

Patches

3.2.3 || 4.4.15 || 5.0.7 || 6.1.2

Workarounds

Users may work around this vulnerability without upgrading by creating a custom filter method which prevents the extraction of symbolic links.

const tar = require('tar')

tar.x({
  file: 'archive.tgz',
  filter: (file, entry) => {
    if (entry.type === 'SymbolicLink') {
      return false
    } else {
      return true
    }
  }
})

Users are encouraged to upgrade to the latest patch versions, rather than attempt to sanitize tar input themselves.

References

Affected packages

npm / tar

Package

Affected ranges

Type
SEMVER
Events
Introduced
3.0.0
Fixed
3.2.3

Ecosystem specific

{
    "affected_functions": [
        "(tar).Unpack"
    ]
}

npm / tar

Package

Affected ranges

Type
SEMVER
Events
Introduced
4.0.0
Fixed
4.4.15

Ecosystem specific

{
    "affected_functions": [
        "(tar).Unpack"
    ]
}

npm / tar

Package

Affected ranges

Type
SEMVER
Events
Introduced
5.0.0
Fixed
5.0.7

Ecosystem specific

{
    "affected_functions": [
        "(tar).Unpack"
    ]
}

npm / tar

Package

Affected ranges

Type
SEMVER
Events
Introduced
6.0.0
Fixed
6.1.2

Ecosystem specific

{
    "affected_functions": [
        "(tar).Unpack"
    ]
}