GHSA-QCX9-J53G-CCGF

Vulnerability from github – Published: 2021-08-05 17:01 – Updated: 2024-09-03 21:13
VLAI?
Summary
Remote Code Execution via unsafe classes in otherwise permitted modules
Details

Impact

The module AccessControl defines security policies for Python code used in restricted code within Zope applications. Restricted code is any code that resides in Zope's object database, such as the contents of Script (Python) objects.

The policies defined in AccessControl severely restrict access to Python modules and only exempt a few that are deemed safe, such as Python's string module. However, full access to the string module also allows access to the class Formatter, which can be overridden and extended within Script (Python) in a way that provides access to other unsafe Python libraries. Those unsafe Python libraries can be used for remote code execution.

By default, you need to have the admin-level Zope "Manager" role to add or edit Script (Python) objects through the web. Only sites that allow untrusted users to add/edit these scripts through the web - which would be a very unusual configuration to begin with - are at risk.

Patches

The problem has been fixed in AccessControl 4.3 and 5.2. Only AccessControl versions 4 and 5 are vulnerable, and only on Python 3, not Python 2.7.

Workarounds

A site administrator can restrict adding/editing Script (Python) objects through the web using the standard Zope user/role permission mechanisms. Untrusted users should not be assigned the Zope Manager role and adding/editing these scripts through the web should be restricted to trusted users only. This is the default configuration in Zope.

For more information

If you have any questions or comments about this advisory: * Open an issue in the AccessControl issue tracker * Email us at security@plone.org

Severity ?
4.4 (Medium)
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N
5.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "AccessControl"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0"
            },
            {
              "fixed": "4.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "AccessControl"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.0"
            },
            {
              "fixed": "5.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-32807"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321",
      "CWE-915"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-08-02T23:00:00Z",
    "nvd_published_at": "2021-07-30T22:15:00Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\nThe module `AccessControl` defines security policies for Python code used in restricted code within Zope applications. Restricted code is any code that resides in Zope\u0027s object database, such as the contents of `Script (Python)` objects. \n\nThe policies defined in `AccessControl` severely restrict access to Python modules and only exempt a few that are deemed safe, such as Python\u0027s `string` module. However, full access to the `string` module also allows access to the class `Formatter`, which can be overridden and extended within `Script (Python)` in a way that provides access to other unsafe Python libraries. Those unsafe Python libraries can be used for remote code execution.\n\nBy default, you need to have the admin-level Zope \"Manager\" role to add or edit `Script (Python)` objects through the web. Only sites that allow untrusted users to add/edit these scripts through the web - which would be a very unusual configuration to begin with - are at risk.\n\n### Patches\nThe problem has been fixed in AccessControl 4.3 and 5.2.\nOnly AccessControl versions 4 and 5 are vulnerable, and only on Python 3, not Python 2.7.\n\n### Workarounds\nA site administrator can restrict adding/editing `Script (Python)` objects through the web using the standard Zope user/role permission mechanisms. Untrusted users should not be assigned the Zope Manager role and adding/editing these scripts through the web should be restricted to trusted users only. This is the default configuration in Zope.\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in the [AccessControl issue tracker](https://github.com/zopefoundation/AccessControl/issues)\n* Email us at [security@plone.org](mailto:security@plone.org)\n",
  "id": "GHSA-qcx9-j53g-ccgf",
  "modified": "2024-09-03T21:13:35Z",
  "published": "2021-08-05T17:01:30Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/zopefoundation/AccessControl/security/advisories/GHSA-qcx9-j53g-ccgf"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zopefoundation/Zope/security/advisories/GHSA-g4gq-j4p2-j8fr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-32807"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zopefoundation/AccessControl/commit/ae2dab0cc34e6dd1561c5b12d4a56cd140f87e1d"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zopefoundation/AccessControl/commit/b42dd4badf803bb9fb71ac34cd9cb0c249262f2c"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zopefoundation/Zope/commit/869f947e586517566509e0ccdd4d99b60704cc02"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zopefoundation/Zope/commit/f72a18dda8e9bf2aedb46168761668464a4be988"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/accesscontrol/PYSEC-2021-335.yaml"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/accesscontrol/PYSEC-2021-370.yaml"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/zope/PYSEC-2021-368.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/zopefoundation/AccessControl"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zopefoundation/AccessControl/blob/master/CHANGES.rst#51-2021-07-30"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Remote Code Execution via unsafe classes in otherwise permitted modules"
}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.