segunda-feira, 20 de março de 2017

Falha de Segurança no Telnet em Switches Cisco Catalyst

Olá Pessoal,

Em 17/03/2017 pp. a Cisco anunciou uma vulnerabilidade de segurança em vários switches da família Catalyst que foi descoberta a partir do vazamento recém apelidado de Vault 7, oportunidade em que mais de 8000 documentos e arquivos foram vazados no Wikileaks com detalhes de táticas e ferramentas de hacking  utilizados pela Agência Central de Inteligência (CIA) dos EUA.

O bug em questão afeta 264 switches Catalyst, 51 switches industriais Ethernet e outros 3 dispositivos, caso eles estejam executando o IOS e configurados para aceitar conexões Telnet que, convenhamos, já não deveria mais ser utilizado como protocolo de acesso remoto há anos. Segundo a Cisco, a falha estaria relacionada ao Cluster Management Protocol (CMP) no código do IOS que utiliza o Telnet internamente como protocolo de sinalização. A vulnerabilidade é que um atacante poderia explorar esse protocolo enviando opções Telnet deformadas do CMP para ganhar acesso remoto ao dispositivo e executar comandos privilegiados sem necessidade de efetuar qualquer autenticação.


Abaixo trago uma relação de todos os equipamentos afetados pela falha de segurança:

  • Cisco Catalyst 2350-48TD-S Switch
  • Cisco Catalyst 2350-48TD-SD Switch
  • Cisco Catalyst 2360-48TD-S Switch
  • Cisco Catalyst 2918-24TC-C Switch
  • Cisco Catalyst 2918-24TT-C Switch
  • Cisco Catalyst 2918-48TC-C Switch
  • Cisco Catalyst 2918-48TT-C Switch
  • Cisco Catalyst 2928-24TC-C Switch
  • Cisco Catalyst 2960-24-S Switch
  • Cisco Catalyst 2960-24LC-S Switch
  • Cisco Catalyst 2960-24LT-L Switch
  • Cisco Catalyst 2960-24PC-L Switch
  • Cisco Catalyst 2960-24PC-S Switch
  • Cisco Catalyst 2960-24TC-L Switch
  • Cisco Catalyst 2960-24TC-S Switch
  • Cisco Catalyst 2960-24TT-L Switch
  • Cisco Catalyst 2960-48PST-L Switch
  • Cisco Catalyst 2960-48PST-S Switch
  • Cisco Catalyst 2960-48TC-L Switch
  • Cisco Catalyst 2960-48TC-S Switch
  • Cisco Catalyst 2960-48TT-L Switch
  • Cisco Catalyst 2960-48TT-S Switch
  • Cisco Catalyst 2960-8TC-L Compact Switch
  • Cisco Catalyst 2960-8TC-S Compact Switch
  • Cisco Catalyst 2960-Plus 24LC-L Switch
  • Cisco Catalyst 2960-Plus 24LC-S Switch
  • Cisco Catalyst 2960-Plus 24PC-L Switch
  • Cisco Catalyst 2960-Plus 24PC-S Switch
  • Cisco Catalyst 2960-Plus 24TC-L Switch
  • Cisco Catalyst 2960-Plus 24TC-S Switch
  • Cisco Catalyst 2960-Plus 48PST-L Switch
  • Cisco Catalyst 2960-Plus 48PST-S Switch
  • Cisco Catalyst 2960-Plus 48TC-L Switch
  • Cisco Catalyst 2960-Plus 48TC-S Switch
  • Cisco Catalyst 2960C-12PC-L Switch
  • Cisco Catalyst 2960C-8PC-L Switch
  • Cisco Catalyst 2960C-8TC-L Switch
  • Cisco Catalyst 2960C-8TC-S Switch
  • Cisco Catalyst 2960CG-8TC-L Compact Switch
  • Cisco Catalyst 2960CPD-8PT-L Switch
  • Cisco Catalyst 2960CPD-8TT-L Switch
  • Cisco Catalyst 2960CX-8PC-L Switch
  • Cisco Catalyst 2960CX-8TC-L Switch
  • Cisco Catalyst 2960G-24TC-L Switch
  • Cisco Catalyst 2960G-48TC-L Switch
  • Cisco Catalyst 2960G-8TC-L Compact Switch
  • Cisco Catalyst 2960L-16PS-LL Switch
  • Cisco Catalyst 2960L-16TS-LL Switch
  • Cisco Catalyst 2960L-24PS-LL Switch
  • Cisco Catalyst 2960L-24TS-LL Switch
  • Cisco Catalyst 2960L-48PS-LL Switch
  • Cisco Catalyst 2960L-48TS-LL Switch
  • Cisco Catalyst 2960L-8PS-LL Switch
  • Cisco Catalyst 2960L-8TS-LL Switch
  • Cisco Catalyst 2960PD-8TT-L Compact Switch
  • Cisco Catalyst 2960S-24PD-L Switch
  • Cisco Catalyst 2960S-24PS-L Switch
  • Cisco Catalyst 2960S-24TD-L Switch
  • Cisco Catalyst 2960S-24TS-L Switch
  • Cisco Catalyst 2960S-24TS-S Switch
  • Cisco Catalyst 2960S-48FPD-L Switch
  • Cisco Catalyst 2960S-48FPS-L Switch
  • Cisco Catalyst 2960S-48LPD-L Switch
  • Cisco Catalyst 2960S-48LPS-L Switch
  • Cisco Catalyst 2960S-48TD-L Switch
  • Cisco Catalyst 2960S-48TS-L Switch
  • Cisco Catalyst 2960S-48TS-S Switch
  • Cisco Catalyst 2960S-F24PS-L Switch
  • Cisco Catalyst 2960S-F24TS-L Switch
  • Cisco Catalyst 2960S-F24TS-S Switch
  • Cisco Catalyst 2960S-F48FPS-L Switch
  • Cisco Catalyst 2960S-F48LPS-L Switch
  • Cisco Catalyst 2960S-F48TS-L Switch
  • Cisco Catalyst 2960S-F48TS-S Switch
  • Cisco Catalyst 2960X-24PD-L Switch
  • Cisco Catalyst 2960X-24PS-L Switch
  • Cisco Catalyst 2960X-24PSQ-L Cool Switch
  • Cisco Catalyst 2960X-24TD-L Switch
  • Cisco Catalyst 2960X-24TS-L Switch
  • Cisco Catalyst 2960X-24TS-LL Switch
  • Cisco Catalyst 2960X-48FPD-L Switch
  • Cisco Catalyst 2960X-48FPS-L Switch
  • Cisco Catalyst 2960X-48LPD-L Switch
  • Cisco Catalyst 2960X-48LPS-L Switch
  • Cisco Catalyst 2960X-48TD-L Switch
  • Cisco Catalyst 2960X-48TS-L Switch
  • Cisco Catalyst 2960X-48TS-LL Switch
  • Cisco Catalyst 2960XR-24PD-I Switch
  • Cisco Catalyst 2960XR-24PD-L Switch
  • Cisco Catalyst 2960XR-24PS-I Switch
  • Cisco Catalyst 2960XR-24PS-L Switch
  • Cisco Catalyst 2960XR-24TD-I Switch
  • Cisco Catalyst 2960XR-24TD-L Switch
  • Cisco Catalyst 2960XR-24TS-I Switch
  • Cisco Catalyst 2960XR-24TS-L Switch
  • Cisco Catalyst 2960XR-48FPD-I Switch
  • Cisco Catalyst 2960XR-48FPD-L Switch
  • Cisco Catalyst 2960XR-48FPS-I Switch
  • Cisco Catalyst 2960XR-48FPS-L Switch
  • Cisco Catalyst 2960XR-48LPD-I Switch
  • Cisco Catalyst 2960XR-48LPD-L Switch
  • Cisco Catalyst 2960XR-48LPS-I Switch
  • Cisco Catalyst 2960XR-48LPS-L Switch
  • Cisco Catalyst 2960XR-48TD-I Switch
  • Cisco Catalyst 2960XR-48TD-L Switch
  • Cisco Catalyst 2960XR-48TS-I Switch
  • Cisco Catalyst 2960XR-48TS-L Switch
  • Cisco Catalyst 2970G-24T Switch
  • Cisco Catalyst 2970G-24TS Switch
  • Cisco Catalyst 2975 Switch
  • Cisco Catalyst 3550 12G Switch
  • Cisco Catalyst 3550 12T Switch
  • Cisco Catalyst 3550 24 DC SMI Switch
  • Cisco Catalyst 3550 24 EMI Switch
  • Cisco Catalyst 3550 24 FX SMI Switch
  • Cisco Catalyst 3550 24 PWR Switch
  • Cisco Catalyst 3550 24 SMI Switch
  • Cisco Catalyst 3550 48 EMI Switch
  • Cisco Catalyst 3550 48 SMI Switch
  • Cisco Catalyst 3560-12PC-S Compact Switch
  • Cisco Catalyst 3560-24PS Switch
  • Cisco Catalyst 3560-24TS Switch
  • Cisco Catalyst 3560-48PS Switch
  • Cisco Catalyst 3560-48TS Switch
  • Cisco Catalyst 3560-8PC Compact Switch
  • Cisco Catalyst 3560C-12PC-S Switch
  • Cisco Catalyst 3560C-8PC-S Switch
  • Cisco Catalyst 3560CG-8PC-S Compact Switch
  • Cisco Catalyst 3560CG-8TC-S Compact Switch
  • Cisco Catalyst 3560CPD-8PT-S Compact Switch
  • Cisco Catalyst 3560CX-12PC-S Switch
  • Cisco Catalyst 3560CX-12PD-S Switch
  • Cisco Catalyst 3560CX-12TC-S Switch
  • Cisco Catalyst 3560CX-8PC-S Switch
  • Cisco Catalyst 3560CX-8PT-S Switch
  • Cisco Catalyst 3560CX-8TC-S Switch
  • Cisco Catalyst 3560CX-8XPD-S Switch
  • Cisco Catalyst 3560E-12D-E Switch
  • Cisco Catalyst 3560E-12D-S Switch
  • Cisco Catalyst 3560E-12SD-E Switch
  • Cisco Catalyst 3560E-12SD-S Switch
  • Cisco Catalyst 3560E-24PD-E Switch
  • Cisco Catalyst 3560E-24PD-S Switch
  • Cisco Catalyst 3560E-24TD-E Switch
  • Cisco Catalyst 3560E-24TD-S Switch
  • Cisco Catalyst 3560E-48PD-E Switch
  • Cisco Catalyst 3560E-48PD-EF Switch
  • Cisco Catalyst 3560E-48PD-S Switch
  • Cisco Catalyst 3560E-48PD-SF Switch
  • Cisco Catalyst 3560E-48TD-E Switch
  • Cisco Catalyst 3560E-48TD-S Switch
  • Cisco Catalyst 3560G-24PS Switch
  • Cisco Catalyst 3560G-24TS Switch
  • Cisco Catalyst 3560G-48PS Switch
  • Cisco Catalyst 3560G-48TS Switch
  • Cisco Catalyst 3560V2-24DC Switch
  • Cisco Catalyst 3560V2-24PS Switch
  • Cisco Catalyst 3560V2-24TS Switch
  • Cisco Catalyst 3560V2-48PS Switch
  • Cisco Catalyst 3560V2-48TS Switch
  • Cisco Catalyst 3560X-24P-E Switch
  • Cisco Catalyst 3560X-24P-L Switch
  • Cisco Catalyst 3560X-24P-S Switch
  • Cisco Catalyst 3560X-24T-E Switch
  • Cisco Catalyst 3560X-24T-L Switch
  • Cisco Catalyst 3560X-24T-S Switch
  • Cisco Catalyst 3560X-24U-E Switch
  • Cisco Catalyst 3560X-24U-L Switch
  • Cisco Catalyst 3560X-24U-S Switch
  • Cisco Catalyst 3560X-48P-E Switch
  • Cisco Catalyst 3560X-48P-L Switch
  • Cisco Catalyst 3560X-48P-S Switch
  • Cisco Catalyst 3560X-48PF-E Switch
  • Cisco Catalyst 3560X-48PF-L Switch
  • Cisco Catalyst 3560X-48PF-S Switch
  • Cisco Catalyst 3560X-48T-E Switch
  • Cisco Catalyst 3560X-48T-L Switch
  • Cisco Catalyst 3560X-48T-S Switch
  • Cisco Catalyst 3560X-48U-E Switch
  • Cisco Catalyst 3560X-48U-L Switch
  • Cisco Catalyst 3560X-48U-S Switch
  • Cisco Catalyst 3750 Metro 24-AC Switch
  • Cisco Catalyst 3750 Metro 24-DC Switch
  • Cisco Catalyst 3750-24FS Switch
  • Cisco Catalyst 3750-24PS Switch
  • Cisco Catalyst 3750-24TS Switch
  • Cisco Catalyst 3750-48PS Switch
  • Cisco Catalyst 3750-48TS Switch
  • Cisco Catalyst 3750E-24PD-E Switch
  • Cisco Catalyst 3750E-24PD-S Switch
  • Cisco Catalyst 3750E-24TD-E Switch
  • Cisco Catalyst 3750E-24TD-S Switch
  • Cisco Catalyst 3750E-48PD-E Switch
  • Cisco Catalyst 3750E-48PD-EF Switch
  • Cisco Catalyst 3750E-48PD-S Switch
  • Cisco Catalyst 3750E-48PD-SF Switch
  • Cisco Catalyst 3750E-48TD-E Switch
  • Cisco Catalyst 3750E-48TD-S Switch
  • Cisco Catalyst 3750G-12S Switch
  • Cisco Catalyst 3750G-12S-SD Switch
  • Cisco Catalyst 3750G-16TD Switch
  • Cisco Catalyst 3750G-24PS Switch
  • Cisco Catalyst 3750G-24T Switch
  • Cisco Catalyst 3750G-24TS Switch
  • Cisco Catalyst 3750G-24TS-1U Switch
  • Cisco Catalyst 3750G-48PS Switch
  • Cisco Catalyst 3750G-48TS Switch
  • Cisco Catalyst 3750V2-24FS Switch
  • Cisco Catalyst 3750V2-24PS Switch
  • Cisco Catalyst 3750V2-24TS Switch
  • Cisco Catalyst 3750V2-48PS Switch
  • Cisco Catalyst 3750V2-48TS Switch
  • Cisco Catalyst 3750X-12S-E Switch
  • Cisco Catalyst 3750X-12S-S Switch
  • Cisco Catalyst 3750X-24P-E Switch
  • Cisco Catalyst 3750X-24P-L Switch
  • Cisco Catalyst 3750X-24P-S Switch
  • Cisco Catalyst 3750X-24S-E Switch
  • Cisco Catalyst 3750X-24S-S Switch
  • Cisco Catalyst 3750X-24T-E Switch
  • Cisco Catalyst 3750X-24T-L Switch
  • Cisco Catalyst 3750X-24T-S Switch
  • Cisco Catalyst 3750X-24U-E Switch
  • Cisco Catalyst 3750X-24U-L Switch
  • Cisco Catalyst 3750X-24U-S Switch
  • Cisco Catalyst 3750X-48P-E Switch
  • Cisco Catalyst 3750X-48P-L Switch
  • Cisco Catalyst 3750X-48P-S Switch
  • Cisco Catalyst 3750X-48PF-E Switch
  • Cisco Catalyst 3750X-48PF-L Switch
  • Cisco Catalyst 3750X-48PF-S Switch
  • Cisco Catalyst 3750X-48T-E Switch
  • Cisco Catalyst 3750X-48T-L Switch
  • Cisco Catalyst 3750X-48T-S Switch
  • Cisco Catalyst 3750X-48U-E Switch
  • Cisco Catalyst 3750X-48U-L Switch
  • Cisco Catalyst 3750X-48U-S Switch
  • Cisco Catalyst 4000 Supervisor Engine I
  • Cisco Catalyst 4000/4500 Supervisor Engine IV
  • Cisco Catalyst 4000/4500 Supervisor Engine V
  • Cisco Catalyst 4500 Series Supervisor Engine II-Plus
  • Cisco Catalyst 4500 Series Supervisor Engine II-Plus-TS
  • Cisco Catalyst 4500 Series Supervisor Engine V-10GE
  • Cisco Catalyst 4500 Series Supervisor II-Plus-10GE
  • Cisco Catalyst 4500 Supervisor Engine 6-E
  • Cisco Catalyst 4500 Supervisor Engine 6L-E
  • Cisco Catalyst 4900M Switch
  • Cisco Catalyst 4928 10 Gigabit Ethernet Switch
  • Cisco Catalyst 4948 10 Gigabit Ethernet Switch
  • Cisco Catalyst 4948 Switch
  • Cisco Catalyst 4948E Ethernet Switch
  • Cisco Catalyst 4948E-F Ethernet Switch
  • Cisco Catalyst Blade Switch 3020 for HP
  • Cisco Catalyst Blade Switch 3030 for Dell
  • Cisco Catalyst Blade Switch 3032 for Dell M1000E
  • Cisco Catalyst Blade Switch 3040 for FSC
  • Cisco Catalyst Blade Switch 3120 for HP
  • Cisco Catalyst Blade Switch 3120X for HP
  • Cisco Catalyst Blade Switch 3130 for Dell M1000E
  • Cisco Catalyst C2928-24LT-C Switch
  • Cisco Catalyst C2928-48TC-C Switch
  • Cisco Catalyst Switch Module 3012 for IBM BladeCenter
  • Cisco Catalyst Switch Module 3110 for IBM BladeCenter
  • Cisco Catalyst Switch Module 3110X for IBM BladeCenter
  • Cisco Embedded Service 2020 24TC CON B Switch
  • Cisco Embedded Service 2020 24TC CON Switch
  • Cisco Embedded Service 2020 24TC NCP B Switch
  • Cisco Embedded Service 2020 24TC NCP Switch
  • Cisco Embedded Service 2020 CON B Switch
  • Cisco Embedded Service 2020 CON Switch
  • Cisco Embedded Service 2020 NCP B Switch
  • Cisco Embedded Service 2020 NCP Switch
  • Cisco Enhanced Layer 2 EtherSwitch Service Module
  • Cisco Enhanced Layer 2/3 EtherSwitch Service Module
  • Cisco Gigabit Ethernet Switch Module (CGESM) for HP
  • Cisco IE 2000-16PTC-G Industrial Ethernet Switch
  • Cisco IE 2000-16T67 Industrial Ethernet Switch
  • Cisco IE 2000-16T67P Industrial Ethernet Switch
  • Cisco IE 2000-16TC Industrial Ethernet Switch
  • Cisco IE 2000-16TC-G Industrial Ethernet Switch
  • Cisco IE 2000-16TC-G-E Industrial Ethernet Switch
  • Cisco IE 2000-16TC-G-N Industrial Ethernet Switch
  • Cisco IE 2000-16TC-G-X Industrial Ethernet Switch
  • Cisco IE 2000-24T67 Industrial Ethernet Switch
  • Cisco IE 2000-4S-TS-G Industrial Ethernet Switch
  • Cisco IE 2000-4T Industrial Ethernet Switch
  • Cisco IE 2000-4T-G Industrial Ethernet Switch
  • Cisco IE 2000-4TS Industrial Ethernet Switch
  • Cisco IE 2000-4TS-G Industrial Ethernet Switch
  • Cisco IE 2000-8T67 Industrial Ethernet Switch
  • Cisco IE 2000-8T67P Industrial Ethernet Switch
  • Cisco IE 2000-8TC Industrial Ethernet Switch
  • Cisco IE 2000-8TC-G Industrial Ethernet Switch
  • Cisco IE 2000-8TC-G-E Industrial Ethernet Switch
  • Cisco IE 2000-8TC-G-N Industrial Ethernet Switch
  • Cisco IE 3000-4TC Industrial Ethernet Switch
  • Cisco IE 3000-8TC Industrial Ethernet Switch
  • Cisco IE-3010-16S-8PC Industrial Ethernet Switch
  • Cisco IE-3010-24TC Industrial Ethernet Switch
  • Cisco IE-4000-16GT4G-E Industrial Ethernet Switch
  • Cisco IE-4000-16T4G-E Industrial Ethernet Switch
  • Cisco IE-4000-4GC4GP4G-E Industrial Ethernet Switch
  • Cisco IE-4000-4GS8GP4G-E Industrial Ethernet Switch
  • Cisco IE-4000-4S8P4G-E Industrial Ethernet Switch
  • Cisco IE-4000-4T4P4G-E Industrial Ethernet Switch
  • Cisco IE-4000-4TC4G-E Industrial Ethernet Switch
  • Cisco IE-4000-8GS4G-E Industrial Ethernet Switch
  • Cisco IE-4000-8GT4G-E Industrial Ethernet Switch
  • Cisco IE-4000-8GT8GP4G-E Industrial Ethernet Switch
  • Cisco IE-4000-8S4G-E Industrial Ethernet Switch
  • Cisco IE-4000-8T4G-E Industrial Ethernet Switch
  • Cisco IE-4010-16S12P Industrial Ethernet Switch
  • Cisco IE-4010-4S24P Industrial Ethernet Switch
  • Cisco IE-5000-12S12P-10G Industrial Ethernet Switch
  • Cisco IE-5000-16S12P Industrial Ethernet Switch
  • Cisco ME 4924-10GE Switch
  • Cisco RF Gateway 10
  • Cisco SM-X Layer 2/3 EtherSwitch Service Module

O relatório oficial da Cisco (CVE-2017-3881) sobre essa falha está disponível no link abaixo:

Por ora, até que uma correção de segurança seja lançada, a recomendação da Cisco é que qualquer acesso remoto via Telnet seja desativado. É fato que por várias outras razões já passou da hora de desativar o Telnet e substituí-lo pelo SSH para acesso remoto aos seus dispositivos da infraestrutura, principalmente por causa confidencialidade e autenticidade viabilizadas pela criptografia nativa do SSH. Em outro artigo do blog intitulado "Acesso Seguro ao Roteador via SSH" o leitor pode encontrar mais informações sobre como fazer essa configuração nos seus switches e roteadores.

Fiquem atentos!

Samuel. 

5 comentários:

  1. Telnet pode ser antigo mais é amplamente usado, nesse caso desta falha outras soluções que são usadas para implementar segurança a autenticação como acl, tacacs tornam-se insolidas?

    ResponderExcluir
    Respostas
    1. O uso desses recursos torna a situação menos pior, principalmente com ACLs limitando os hosts com permissão de acesso. A verdade é que com Telnet não tem para onde correr, afinal o protocolo é totalmente inseguro por natureza. De que adianta limitar quais hosts podem acessar a caixa via Telnet se a senha pode ser facilmente capturada?

      A solução definitiva é uma só e bem simples por sinal: habilitar o SSH em todas as caixas. Há anos que a maioria das empresas que visito não têm mais Telnet habilitado nas caixas, somente SSH.

      Excluir
    2. Concordo em gênero, número e grau! O ssh deveria ser padrão e o telnet nem deveria mais ser suportado. O administrador que não usa o ssh deve ser o mesmo que não usa (ou aprende usar) o IPv6. É no mínimo uma brincadeira de roleta russa com uma pistola usar telnet nos dias de hoje.

      Excluir
  2. Ssh deveria ser padrão e o telnet nem deveria mais ser suportado.. +1

    ResponderExcluir
  3. Boa tarde, Professor Samuel!
    Boa tarde, pessoal!

    Eu sou novo membro aqui...
    Adquiri o livro recentemente, lab 06, não consigo pingar o host de outra vlan, efetuou o dot1q nas subinterfaces do roteador, mesmo assim nada, so não estou utilizando vtp (prefiri fazer manualmente pra treinar mais...) mas não acredito que seja o vtp. Onde eu posso postar o meu arquivo .pkt

    ResponderExcluir