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:

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170317-cmp

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.