Control: SSL/TLS servers should avoid using CBC cipher suites

Description

Cipher block chaining (CBC) is a mode of operation for a block cipher in which a sequence of bits are encrypted as a single unit, or block, with a cipher key applied to the entire block. The problem with CBC mode is that the decryption of blocks is dependent on the previous ciphertext block, which means attackers can manipulate the decryption of a block by tampering with the previous block using the commutative property of XOR. If the server uses TLS 1.2 or TLS 1.1, or TLS 1.0 with CBC cipher modes, there is a chance that the server gets vulnerable to Zombie POODLE, GOLDENDOODLE, 0-Length OpenSSL and Sleeping POODLE.

Usage

Run the control in your terminal:

powerpipe control run net_insights.control.ssl_avoid_using_cbc_cipher_suite

Snapshot and share results via Turbot Pipes:

powerpipe login
powerpipe control run net_insights.control.ssl_avoid_using_cbc_cipher_suite --share

Steampipe Tables

net_tls_connection

Params

Args	Name	Default	Description	Variable
$1	domain_names	`["github.com","microsoft.com"]`	DNS domain names.	domain_names

SQL

with domain_list as (
  select
    domain,
    concat(domain, ':443') as address
  from
    jsonb_array_elements_text(to_jsonb($1 :: text [ ])) as domain
),
check_cbc_cipher as (
  select
    address,
    count(*)
  from
    net_tls_connection
  where
    address in (
      select
        address
      from
        domain_list
    )
    and version in ('TLS v1.2', 'TLS v1.1', 'TLS v1.0')
    and cipher_suite_name in (
      'TLS_RSA_WITH_AES_128_CBC_SHA',
      'TLS_RSA_WITH_AES_256_CBC_SHA',
      'TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA',
      'TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA',
      'TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA',
      'TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA',
      'TLS_RSA_WITH_3DES_EDE_CBC_SHA',
      'TLS_RSA_WITH_AES_128_CBC_SHA256',
      'TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA',
      'TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256',
      'TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256'
    )
    and handshake_completed
  group by
    address
)
select
  d.domain as resource,
  case
    when i.address is null
    or i.count < 1 then 'ok'
    else 'alarm'
  end as status,
  case
    when i.address is null
    or i.count < 1 then d.domain || ' does not use CBC cipher suites.'
    else d.domain || ' uses CBC cipher suites.'
  end as reason
from
  domain_list as d
  left join check_cbc_cipher as i on d.address = i.address;