Checkov crashes when evaluating a Terraform dynamic block in NSGRulePortAccessRestricted.py

[davenicoll]

Describe the bug
When checking azure_security_group_rule, azurerm_network_security_rule or azurerm_network_security_group Terraform resource types, NSGRulePortAccessRestricted.py throws a "TypeError: string indices must be integers" error whenever there's a dynamic block.

To Reproduce
Steps to reproduce the behavior:

1. Create a resource in terraform, containing a dynamic security rule -

resource "azurerm_network_security_group" "snet_nsgs" {
  count               = "${length(local.subnets)}"
  name                = "${local.root}-snet-${lookup(local.subnets[count.index], "name")}-nsg"
  location            = "${azurerm_resource_group.net_rg.location}"
  resource_group_name = "${azurerm_resource_group.net_rg.name}"
  tags                = "${local.tags}"


  dynamic "security_rule" {
    for_each = [for s in local.subnets[count.index].nsg_rules : {
      name                       = s.name
      priority                   = s.priority
      direction                  = s.direction
      access                     = s.access
      protocol                   = s.protocol
      source_port_range          = s.source_port_range
      destination_port_range     = s.destination_port_range
      source_address_prefix      = s.source_address_prefix
      destination_address_prefix = s.destination_address_prefix
      description                = s.description
    }]
    content {
      name                       = security_rule.value.name
      priority                   = security_rule.value.priority
      direction                  = security_rule.value.direction
      access                     = security_rule.value.access
      protocol                   = security_rule.value.protocol
      source_port_range          = security_rule.value.source_port_range
      destination_port_range     = security_rule.value.destination_port_range
      source_address_prefix      = security_rule.value.source_address_prefix
      destination_address_prefix = security_rule.value.destination_address_prefix
      description                = security_rule.value.description
    }
  }
}

2. Run checkov
3. Error!

Expected behavior
As checkov cannot evaluate the dynamic block, I expect the check to be skipped without throwing an error.

Desktop (please complete the following information):

• OS: Ubuntu
• Checkov Version 1.0.479