Credentials sent as cleartext

Average severity: Critical

Description

The whole API or an API operation accepts user credentials sent in cleartext over an unencrypted channel. Attackers can easily intercept API calls and retrieve the credentials. They can then use the credentials to make other API calls.

For more details, see the OpenAPI Specification (OAS) v2 or v3.

Example

The following is an example of how this type of risk could look in your API definition:

OAS v2:

...  
  "schemes": [
    "http"
  ],
  ...
  "securityDefinitions": {
    "regularSecurity": {
      "type": "basic"
    }
  },
  ...
  "security": [
    {
      "regularSecurity": []
    }
  ],
  ...
}

The security section defines that the API is protected with basic authentication (username and password). The schemes section sets HTTP as the supported transportation protocol. This means that the API accepts an API call over an unencrypted HTTP connection, and expects it to have the username and password in the clear.

OAS v3:

...
  {
  "security": [
    {
      "regularSecurity": []
    }
   ]
  }
  ...
  {
  "servers": [
    {
      "url": "http://my.api.server.com/",
      "description": "API server"
    }
  ]
}
...  
  {
   "components": {
      "securitySchemes": {
         "regularSecurity": {
            "type": "http",
            "scheme": "basic"
         }
      }
   }
}

As in the previous example, the security section defines that the API is protected with basic authentication. The reusable security scheme regularSecurity from #components/securitySchemes/ section defines that type of the transport protocol is HTTP, which is matched by the URL of the server for the API.

Possible exploit scenario

Attackers can intercept the credentials simply by listening to the network traffic in a public WiFi network. They could also use a traffic logging tool on a smartphone, computer, or browser, or sniff the traffic in the network to get the credentials.

Remediation

At the very least, set  the trasnport protocol to HTTPS only so that all traffic is encrypted. You could also improve the security of the authentication method. The OAuth 2.0 accessCode flow is considered the most secure way to provide API authorization.

OAS v2:

...
  "schemes": [
    "https"
  ],
  ...
  "securityDefinitions": {
    "OAuth2": {
      "type": "oauth2",
      "flow": "accessCode",
      "scopes": {
        "readOnly": "read objects in your account"
      },
      "authorizationUrl": "https://example.com/oauth/authorize",
      "tokenUrl": "https://example.com/oauth/token", 
    }
  },
  ...
  "security" : [
    "OAuth2": [ "readOnly" ]
  ]
}

OAS v3:

...
{
	"security": [
		{
		"OAuth2": ["readOnly"]
		}
	]
}
...
{
	"servers": [
		{
			"url": "https://my.api.server.com/",
			"description": "API server"
		}
	]
}
...  
{
	"components": {
		"securitySchemes": {
			"OAuth2": {
				"type": "oauth2",
				"flows": {
					"authorizationCode": {
						"scopes": {
							"readOnly": "read objects in your account"
						},
						"authorizationUrl": "https://example.com/oauth/authorize",
						"tokenUrl": "https://example.com/oauth/token", 
					}
				}
			}
		}
	}
}

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