CAPEC-57 - Utilizing REST's Trust in the System Resource to Register Man in the Middle

This attack utilizes a REST(REpresentational State Transfer)-style applications' trust in the system resources and environment to place man in the middle once SSL is terminated. Rest applications premise is that they leverage existing infrastructure to deliver web services functionality. An example of this is a Rest application that uses HTTP Get methods and receives a HTTP response with an XML document. These Rest style web services are deployed on existing infrastructure such as Apache and IIS web servers with no SOAP stack required. Unfortunately from a security standpoint, there frequently is no interoperable identity security mechanism deployed, so Rest developers often fall back to SSL to deliver security. In large data centers, SSL is typically terminated at the edge of the network - at the firewall, load balancer, or router. Once the SSL is terminated the HTTP request is in the clear (unless developers have hashed or encrypted the values, but this is rare). The attacker can utilize a sniffer such as Wireshark to snapshot the credentials, such as username and password that are passed in the clear once SSL is terminated.

Once the attacker gathers these credentials, they can submit requests to the web service provider just as authorized user do. There is not typically an authentication on the client side, beyond what is passed in the request itself so once this is compromised, then this is generally sufficient to compromise the service's authentication scheme.

Severity

Likelihood

Confidentiality

Integrity

Availability

  • Attack Methods 2
  • Protocol Manipulation
  • Injection
  • Purposes 2
  • Penetration
  • Exploitation
  • Scopes 1
  • Gain privileges / assume identity
  • Authorization
  • Access_Control
  • Confidentiality

Low level: To insert a network sniffer or other listener into the communication stream

Opportunity to intercept must exist beyond the point where SSL is terminated.

The attacker must be able to insert a listener actively (proxying the communication) or passively (sniffing the communication) in the client-server communication path.

Attacker may use a network sniffer to identify authentication credentials once SSL is terminated.

Implementation: Implement message level security such as HMAC in the HTTP communication

Design: Utilize defense in depth, do not rely on a single security mechanism like SSL

Design: Enforce principle of least privilege