CAPEC-57: Utilizing REST's Trust in the System Resource to Obtain Sensitive Data
Attack Pattern ID: 57
Abstraction: Detailed
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Description
This attack utilizes a REST(REpresentational State Transfer)-style applications' trust in the system resources and environment to obtain sensitive data once SSL is terminated.
Extended Description
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 adversary 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 adversary 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.
Likelihood Of Attack
Medium
Typical Severity
Very High
Relationships
This table shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf and ParentOf, and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as CanFollow, PeerOf, and CanAlsoBe are defined to show similar attack patterns that the user may want to explore.
Nature
Type
ID
Name
ChildOf
Standard Attack Pattern - A standard level attack pattern in CAPEC is focused on a specific methodology or technique used in an attack. It is often seen as a singular piece of a fully executed attack. A standard attack pattern is meant to provide sufficient details to understand the specific technique and how it attempts to accomplish a desired goal. A standard level attack pattern is a specific type of a more abstract meta level attack pattern.
Find a REST-style application that uses SSL: The adversary must first find a REST-style application that uses SSL to target. Because this attack is easier to carry out from inside of a server network, it is likely that an adversary could have inside knowledge of how services operate.
Experiment
Insert a listener to sniff client-server communication: The adversary inserts a listener that must exist beyond the point where SSL is terminated. This can be placed on the client side if it is believed that sensitive information is being sent to the client as a response, although most often the listener will be placed on the server side to listen for client authentication information.
Techniques
Run wireshark or tcpdump on a device that is on the inside of a firewall, load balancer, or router of a network and capture traffic after SSL has been terminated
Exploit
Gather information passed in the clear: If developers have not hashed or encrypted data sent in the sniffed request, the adversary will be able to read this data in the clear. Most commonly, they will now have a username or password that they can use to submit requests to the web service just as an authorized user
Prerequisites
Opportunity to intercept must exist beyond the point where SSL is terminated.
The adversary must be able to insert a listener actively (proxying the communication) or passively (sniffing the communication) in the client-server communication path.
Skills Required
[Level: Low]
To insert a network sniffer or other listener into the communication stream
Consequences
This table specifies different individual consequences associated with the attack pattern. The Scope identifies the security property that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in their attack. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a pattern will be used to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Scope
Impact
Likelihood
Confidentiality
Access Control
Authorization
Gain Privileges
Mitigations
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
Example Instances
The Rest service provider uses SSL to protect the communications between the service requester (client) to the service provider. In the instance where SSL is terminated before the communications reach the web server, it is very common in enterprise data centers to terminate SSL at a router, firewall, load balancer, proxy or other device, then the adversary can insert a sniffer into the communication stream and gather all the authentication tokens (such as session credentials, username/passwords combinations, and so on). The Rest service requester and service provider do not have any way to detect this attack.
Related Weaknesses
A Related Weakness relationship associates a weakness with this attack pattern. Each association implies a weakness that must exist for a given attack to be successful. If multiple weaknesses are associated with the attack pattern, then any of the weaknesses (but not necessarily all) may be present for the attack to be successful. Each related weakness is identified by a CWE identifier.
CAPEC mappings to ATT&CK techniques leverage an inheritance model to streamline and minimize direct CAPEC/ATT&CK mappings. Inheritance of a mapping is indicated by text stating that the parent CAPEC has relevant ATT&CK mappings. Note that the ATT&CK Enterprise Framework does not use an inheritance model as part of the mapping to CAPEC.
Description
This table shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf and ParentOf, and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as CanFollow, PeerOf, and CanAlsoBe are defined to show similar attack patterns that the user may want to explore.
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