| Name |
SOAP Array Blowup |
|
| Likelyhood of attack |
Typical severity |
| Medium |
High |
|
| Summary |
An adversary may execute an attack on a web service that uses SOAP messages in communication. By sending a very large SOAP array declaration to the web service, the attacker forces the web service to allocate space for the array elements before they are parsed by the XML parser. The attacker message is typically small in size containing a large array declaration of say 1,000,000 elements and a couple of array elements. This attack targets exhaustion of the memory resources of the web service. |
| Prerequisites |
This type of an attack requires the attacker to know the endpoint of the web service, and be able to reach the endpoint with a malicious SOAP message. |
| Solutions | Enforce strict schema validation. The schema should enforce a maximum number of array elements. If the number of maximum array elements can't be limited another validation method should be used. One such method could be comparing the declared number of items in the array with the existing number of elements of the array. If these numbers don't match drop the SOAP packet at the web service layer. |
| Related Weaknesses |
|
CWE ID
|
Description
|
| CWE-770 |
Allocation of Resources Without Limits or Throttling |
|
| Related CAPECS |
|
CAPEC ID
|
Description
|
| CAPEC-130 |
An adversary causes the target to allocate excessive resources to servicing the attackers' request, thereby reducing the resources available for legitimate services and degrading or denying services. Usually, this attack focuses on memory allocation, but any finite resource on the target could be the attacked, including bandwidth, processing cycles, or other resources. This attack does not attempt to force this allocation through a large number of requests (that would be Resource Depletion through Flooding) but instead uses one or a small number of requests that are carefully formatted to force the target to allocate excessive resources to service this request(s). Often this attack takes advantage of a bug in the target to cause the target to allocate resources vastly beyond what would be needed for a normal request. |
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