CAPEC Definitions / CAPEC-221
CAPEC-221: Data Serialization External Entities Blowup
This attack takes advantage of the entity replacement property of certain data serialization languages (e.g., XML, YAML, etc.) where the value of the replacement is a URI. A well-crafted file could have the entity refer to a URI that consumes a large amount of resources to create a denial of service condition. This can cause the system to either freeze, crash, or execute arbitrary code depending on the URI.
Extended Description
No Extended Description.
Mitigations
This attack may be mitigated by tweaking the XML parser to not resolve external entities. If external entities are needed, then implement a custom XmlResolver that has a request timeout, data retrieval limit, and restrict resources it can retrieve locally.
This attack may be mitigated by tweaking the serialized data parser to not resolve external entities. If external entities are needed, then implement a custom resolver that has a request timeout, data retrieval limit, and restrict resources it can retrieve locally.
Relationships with other CAPECs
Prerequisites
A server that has an implementation that accepts entities containing URI values.
Related Weaknesses
CWE-611: Improper Restriction of XML External Entity Reference
