CAPEC Details
Name Fuzzing for garnering other adjacent user/sensitive data
Likelyhood of attack Typical severity
High Medium
Summary An attacker who is authorized to send queries to a target sends variants of expected queries in the hope that these modified queries might return information (directly or indirectly through error logs) beyond what the expected set of queries should provide. Many client applications use specific query templates when interacting with a server and often automatically fill in specific fields or attributes. If the server does not verify that the query matches one of the expected templates, an attacker who is allowed to send normal queries could modify their query to try to return additional information. Fuzzing techniques involve sending random or malformed messages to a target and monitoring the target's response. In this particular attack, the fuzzing is applied to the format of the expected templates, creating variants that request additional information, exclude limiting clauses, or alter fields that identify the requester in order to subvert access controls. The attacker may not know the names of fields to request or how other modifications will affect the server response, but by attempting multiple plausible variants, they might eventually trigger a server response that divulges sensitive information. Other possible outcomes include server crashes and resource consumption if the unexpected queries cause the server to enter an unstable state or perform excessive computation.
Prerequisites The server must assume that the queries it receives follow specific templates and/or have fields or attributes that follow specific procedures. The server must process queries that it receives without adequately checking or sanitizing queries to ensure they follow these templates.
Related Weaknesses
CWE ID Description
CWE-20 Improper Input Validation
Related CAPECS
CAPEC ID Description
CAPEC-54 An adversary, aware of an application's location (and possibly authorized to use the application), probes an application's structure and evaluates its robustness by submitting requests and examining responses. Often, this is accomplished by sending variants of expected queries in the hope that these modified queries might return information beyond what the expected set of queries would provide.