Server-Side Parameter Pollution (SSPP) Overview

Server-Side Parameter Pollution (SSPP) occurs when an application improperly handles or embeds user input in server-side requests to internal APIs, often without adequate encoding or validation. This vulnerability can lead to various security issues, including parameter manipulation, unauthorized data access, and application behavior modification.

How SSPP Works

  1. Parameter Injection: An attacker manipulates user input to include additional parameters or modify existing ones.
  2. Unfiltered Input: The application sends this unfiltered or inadequately sanitized input to an internal API or server-side component.
  3. Server-Side Processing: The internal API or server-side component processes the manipulated input, potentially leading to unauthorized behavior or access.

Potential Impacts

Testing for SSPP

When assessing an application for SSPP vulnerabilities, consider the following input types and locations:

  1. Query Parameters: Test URL query strings for injection opportunities. Example: http://example.com/api/resource?id=123&extra_param=malicious_value
  2. Form Fields: Manipulate form inputs to include additional or malicious parameters. Example: <input name="username" value="attacker&extra_param=malicious_value">
  3. Headers: Modify HTTP headers to include extra parameters. Example: X-Custom-Header: value&extra_param=malicious_value
  4. URL Path Parameters: Inject parameters into URL paths. Example: http://example.com/api/resource/123/extra_param=malicious_value

Enhanced Testing Techniques