CWE-472 - External Control of Assumed-Immutable Web Parameter
- Abstraction:Base
- Structure:Simple
- Status:Draft
- Release Date:2006-07-19
- Latest Modification Date:2025-12-11
Weakness Name
External Control of Assumed-Immutable Web Parameter
Description
The web application does not sufficiently verify inputs that are assumed to be immutable but are actually externally controllable, such as hidden form fields.
If a web product does not properly protect assumed-immutable values from modification in hidden form fields, parameters, cookies, or URLs, this can lead to modification of critical data. Web applications often mistakenly make the assumption that data passed to the client in hidden fields or cookies is not susceptible to tampering. Improper validation of data that are user-controllable can lead to the application processing incorrect, and often malicious, input. For example, custom cookies commonly store session data or persistent data across sessions. This kind of session data is normally involved in security related decisions on the server side, such as user authentication and access control. Thus, the cookies might contain sensitive data such as user credentials and privileges. This is a dangerous practice, as it can often lead to improper reliance on the value of the client-provided cookie by the server side application.
Common Consequences
Scope: Integrity
Impact: Modify Application Data
Notes: Without appropriate protection mechanisms, the client can easily tamper with cookies and similar web data. Reliance on the cookies without detailed validation can lead to problems such as SQL injection. If you use cookie values for security related decisions on the server side, manipulating the cookies might lead to violations of security policies such as authentication bypassing, user impersonation and privilege escalation. In addition, storing sensitive data in the cookie without appropriate protection can also lead to disclosure of sensitive user data, especially data stored in persistent cookies.