HTML allows fields in a web form to be visible or hidden. Hidden fields supply values to a web server but do not provide the user with a mechanism to modify their contents. However, there are techniques that attackers can use to modify these contents anyway. A web servlet that uses a GET form to obtain parameters can also accept these parameters through a URL. URLs allow a user to specify any parameter names and values in the web request. Consequently, hidden form fields should not be considered any more trustworthy than visible form fields.
Noncompliant Code Example
The following servlet noncompliant code example demonstrates a servlet that accepts a visible field and a hidden field, and echoes them back to the user. The visible parameter is sanitized before being passed to the browser, but the hidden field is not.
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Trusting the contents of hidden form fields may lead to all sorts of nasty problems.
Rule | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
IDS14-J | High | Probable | High | P6 | L2 |
Automated Detection
Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| The Checker Framework |
| Tainting Checker | Trust and security errors (see Chapter 8) | ||||||
| CodeSonar |
| JAVA.IO.INJ.CODE | Code Injection (Java) | ||||||
| Fortify | 6.10.0120 | Hidden_Field | Implemented |
Bibliography
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