Improper Neutralization of Alternate XSS Syntax

Demonstrations

The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

In the following example, an XSS neutralization routine checks for the lower-case "script" string but does not account for alternate strings ("SCRIPT", for example).

public String preventXSS(String input, String mask) {
  return input.replaceAll("script", mask);
}

See Also