=== How to fix it in Java SE

include::../../common/fix/code-rationale.adoc[]

[cols="a"]
|===
h| Non-compliant code example
|
[source,java]
----
@Controller
public class ExampleController
{
    @GetMapping(value = "/exec")
    public void exec(@RequestParam("command") String command) throws IOException {

        Runtime.getRuntime().exec(command); // Noncompliant
    }
}
----
h| Compliant solution
|
[source,java]
----
@Controller
public class ExampleController
{
    @GetMapping(value = "/exec")
    public void exec(@RequestParam("command") String command) throws IOException {
        List<String> allowedCmds = new ArrayList<String>();
        allowedCmds.add("/usr/bin/ls");
        allowedCmds.add("/usr/bin/cat");
        if (allowedCmds.contains(command)){
          Process proc = Runtime.getRuntime().exec(command);
        }
    }
}
----
|===

++java.lang.Runtime++ is sometimes used over ++java.lang.ProcessBuilder++ due to ease of use. Flexibility in methods often introduces security issues as edge cases are easily missed. The compliant solution logic is also applied to ++java.lang.ProcessBuilder++.

=== How does this work?

include::../../common/fix/introduction.adoc[]

include::../../common/fix/pre-approved-list.adoc[]