...
| Code Block | ||
|---|---|---|
| ||
private final void makeAccessible() { // private final
String fieldName = "i""i"; // hardcode
C c = new C();
// ...
}
class C {
private int i = 10; // private
}
|
...
| Code Block | ||
|---|---|---|
| ||
package Safe;
public class Trusted {
Trusted() { } // package private constructor
public static <T><T> T create(Class<T>Class<T> c) throws InstantiationException, IllegalAccessException {
return c.newInstance();
}
}
package Attacker;
import Safe.Trusted;
public class Attack {
public static void main(String[] args) throws InstantiationException, IllegalAccessException {
System.out.println(Trusted.create(Trusted.class)); // succeeds
}
}
|
...
| Code Block | ||
|---|---|---|
| ||
package Safe;
import java.beans.Beans;
public class Trusted {
Trusted() { }
public static <T><T> T create(Class<T>Class<T> c) {
try {
ClassLoader cl = new SafeClassLoader();
Object b = Beans.instantiate(cl, c.getName());
return c.cast(b);
} catch(Throwable t) { t.printStackTrace(); /* forward to handler */ }
return null;
}
}
// code outside the package
package Attacker;
import Safe.Trusted;
public class Attack {
public static void main(String[] args) {
Object o = Trusted.create(Trusted.class); // throws java.lang.IllegalAccessException, o = null
}
}
|
...
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
References
| Wiki Markup |
|---|
\[[Chan 99|AA. Java References#Chan 99]\] java.lang.reflect AccessibleObject \[[SCG 07|AA. Java References#SCG 07]\] Guideline 6-4 Be aware of standard APIs that perform Java language access checks against the immediate caller |
...
SEC02-J. Do not expose standard APIs that may bypass Security Manager checks to untrusted code 02. Platform Security (SEC) SEC04-J. Do not rely on the default automatic signature verification provided by URLClassLoader and java.util.jar