Arbitrary code execution in de.tum.in.ase:artemis-java-test-sandbox

Summary

Because of the missing checkLink(String) override in the SecurityManager, students can load libraries and execute arbitrary code.

Details

Using System.load(String) or System.loadLibrary​(String) students can load and execute arbitrary code.

private static native void start(List<String> args);

public static void main(String[] args) {
  System.load(new File("path_to_lib.so").getAbsolutePath());
  start(List.of(args));
}

Adding this to the security manager (and a translation) should fix the issue:

@Override
public void checkExec(String cmd) {
  try {
    if (enterPublicInterface())
      return;
    throw new SecurityException(localized("security.error_link")); //$NON-NLS-1$
  } finally {
    exitPublicInterface();
  }
}

PoC

See details.

Impact

Arbitrary code execution.