It is Illegal
QUOTE(Spanish license agreement)
3. Responsabilidades de los Usuarios Finales.
A. Sujetos a la Concesión de Licencia anteriormente mencionada, no puede, completa o parcialmente, copiar, fotocopiar, reproducir, traducir, derivar el código de origen, modificar, desmontar, descompilar, crear trabajos derivados basados en el Programa o eliminar los avisos o etiquetas del propietario del Programa sin previo consentimiento, realizado por escrito por Blizzard.
My Translation, might not be the same to your agreement but close enough for you to get the idea.
QUOTE
3. User Responsabilities
A. Attached to the previous license agreement, you may not, partially or completely, copy, photocopy, reproduce, translate, overwrite the source code, MODIFY it, disemble it, decompile it, create works based on the program or eliminate the announcements or stickies from the creator of the program without permission, Program made by Blizzard