Topic: permissions set on etc folder

[sits]

SME 7.1
I had a client tell me he did chmod 644 to the etc dir, and now he can't access his files apart from some.

to regain access to etc I had him chmod 775 to etc folder now he can work again.

My Question is:
Can the default permissions be restored using the upgrade option from the SME CD, or is there a script available to reset them.

Or worse case senario Backup and a full Rebuild will be required.

[sits]

Plenty have looked at this post, surely someone has an answer one way or another.