In the unlikely case that you actually have a static sbin and not just a symlink you could hack together a one-liner using file or objdump to check headers and set correct perms... but considering that everything in the dir should be either an executable or a directory, chmod a+x would work just as well.
If /usr/bin isn't a symlink to /bin or vice-versa, then you should have tools there to do the same thing.
If you somehow still have a working C compiler (or access to another language that can do syscalls or has C bindings), it's pretty easy to write a wrapper for the syscall.
If there's an rsync daemon, nfs share, etc. running, you can copy over a static busybox and fix the system that way.
If you're allowed to take the system down, it's really easy - just boot up a live image and change the permissions.
If /usr/bin isn't a symlink to /bin or vice-versa, then you should have tools there to do the same thing.
If you somehow still have a working C compiler (or access to another language that can do syscalls or has C bindings), it's pretty easy to write a wrapper for the syscall.
If there's an rsync daemon, nfs share, etc. running, you can copy over a static busybox and fix the system that way.
If you're allowed to take the system down, it's really easy - just boot up a live image and change the permissions.