Updating mac os x tiger to leopard
which randomizes the locations of some libraries in memory.Vulnerabilities that corrupt program memory often rely on known addresses for these library routines, which allow injected code to launch processes or change files.Signatures can also be used to ensure that one program replacing another is truly an "update", and carry any special security privileges across to the new version.
Several researchers noted that the Library Randomization feature added to Leopard was ineffective compared to mature implementations on other platforms, and that the new "secure Guest account" could be abused by Guests to retain access to the system even after the Leopard log out process erased their home directory.
Leopard introduces a significantly revised desktop, with a redesigned Dock, Stacks, a semitransparent menu bar, and an updated Finder that incorporates the Cover Flow visual navigation interface first seen in i Tunes.
Other notable features include support for writing 64-bit graphical user interface applications, an automated backup utility called Time Machine, support for Spotlight searches across multiple machines, and the inclusion of Front Row and Photo Booth, which were previously included with only some Mac models.
Leopard can run on older hardware as long as they have a G4 upgrade installed running at the 867 MHz or faster, have at least 9 GB free of hard drive space, 512 MB RAM and have a DVD drive.
Leopard however will not run on the 900 MHz i Book G3 models even though they exceed the minimum 867 MHz requirement.