Mac OS X Operating System MEMORY

01/05/15

Mac OS X Operating System MEMORY At start up, the MAC OSX it divides the Random Access Memory into two broad sections. The system partition is a saved portion which always begins at the lowest addressable byte of memory and then extends upward. The other portion is available for use by software components and applications. When launching an application, the system OS only allows for a specific portion of memory to be utilized in what is called an application partition.
The system Heap is the main part of the system partition which exclusively reserves itself for the operating system and software components. The Heap loads system code, resources and data structures, including the system buffering and queues. The Heap starts at the low memory end and only expands when needed to the high memory area. In multitasking situations, each application is limited in its memory partition. It is only allotted in total what is assigned as its maximum intended usage to not over access memory usage.
If the application requires the use of more memory, the RAM grants the application Temporary memory from the Heap to allow for smoother function ability. The operating environment is controlled by the system global variables which is the elapsed time of each open applications since system start up. The Stack is an area of the application partition which utilizes the LIFO, it releases space at the top of the stack to ensure that no unallocated holes occur within the stack. The a5 world in the application partition is always a fixed amount.

FILE MANAGEMENT
Every computer system created has had some sort of filing system set in place for its end user. With that being said, it must be recognized that not all of computer operating systems use the same methods of organizing documents. As time has passed, so too have some of the antiquated forms of file management. Gone are the days where one had to store everything on giant hard drives the size of refrigerators, along with the use of floppy disk to save or run items. In today’s modern era of technology, society is able to explore new area of file management with the introduction of the ‘iCloud’ based system. Along with these advancements, the super corporate named company of Apple has still uses some of its previous forms of file management in order to enhance its current products.
In the case of Apple’s Mac OS X, the file system is broken into four key domains. The first domain is the user domain. It is within this portion of the filing system that resources are kept with regards to the specific user that logs on to the device. Although this portions basically covers all of its users, this field shows only the ‘home directory’ of only the user that is currently logged on. User home directories can reside on the computer’s boot volume (in the /Users directory) or on a network volume.
The local domain encloses files/ applications only on the specific computer that can be shared with all its users. This domain is typically managed by the system, but users with administrative privileges may add, remove, or modify items in this domain. (Warrell, 2013 )
The network domain is similar to the local domain only with the difference being that it can share with all users on the local area network. Items in this domain are typically located on network file servers and are under the control of a network administrator.
The system domain holds all of the software for the system that is originally installed by Apple. These files are needed in order for the system to function. Users cannot add, delete, or modify objects in this location.

SECURITY
Mac OSX was designed from the ground up with security in mind. Mac has enjoyed a fairly high rating for years as a leader in security for the most part due to the company keeping the systems internal workings a secret. As they moved to OSX they based the OS on open source code that is available to everyone. They did keep key components secret so as to not allow anyone to have access to the security of the system. They have shared some of this as they are now allowing antivirus programs to be installed on the system now and that means they need to share the code that is in some of the deepest levels of the OS. This is only shared with reputable companies and not allowed into the “wild”. This was a big step for Apple as sharing this information has always been a huge no no for them. This sharing of information does allow antivirus companies to create security suites for the OS but it can also allow the source code to be shared with people who want to do harm to Mac users. The other main thing that has kept Mac on the cleaner side of this is they have a very small market share in the world. The current Market Share for Mac is just above 5%. In the grand scheme of things this is not enough for malware writers to pay attention to. Those who write malware do this mostly for financial gain. Looking at it from this stand point the small percentage of users is not enough to make most malware writers want to spend the time to create malware that will run on a Mac. The security of a Mac is also quite formable. For instance no process that is outside the OS runs as root. Root is the Mac equivalent to running as Administrator in a Windows machine. There are some differences and we will get into this later in this paper.

The first thing we should go over is access rights. This can be quite complicated. Mac has lead the way in ensuring access rights are not blurred. The top of the chain is Root. Root essentially has access to everything. As stated above the only things allowed to run as root, without going through an extra security screen, are deep level OS files that require that kind of access. The user can bring up a terminal window in root but it does require a password that was set by the person who setup the OS. Any process that wants that kind of access must have that password and a user must enter it. The system files are also protected and the user is required to have the password and the permissions to access those files. If a program were installed that had malicious intent it would require this information on most Macs. Of course this can be circumvented by the end user who did not set the password in the first place. This is true of any OS. If the user has set up the system to require little or nothing to gain access to these files then the user has ended their own security.

Very few antivirus companies have entered into the game with Mac. The reasons for this are simple enough. As stated above the user base is low and most of them do not believe you can get an infection on a Mac computer. This is not true. There are some very high level infections that can take control of a Mac computer. This includes viruses, rootkits, botnets, and general malware have all been found running in Mac computers. Apple has recently had to change the way they advertise their products and remove anything that stated they cannot get infected. This has changed the playing field a bit and more people are looking to the security industry to help secure their Mac computers. This has also woken the malware writers to the fact that Macs have become more vulnerable. More infections have been found in the wild for Macs in the last 2 years then all previous years Mac has produced computers.

The most seen infections for Macs have been the Ransom/Scareware variety. These are always a fake program that has been altered to look like something legitimate. In many cases they are designed to look exactly like your favorite antivirus begins a fake scan that tells you it found many horrible infections on your system. Most of the names of the malware will be names pulled out of recent headlines to ensure the end user knows something about them and is afraid to not act. The infection then pops a link in front of the user saying something like “…. Infections were found on your computer. We will remove these infections and cleanup your computer if you are willing to pay $XX.XX. This is usually not a huge amount of money as the malware writers want this to look legitimate. They make the money later as in order to get the “cleaning” they are offering they require your credit card. Once they have you credit card information they will sell it. This is the most used vector, the user. In the world of IT security, the largest issue any admin will come across is not the OS that is used in the network but the people operating it.

Mac has worked hard to secure the OS they have been working on but the main issue is making sure the user is up to date, not the OS or the antivirus. Updates are always important and will help in keeping the world safe and nothing can replace a good antivirus. We has operators of these machines need to be aware of what is happening out there and keep the information we want secure in a safe place.

Refences

* http://www.netmarketshare.com/operating-system-market-share.aspx?qprid=10&qpcustomd=0&qpcustomb=

* http://www.welivesecurity.com/2014/03/21/10-years-of-mac-os-x-malware/

* Inside Macintosh: Memory_APPLE.INC 1985 (reassessed 2007)

* Apple Inside Macintosh Volume I, II, III_CAROLINE ROSE 1985 (reassessed 2004) * Warrell, A. (August 16, 2013). File Management on the Apple Mac Computers. Retrieved from http://www-public.jcu.edu.au/libcomp/computing/computers/JCUPRD_034360 *