Chapter 12: Mobile, Linux, & macOS

Source Code

the sequence of instructions that is written in human readable language, before it is turned into machine language (zeroes and ones).

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No access

Software Tokens

- Apps that generate a temporary password. - Considered a cheaper alternative to hardware tokens, as issuing a hardware token to a large number of users has a high cost.

Disks

A disk utility on the OS Ubuntu Linux. Users can perform the most common disk-related tasks including partition management, mount or unmount, format disks and query Analysis and Reporting Technology, (S.M.A.R.T.).

Adaptive Brightness

A feature on Android devices that allows the device to decide the optimal screen brightness based on the amount of ambient light.

Cron Table

A file which contains the schedule of cron entries to be run and at specified times. To schedule a task, the user adds a row. The new row specifies the minute, hour, day of the month, and the day of the week the task should be executed. When the specified date and time arrives, the task is executed.

rogue antivirus

A form of malicious software and internet fraud that misleads users into believing there is a virus on their computer. It aims to convince them to pay for a fake malware removal tool that actually installs malware on their computer.

sandbox

A location of the OS that keeps code isolated from other resources and other code.

Walled Garden Model

All apps must be submitted to and approved by Apple before they are released to users.

BranchCache

Allows files to be read even when a connection cannot be made with the file server. Does not support writing to files unless connectivity to the file server can be established.

Port Security

Also known as MAC Filtering, this is used to restrict which devices can physically connect to the network.

chmod

A Linux command that allows users to change the permissions of files that they own.

passwd

A Linux command that allows users to change their own password at the terminal.

kill

A Linux command that allows users to end the processes that they have started.

ps

A Linux command that allows users to monitor their own processes. Without specifying options, this command only shows users their programs that are running in the current terminal.

iwconfig

A Linux command that allows users to set and view their wireless settings.

chown

A Linux command that allows users to switch both the owner and the group of a file or files.

sudo (super user do)

A Linux command that grants a user root access without actually changing their profile. The access is granted for a limited time, but only if the user is listed in the /etc/sudoers file.

ps -e

A Linux command that lists information about every process running

dd (disk dupilcate)

A Linux command used to copy files and partitions, and create temporary swap files. Should be used with extreme caution.

cat

A Linux command used to display (or concatenate) the entire contents of a text file to the screen.

shutdown

A Linux command used to halt and reboot the operating system.

ext4

A Linux file system which support up to 1 Exbibyte (EiB) of data. Supports an unlimited number of subdirectories. An improved version of the ext3 filesystem with an extended feature set and better performance.

Time Machine

A backup tool included with macOS. Users choose an external drive to be used as a backup destination device and connect it to the Mac via USB, FireWire or Thunderbolt. This program will prepare the disk to receive backups and, when the disk is ready, it performs incremental backups periodically.

SDK (software development kit)

A collection of software development tools in one installable package that facilitate the creation of applications.

apt-get

A command that used to install and manage software on Debian based Linux distributions.

Disk Utility

A macOS program created to help diagnose and solve disk-related problems. In addition to supporting the main disk maintenance tasks, it also supports Verify Disk Permissions and Repair Disk Permissions (a common troubleshooting step in macOS). This can also be used to backup disks to image files and perform an image recovery to disk from image files. These files contain the entire contents of a disk.

GPS (Global Positioning System)

A navigation system that determines the time and geographical location of the device by using messages from satellites in space and a receiver on Earth.

Terminal

A program included on Mac OS, much like the command line interface on Windows, which can be used to run Unix commands within the Mac OS or to access other machines.

Shell

A program that interprets the commands from the keyboard and passes them to the operating system. Acts as an interface layer between the user and kernel.

Unix

A proprietary operating system written in the C programming language. macOS and iOS are based upon the Berkley Standard Distribution (BSD) version of Unix.

Keychain

A security credentials and password management system for macOS. This helps you to manage SSH and GPG keys in a convenient and secure manner.

Keyring

A security credentials manager for Ubuntu Linux used to store secrets on your behalf. The secrets are stuff like SSH keys, keys to Wi-Fi networks, and etcetera.

Accelerometer

A sensor inside the device that detects how it is being held and will change the screen orientation appropriately.

PXE (Preboot Execution Environment)

A special boot type that downloads an image from a server on the network.

Query S.M.A.R.T. attributes

A task that can be performed using disk utility software in macOS. Can detect and report attributes about a disk's health. The goal of this is to anticipate disk failure, allowing the user to move the data to a healthy disk before the failing disk becomes inaccessible.

Mount or Unmount disk partitions

A task that can be performed using disk utility software in macOS. On Unix-like systems, mounting a partition relates to the process of binding a partition of a disk or a disk image file (usually a .iso) to a folder location.

Bad Sector Check

A task that can be performed using disk utility software in macOS. When a disk sector is flagged as bad, it becomes harmless to the OS because it will no longer be used to store data. Many bad sectors could be an indicator of a failing disk. Disk utilities can salvage data stored in bad sectors by moving it to healthy disk sectors.

Xcode

An Apple tool that allows developers to write and test new apps. (Can only be used on macOS).

Reliability Monitor

An application available in some Windows operating systems that will show a timeline of events recorded by Windows. This includes security warnings, application failures and other informational messages. You can view when the application crashed, error/crash details and try to identify a pattern or cause for the crashes.

VPN (Virtual Private Network)

An encrypted connection over the Internet from a device to a network. The encrypted connection helps ensure that sensitive data is safely transmitted. It prevents unauthorized people from eavesdropping on the traffic and allows the user to conduct work remotely. Instead of using a dedicated leased line, it uses "virtual" connections routed through the internet from the company's private network to the remote site or employee.

Local Snapshot

An instantaneous "picture" of your server's file system at a certain period of time. This picture captures the entire file system as it was when the snapshot is taken. When your backup disk isn't available, Time Machine automatically uses this to help you restore files.

vi

An interactive text editor that is display-oriented. The screen of your terminal acts as a window into the file you are editing.

Swift

An macOS interactive programming language used to write software for phones, desktops, servers, or anything else that runs code.

HFS Plus (Extended Hierarchical File System)

Apple Mac workstations use this file system. Supports many of the same features as NTFS in Windows, but not native file/folder encryption. In macOS High Sierra, and later this file system, updated to the Apple File System (APFS), which does support native file encryption. Has a maximum volume and file size of 8 ExaBytes.

File permissions

Are built into the file system structure and provide a mechanism to define permissions to every file and directory.

IPS (Indoor Positioning Systems)

Can determine device location by triangulating its proximity to other radio signals such as Wi-Fi access-points.

cd

Changes the current directory.

PRL (Preferred Roaming List)

Configuration information that a cellular phone needs to communicate on networks other than its own so that a call can be made outside of the carrier's network

PRI (Primary Rate ISDN)

Configures the data rates between the device and the cell tower. This ensures that the device is able to communicate with the tower at the correct rate.

SMS Payment System

Consumers send a SMS message to a carrier's special phone number containing a payment request. The seller is informed the payment has been received and is cleared to release the goods. The charge is added to the customer's phone bill. CONS: Slow speed, poor reliability, and poor security.

Signature

Contains sample of code used by viruses and malware.

cp

Copies files from source to a destination.

mkdir

Creates a directory under the current directory.

Is

Displays the files inside a directory.

pwd

Displays the name of the current directory.

--x

Execution only.

iOS Erase Data

If the passcode fails 10 times, the screen goes black, and all data on the device is deleted. To restore the iOS device and data, if you have backups, use either the Restore and Backup option in iTunes or the Manage Storage option in iCloud.

Cron Service

In Linux and macOS, this is responsible for scheduled tasks. As a service, it runs in the background and executes tasks at specific dates and times. This program uses a schedule table called a "cron table" that can be edited with the crontab command.

d

Indicates it is a directory.

-

Indicates it is a file.

Wi-Fi calling

Instead of using the cellular carrier's network, modern smartphones can use the internet to transport voice calls by taking advantage of a local Wi-Fi hotspot

Kernel

Is responsible for allocating CPU time and memory to processes. It also manages the file system and communications in response to system calls.

ifconfig

Linux command for finding out a computer's IP address information.

mv

Moves files or directories.

Patches

OS updates released periodically by OS vendor to address new known vulnerabilities.

rw-------

Octal form: 600 User: Can read and write permissions. Others: No permissions at all. The settings is used when the owner wants to keep the data file private.

rw--r--r

Octal form: 644 Owners: read and write a file. Others: only read the file. A common setting for data files that all the users may read, but only the owner may change.

rw-rw-rw-

Octal form: 666 Everyone can read and write to the file. Bad idea.

rwx------

Octal form: 700 Owner: Read, write, and execute the file. Nobody else has any rights. This setting is useful for programs that only the owner may use and must be kept private from others.

rwxr-xr-x

Octal form: 755 Owner: Read, write, and execute the file. Others: Only read and execute the file. This setting is common for programs that are used by all users on the system.

rwxrwxrwx

Octal form: 777 There is no restrictions on permissions. Anybody may do anything: read, write, or execute the file. Not a desirable setting.

Linux Terminal Emulators

Popular programs such as eterm, xterm, konsole, gnome-terminal.

DRM (Digital Rights Management) Server

Provides you the ability to control how people can consume your content.

r-x

Read and execution.

rw-

Read and write.

r--

Read only.

rwx

Read, write, and execution.

rm

Removed the files and directories.

grep

Searches a file for a particular pattern of characters, and displays all lines that contain that pattern.

Hardware Tokens

Smartcards, USB sticks or one-time-use password generators. Are more secure, but are less practical and more costly.

MDM (mobile device management)

Software is used to manage groups of mobile devices like smartphones and tablets. Because these devices run different operating systems than their PC counterparts, are often used by employees at home or on public wireless networks and can download applications from app stores, special management software is needed to ensure their security.

Firmware

Software that is permanently stored in a chip (such as the BIOS on a motherboard). Usually held in non-volatile memory, such as ROM or Flash, this is a type of software designed to provide low-level functionality for a device.

Inherence Factor

Something only the user is like biometric characteristics such as fingerprints

Possession Factor

Something the user has such as ATM cards, Hardware Tokens, Software Tokens, or a mobile phone.

Knowledge Factor

Something the user knows like a password or PIN

ext3

The 64-bit Linux file system that was the first to support journaling, which is a technique that tracks and stores changes to the hard drive and helps prevent file system corruption.

bash

The Bourne again shell (Bash) is a common application to offer a shell command line; other common shell applications are the C shell, the Bourne shell, and the Kern shell.

sideloading

This gives users the ability to directly install apps without going through the Android storefront interface.

A computer at work has become infected with malware. After several attempts to remove the malware using a professional anti-malware tool you find the malicious software is not fully removed. What should you do next?

The next logical step here is to restore the computer to a known-good backup. You can try to determine what backups are available compared to when the malware was first discovered. If no backups are available or no backups before the infection are available reformatting the PC is an acceptable last resort.

NFC (Near Field Communication)

This method is used mostly in physical store transactions. A consumer pays for good or services by waving the phone near the payment system. Based on a unique ID, the payment is charged directly against a pre-paid account or bank account. Is also used in mass-transportation services, the public parking sector, and many other consumer areas.

rooting

Used only on Android devices to gain privileged or root level access for modifying code or installing software that is not intended for the device. Voids the manufacturer's warranty.

jailbreaking

Used only on iOS devices to remove manufacturer restrictions allowing them to run arbitrary user-code, grant users full access to the file system and full access to kernel modules. Voids the manufacturer's warranty.

tar

Used to create an Archive and extract the Archive files. - Used to create compressed or uncompressed Archive files and also maintain and modify them.

Direct Mobile Billing

Using a mobile billing option during check-out, a user identifies him or herself (usually through a two-factor authentication) and allows the charge to be added to the mobile service bill. PROS: security, convenience, and no need for bank cards or credit cards.

Remote Backup

When a device copies its data to cloud storage using a backup app. If data needs to be restored, run the backup app and access the website to retrieve the data.

-wx

Write and execution.

-w-

Write only.

swap partition

used by the operating system to supplement system RAM. If applications or data files use up all the available space in RAM, data is written to the [Insert Term Here] on a disk and is treated as if it were stored in RAM.