Installing Unapproved Software

A subject installs software that is not considered appropriate by the organization.

A subject intentionally introduces and attempts to execute malware on a system.

A subject unintentionally introduces and attempts to execute malware on a system. This is can be achieved through various methods, such as phishing, malvertising, torrented downloads, and social engineering.

A subject installs software that is not inherently malicious, but is not wanted, commonly known as “greyware” or “potentially unwanted programs”.

By only allowing pre-approved software to be installed and run on corporate devices, the subject is unable to install software themselves.

An Acceptable Use Policy (AUP) is a set of rules outlining acceptable and unacceptable uses of an organization's computer systems and network resources. It acts as a deterrent to prevent employees from conducting illegitimate activities by clearly defining expectations, reinforcing legal and ethical standards, establishing accountability, specifying consequences for violations, and promoting education and awareness about security risks.

A web proxy can allow for specific web resources to be blocked, preventing clients from successfully connecting to them.

The Principle of Least Privilege should be enforced, and period reviews of permissions conducted to ensure that accounts have the minimum level of access required to complete duties as per their role.

Google's Chrome browser stores the history of accessed websites and files downloaded.

On Windows, this information is stored in the following location:

C:/Users/<Username>/AppData/Local/Google/Chrome/User Data/Default/

On macOS:

/Users/<Username>/Library/Application Support/Google/Chrome/Default/

On Linux:

/home/<Username>/.config/google-chrome/Default/

Where /Default/ is referenced in the paths above, this is the default profile for Chrome, and can be replaced if a custom profile is used. In this location one database file is relevant, history.sqlite.
 

This database file can be opened in software such as DB Browser For SQLite. The ‘downloads’ and ‘urls’ tables are of immediate interest to understand recent activity within Chrome.

Microsoft's Edge browser stores the history of accessed websites and files downloaded.

On Windows, this information is stored in the following location:

C:\Users\<Username>\AppData\Local\Microsoft\Edge\User Data\Default\

On macOS:

/Users/<Username>/Library/Application Support/Microsoft Edge/Default/

On Linux:

/home/<Username>/.config/microsoft-edge/Default/

Where /Default/ is referenced in the paths above, this is the default profile for Edge, and can be replaced if a custom profile is used. In this location one database file is relevant, history.sqlite.
 

This database file can be opened in software such as DB Browser For SQLite. The ‘downloads’ and ‘urls’ tables are of immediate interest to understand recent activity within Chrome.

Mozilla's Firefox browser stores the history of accessed websites.

On Windows, this information is stored in the following location:

C:\Users\<Username>\AppData\Roaming\Mozilla\Firefox\Profiles\<Profile Name>\

On macOS:

/Users/<Username>/Library/Application Support/Firefox/Profiles/<Profile Name>/

On Linux:

/home/<Username>/.mozilla/firefox/<Profile Name>/

In this location two database files are relevant, places.sqlite (browser history and bookmarks) and favicons.sqlite (favicons for visited websites and bookmarks).
 

These database files can be opened in software such as DB Browser For SQLite.

The Debian Package Management (dpkg) utility is responsible for software installation and management. This tool provides one or more log files, located at /var/log/dpkg.log.

This log contains the timestamp, the action conducted, and the package name and version.

To view pakage installs, the following command can be used: grep “ install ” /var/log/dpkg.log*

To view package uninstalls, the following command can be used: grep “ remove ” /var/log/dpkg.log*

This detection is not enabled by default and requires additional configuration.

System Monitor (Sysmon) Event ID 1 is used to record process execution. Reviewing these logs can determine what software has been run on a system.

LNK files or Shortcut files are stored in the location C:\Users\<user>\AppData\Roaming\Microsoft\Windows\Recent Items and have the “.lnk” file extension.

These files are automatically created when a user account accesses a file through Windows Explorer.

This artifact can provide information as to when a file was accessed, modified, and created, the file path and name, and the file size. .LNK files persist even if the actual file has been deleted, helping to uncover if a file has been accessed then subsequently deleted or moved as it is no longer present in the recorded full file path.

In modern versions of the Windows operating system, the prefetch feature serves an important function in speeding up the run time of applications. It does this by creating a cache of information on an application on its first run that is is stored for later reference in c:\windows\prefetch, these files are created with the extension .pf and have the following format <EXECUTABLE>-<HASH>.pf.

These created files contain the created and modified timestamps of the respective file, the file size, process path, how many times it has been run, the last time it was run, and resources it references in the first 10 seconds of execution.

Since every executable that is run will have a prefetch file created when the feature is enabled, the prefetch directory and the contents within it can offer new and valuable insights during an investigation, particularly when the original executable no longer exists.