OS Security Components 1. Log-On Procedure A formal log-on procedure is the OS’s first line of defense against unauthorized access. When user initiates the process, a dialog box requesting the user’s ID and password will appear. System will compare ID and password. a. If Match – log-on attempt is authenticated. b. Incorrect – log-on attempt fails and a message is returned to the user. OS will not reveal whether failure is caused by ID or password. OS will allow user to reenter log-on info. After a specified no. of attempts (usually no more than five), system should lock out the user from the system. 2. Access Token If log-on attempt is successful, OS creates an access token which contains key info about the user, including user ID, password, user group, and privileges granted to the user. Info in the access token is used to approve all actions the user attempts during the session. 3. Access Control List An access control list is assigned to each IT resource (computer directory, data file, program, or printer), which controls access to the resources. The list contains info that defines the access privileges for all valid users of the resources. If a user attempts to access a resource, OS compares ID and privileges in the access token with the access control list. If there is match, user is granted access.
4. Discretionary Access Privileges In distributed systems, end users may control own resources. Resource owners may be granted discretionary access privileges which allow them to grant access privileges (i.e. read-only privilege or read and write permissions) to other users. However, Discretionary access control needs to be closely supervised to prevent security breaches resulting from too liberal use. Threats to OS Integrity OS Control Objectives may not be achieved due to flaws that are exploited either accidentally or intentionally. 1. Accidental Threats - hardware failures, errors in user app. May cause whole segments of memory to be dumped to disks and printers, resulting in unintentional disclosure of confidential info. 2. Intentional Threats – attempts to illegally access data or violate user privacy for financial gain. Sources are: a. Privileged personnel who abuse their authority. b. Individuals, both internal and external to the org who browse the OS to identify and exploit security flaws. c. Individuals who intentionally (or accidentally) insert computer viruses or other forms of destructive programs into the OS. OS Controls and Audit Tests Issue with OS Security Controls is with SOX compliance. To preserve OS integrity, the following areas are examined: 1. Access Privileges Privileges should be carefully administered and closely monitored for compliance with org policy and principles of internal control.
- Spring '13
- Cryptography, IT Audit , Public-key cryptography, Pretty Good Privacy