Recovery controls are intended to bring the environment back to regular operations
For your exam you should know below information about different security controls
Deterrent Controls
Deterrent Controls are intended to discourage a potential attacker. Access controls act as a
deterrent to threats and attacks by the simple fact that the existence of the control is enough to
keep some potential attackers from attempting to circumvent the control. This is often because the
effort required to circumvent the control is far greater than the potential reward if the attacker is
successful, or, conversely, the negative implications of a failed attack (or getting caught) outweigh
the benefits of success. For example, by forcing the identification and authentication of a user,
service, or application, and all that it implies, the potential for incidents associated with the system
is significantly reduced because an attacker will fear association with the incident. If there are no
controls for a given access path, the number of incidents and the potential impact become infinite.
Controls inherently reduce exposure to risk by applying oversight for a process. This oversight
acts as a deterrent, curbing an attacker's appetite in the face of probable repercussions.
The best example of a deterrent control is demonstrated by employees and their propensity to
intentionally perform unauthorized functions, leading to unwanted events.
When users begin to understand that by authenticating into a system to perform a function, their
activities are logged and monitored, and it reduces the likelihood they will attempt such an action.
Many threats are based on the anonymity of the threat agent, and any potential for identification
and association with their actions is avoided at all costs.
It is this fundamental reason why access controls are the key target of circumvention by attackers.
Deterrents also take the form of potential punishment if users do something unauthorized. For
example, if the organization policy specifies that an employee installing an unauthorized wireless
access point will be fired, that will determine most employees from installing wireless access
points.
Preventative Controls Preventive controls are intended to avoid an incident from occurring. Preventative access controls keep a user from performing some activity or function. Preventative controls differ from deterrent controls in that the control is not optional and cannot (easily) be bypassed. Deterrent controls work on the theory that it is easier to obey the control rather than to risk the consequences of bypassing the control. In other words, the power for action resides with the user (or the attacker). Preventative controls place the power of action with the system, obeying the control is not optional. The only way to bypass the control is to find a flaw in the control's implementation.
Compensating Controls Compensating controls are introduced when the existing capabilities of a system do not support the requirement of a policy. Compensating controls can be technical, procedural, or managerial. Although an existing system may not support the required controls, there may exist other technology or processes that can supplement the existing environment, closing the gap in controls, meeting policy requirements, and reducing overall risk.
For example, the access control policy may state that the authentication process must be encrypted when performed over the Internet. Adjusting an application to natively support encryption for authentication purposes may be too costly. Secure Socket Layer (SSL), an encryption protocol, can be employed and layered on top of the authentication process to support the policy statement.
Other examples include a separation of duties environment, which offers the capability to isolate certain tasks to compensate for technical limitations in the system and ensure the security of transactions. In addition, management processes, such as authorization, supervision, and administration, can be used to compensate for gaps in the access control environment.
Detective Controls Detective controls warn when something has happened, and are the earliest point in the post-incident timeline. Access controls are a deterrent to threats and can be aggressively utilized to prevent harmful incidents through the application of least privilege. However, the detective nature of access controls can provide significant visibility into the access environment and help organizations manage their access strategy and related security risk.
As mentioned previously, strongly managed access privileges provided to an authenticated user offer the ability to reduce the risk exposure of the enterprise's assets by limiting the capabilities that authenticated user has. However, there are few options to control what a user can perform once privileges are provided. For example, if a user is provided write access to a file and that file is damaged, altered, or otherwise negatively impacted (either deliberately or unintentionally), the use of applied access controls will offer visibility into the transaction. The control environment can be
established to log activity regarding the identification, authentication, authorization, and use of
privileges on a system.
This can be used to detect the occurrence of errors, the attempts to perform an unauthorized
action, or to validate when provided credentials were exercised. The logging system as a detective
device provides evidence of actions (both successful and unsuccessful) and tasks that were
executed by authorized users.
Corrective Controls
When a security incident occurs, elements within the security infrastructure may require corrective
actions. Corrective controls are actions that seek to alter the security posture of an environment to
correct any deficiencies and return the environment to a secure state. A security incident signals
the failure of one or more directive, deterrent, preventative, or compensating controls. The
detective controls may have triggered an alarm or notification, but now the corrective controls must
work to stop the incident in its tracks. Corrective controls can take many forms, all depending on
the particular situation at hand or the particular security failure that needs to be dealt with.
Recovery Controls
Any changes to the access control environment, whether in the face of a security incident or to
offer temporary compensating controls, need to be accurately reinstated and returned to normal
operations. There are several situations that may affect access controls, their applicability, status,
or management.
Events can include system outages, attacks, project changes, technical demands, administrative
gaps, and full-blown disaster situations. For example, if an application is not correctly installed or
deployed, it may adversely affect controls placed on system files or even have default
administrative accounts unknowingly implemented upon install.
Additionally, an employee may be transferred, quit, or be on temporary leave that may affect policy
requirements regarding separation of duties. An attack on systems may have resulted in the
implantation of a Trojan horse program, potentially exposing private user information, such as
credit card information and financial data. In all of these cases, an undesirable situation must be
rectified as quickly as possible and controls returned to normal operations.
The following answers are incorrect:
Deterrent - Deterrent controls are intended to discourage a potential attacker
Preventive - Preventive controls are intended to avoid an incident from occurring
Corrective - Corrective control fixes components or systems after an incident has occurred
The following reference(s) were/was used to create this question:
CISA Review Manual 2014 Page number 44 and Official ISC2 CISSP guide 3rd edition Page number 50 and 51