Section: Cryptography
Explanation/Reference:
When evidence from a crime is to be used in the prosecution of a criminal it is critical that you follow the law when handling that evidence. Part of that process is called chain of custody and is when you maintain proactive and documented control over ALL evidence involved in a crime.
Failure to do this can lead to the dismissal of charges against a criminal because if the evidence is compromised because you failed to maintain of chain of custody.
A chain of custody is chronological documentation for evidence in a particular case, and is especially important with electronic evidence due to the possibility of fraudulent data alteration, deletion, or creation. A fully detailed chain of custody report is necessary to prove the physical custody of a piece of evidence and show all parties that had access to said evidence at any given time.
Evidence must be protected from the time it is collected until the time it is presented in court.
The following answers are incorrect:
- Locking the laptop in your desk: Even this wouldn't assure that the defense team would try to challenge chain of custody handling. It's usually easy to break into a desk drawer and evidence should be stored in approved safes or other storage facility.
- Making a disk image for examination: This is a key part of system forensics where we make a disk image of the evidence system and study that as opposed to studying the real disk drive. That could lead to loss of evidence. However if the original evidence is not secured than the chain of custoday has not been maintained properly.
- Cracking the admin password with chntpw: This isn't correct. Your first mistake was to compromise the chain of custody of the laptop. The chntpw program is a Linux utility to (re)set the password of any user that has a valid (local) account on a Windows system, by modifying the crypted password in the registry's SAM file. You do not need to know the old password to set a new one. It works offline which means you must have physical access (i.e., you have to shutdown your computer and boot off a linux floppy disk). The bootdisk includes stuff to access NTFS partitions and scripts to glue the whole thing together. This utility works with SYSKEY and includes the option to turn it off. A bootdisk image is provided on their website at http://freecode.com/projects/ chntpw .
The following reference(s) was used to create this question:
For more details and to cover 100% of the exam Qs, subscribe to our holistic Security+ 2014 CBT Tutorial at:
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and
http://en.wikipedia.org/wiki/Chain_of_custody
and
http://www.datarecovery.com/forensic_chain_of_custody.asp

Explanation/Reference:
The Bell-LaPadula model focuses on data confidentiality and access to classified information, in contrast to the Biba Integrity Model which describes rules for the protection of data integrity.
In this formal model, the entities in an information system are divided into subjects and objects.
The notion of a "secure state" is defined, and it is proven that each state transition preserves security by moving from secure state to secure state, thereby proving that the system satisfies the security objectives of the model.
The Bell-LaPadula model is built on the concept of a state machine with a set of allowable states in a system. The transition from one state to another state is defined by transition functions.
A system state is defined to be "secure" if the only permitted access modes of subjects to objects are in accordance with a security policy.
To determine whether a specific access mode is allowed, the clearance of a subject is compared to the classification of the object (more precisely, to the combination of classification and set of compartments, making up the security level) to determine if the subject is authorized for the specific access mode.
The clearance/classification scheme is expressed in terms of a lattice. The model defines two mandatory access control (MAC) rules and one discretionary access control (DAC) rule with three security properties:
The Simple Security Property - a subject at a given security level may not read an object at a higher security level (no read-up).
The property (read "star"-property) - a subject at a given security level must not write to any object at a lower security level (no write-down). The property is also known as the Confinement property.
The Discretionary Security Property - use an access control matrix to specify the discretionary access control.
The transfer of information from a high-sensitivity document to a lower-sensitivity document may happen in the Bell-LaPadula model via the concept of trusted subjects. Trusted Subjects are not restricted by the property. Untrusted subjects are.
Trusted Subjects must be shown to be trustworthy with regard to the security policy. This security model is directed toward access control and is characterized by the phrase: "no read up, no write down." Compare the Biba model, the Clark-Wilson model and the Chinese Wall.
With Bell-LaPadula, users can create content only at or above their own security level (i.e. secret researchers can create secret or top-secret files but may not create public files; no write-down).
Conversely, users can view content only at or below their own security level (i.e. secret researchers can view public or secret files, but may not view top-secret files; no read-up).
Strong Property
The Strong Property is an alternative to the Property in which subjects may write to objects with only a matching security level. Thus, the write-up operation permitted in the usual Property is not present, only a write-to-same level operation. The Strong Property is usually discussed in the context of multilevel database management systems and is motivated by integrity concerns.
Tranquility principle
The tranquility principle of the Bell-LaPadula model states that the classification of a subject or object does not change while it is being referenced. There are two forms to the tranquility principle: the "principle of strong tranquility" states that security levels do not change during the normal operation of the system and the "principle of weak tranquility" states that security levels do not change in a way that violates the rules of a given security policy.
Another interpretation of the tranquility principles is that they both apply only to the period of time during which an operation involving an object or subject is occurring. That is, the strong tranquility principle means that an object's security level/label will not change during an operation (such as read or write); the weak tranquility principle means that an object's security level/label may change in a way that does not violate the security policy during an operation.
Reference(s) used for this question:
http://en.wikipedia.org/wiki/Biba_Model
http://en.wikipedia.org/wiki/Mandatory_access_control
http://en.wikipedia.org/wiki/Discretionary_access_control
http://en.wikipedia.org/wiki/Clark-Wilson_model
http://en.wikipedia.org/wiki/Brewer_and_Nash_model

Section: Analysis and Monitoring
Explanation/Reference:
A host-based IDS can review the system and event logs in order to detect an attack on the host and to determine if the attack was successful.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 48.

Explanation/Reference:
This the best of the four answers as a defense that depends on multiple layers is superior to one where all protection is embedded in a single layer (e.g., a firewall). Defense in depth would include all categories of controls.
The Following answers are incorrect:
"Concept of a pass through device that only allows certain traffic in and out" is incorrect. This is one definition of a firewall which can be a component of a defense in depth strategy in combination with other measures.
"Concept of preventative controls" is incorrect. This is a component of a defense in depth strategy but the core concept is that there must be multiple layers of defenses.
"Concept of defensive controls" is incorrect. This is a component of a defense in depth strategy but the core concept is that there must be multiple layers of defenses.
References:
http://en.wikipedia.org/wiki/Defense_in_depth_(computing)
http://www.nsa.gov/snac/support/defenseindepth.pdf