Pass the ISC ISC 2 Credentials SSCP Questions and answers with CertsForce

A differential backup is a partial backup that copies a selected file to tape only if the archive bit for that file is turned on, indicating that it has changed since the last full backup. A differential backup leaves the archive bits unchanged on the files it copies.

Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 3: Telecommunications and Network Security (page 69).

Also see: http://e-articles.info/e/a/title/Backup-Types/

Backup software can use or ignore the archive bit in determining which files to back up, and can either turn the archive bit off or leave it unchanged when the backup is complete. How the archive bit is used and manipulated determines what type of backup is done, as follows

Full backup

A full backup, which Microsoft calls a normal backup, backs up every selected file, regardless of the status of the archive bit. When the backup completes, the backup software turns off the archive bit for every file that was backed up. Note that "full" is a misnomer because a full backup backs up only the files you have selected, which may be as little as one directory or even a single file, so in that sense Microsoft's terminology is actually more accurate. Given the choice, full backup is the method to use because all files are on one tape, which makes it much easier to retrieve files from tape when necessary. Relative to partial backups, full backups also increase redundancy because all files are on all tapes. That means that if one tape fails, you may still be able to retrieve a given file from another tape.

Differential backup

A differential backup is a partial backup that copies a selected file to tape only if the archive bit for that file is turned on, indicating that it has changed since the last full backup. A differential backup leaves the archive bits unchanged on the files it copies. Accordingly, any differential backup set contains all files that have changed since the last full backup. A differential backup set run soon after a full backup will contain relatively few files. One run soon before the next full backup is due will contain many files, including those contained on all previous differential backup sets since the last full backup. When you use differential backup, a complete backup set comprises only two tapes or tape sets: the tape that contains the last full backup and the tape that contains the most recent differential backup.

Incremental backup

An incremental backup is another form of partial backup. Like differential backups, Incremental Backups copy a selected file to tape only if the archive bit for that file is turned on. Unlike the differential backup, however, the incremental backup clears the archive bits for the files it backs up. An incremental backup set therefore contains only files that have changed since the last full backup or the last incremental backup. If you run an incremental backup daily, files changed on Monday are on the Monday tape, files changed on Tuesday are on the Tuesday tape, and so forth. When you use an incremental backup scheme, a complete backup set comprises the tape that contains the last full backup and all of the tapes that contain every incremental backup done since the last normal backup. The only advantages of incremental backups are that they minimize backup time and keep multiple versions of files that change frequently. The disadvantages are that backed-up files are scattered across multiple tapes, making it difficult to locate any particular file you need to restore, and that there is no redundancy. That is, each file is stored only on one tape.

Full copy backup

A full copy backup (which Microsoft calls a copy backup) is identical to a full backup except for the last step. The full backup finishes by turning off the archive bit on all files that have been backed up. The full copy backup instead leaves the archive bits unchanged. The full copy backup is useful only if you are using a combination of full backups and incremental or differential partial backups. The full copy backup allows you to make a duplicate "full" backup—e.g., for storage offsite, without altering the state of the hard drive you are backing up, which would destroy the integrity of the partial backup rotation.

Some Microsoft backup software provides a bizarre backup method Microsoft calls a daily copy backup. This method ignores the archive bit entirely and instead depends on the date- and timestamp of files to determine which files should be backed up. The problem is, it's quite possible for software to change a file without changing the date- and timestamp, or to change the date- and timestamp without changing the contents of the file. For this reason, we regard the daily copy backup as entirely unreliable and recommend you avoid using it.

The Differential Backup Method is additive because the time and tape space required for each night's backup grows during the week as it copies the day's changed files and the previous days' changed files up to the last full backup.

Archive Bits

Unless you've done a lot of backups in your time you've probably never heard of an Archive Bit. An archive bit is, essentially, a tag that is attached to every file. In actuality, it is a binary digit that is set on or off in the file, but that's crummy technical jargon that doesn't really tell us anything. For the sake of our discussion, just think of it as the flag on a mail box. If the flag is up, it means the file has been changed. If it's down, then the file is unchanged.

Archive bits let the backup software know what needs to be backed up. The differential and incremental backup types rely on the archive bit to direct them.

Backup Types

Full or Normal

The "Full" or "normal" backup type is the most standard. This is the backup type that you would use if you wanted to backup every file in a given folder or drive. It backs up everything you direct it to regardless of what the archive bit says. It also resets all archive bits (puts the flags down). Most backup software, including the built-in Windows backup software, lets you select down to the individual file that you want backed up. You can also choose to backup things like the "system state".

Incremental

When you schedule an incremental backup, you are in essence instructing the software to only backup files that have been changed, or files that have their flag up. After the incremental backup of that file has occured, that flag will go back down. If you perform a normal backup on Monday, then an incremental backup on Wednesday, the only files that will be backed up are those that have changed since Monday. If on Thursday someone deletes a file by accident, in order to get it back you will have to restore the full backup from Monday, followed by the Incremental backup from Wednesday.

Differential

Differential backups are similar to incremental backups in that they only backup files with their archive bit, or flag, up. However, when a differential backup occurs it does not reset those archive bits which means, if the following day, another differential backup occurs, it will back up that file again regardless of whether that file has been changed or not.

Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 69.

And: HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-Hill/Osborne, 2002, chapter 9: Disaster Recovery and Business continuity (pages 617-619).

And: http://www.brighthub.com/computing/windows-platform/articles/24531.aspx

The Business Impact Analysis is critical for the development of a business continuity plan (BCP). It identifies risks, critical processes and resources needed in case of recovery and quantifies the impact a disaster will have upon the organization. The development of a mission statement is normally performed before the BIA.

A BIA (business impact analysis ) is considered a functional analysis, in which a team collects data through interviews and documentary sources; documents business functions, activities, and transactions ; develops a hierarchy of business functions; and finally applies a classification scheme to indicate each individual function’s criticality level.

BIA Steps

The more detailed and granular steps of a BIA are outlined here:

1. Select individuals to interview for data gathering.

2. Create data-gathering techniques (surveys, questionnaires, qualitative and quantitative approaches).

3. Identify the company’s critical business functions.

4. Identify the resources these functions depend upon.

5. Calculate how long these functions can survive without these resources.

6. Identify vulnerabilities and threats to these functions.

7. Calculate the risk for each different business function.

8. Document findings and report them to management.

Reference(s) used for this question:

Hernandez CISSP, Steven (2012-12-21). Official (ISC)2 Guide to the CISSP CBK, Third Edition ((ISC)2 Press) (Kindle Location 21076). Auerbach Publications. Kindle Edition.

and

Harris, Shon (2012-10-18). CISSP All-in-One Exam Guide, 6th Edition (p. 905-910). McGraw-Hill. Kindle Edition.

The exposure factor is a measure of the magnitude of loss or impact on the value of an asset.

The probability is the chance or likelihood, in a finite sample, that an event will occur or that a specific loss value may be attained should the event occur.

A vulnerability is the absence or weakness of a risk-reducing safeguard.

A threat is event, the occurrence of which could have an undesired impact.

Source: ROTHKE, Ben, CISSP CBK Review presentation on domain 3, August 1999.

Selecting and Alternate Site would not be done within the initial BIA. It would be done at a later stage of the BCP and DRP recovery effort. All of the other choices were steps that would be conducted during the BIA. See below the list of steps that would be done during the BIA.

A BIA (business impact analysis ) is considered a functional analysis, in which a team collects data through interviews and documentary sources; documents business functions, activities, and transactions ; develops a hierarchy of business functions; and finally applies a classification scheme to indicate each individual function’s criticality level.

BIA Steps

1. Select individuals to interview for data gathering.

2. Create data-gathering techniques (surveys, questionnaires, qualitative and quantitative approaches).

3. Identify the company’s critical business functions.

4. Identify the resources these functions depend upon.

5. Calculate how long these functions can survive without these resources.

6. Identify vulnerabilities and threats to these functions.

7. Calculate the risk for each different business function.

8. Document findings and report them to management.

Reference(s) used for this question:

Harris, Shon (2012-10-18). CISSP All-in-One Exam Guide, 6th Edition (p. 905-909). McGraw-Hill. Kindle Edition.

Remember this is a NOT question. Hot sites do not provide a false sense of security since they are the best disaster recovery alternate for backup site that you rent.

A Cold, Warm, and Hot site is always a rental place in the context of the CBK. This is definivily the best choices out of the rental options that exists. It is fully configured and can be activated in a very short period of time.

Cold and Warm sites, not hot sites, provide a false sense of security because you can never fully test your plan.

In reality, using a cold site will most likely make effective recovery impossible or could lead to business closure if it takes more than two weeks for recovery.

Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 8: Business Continuity Planning and Disaster Recovery Planning (page 284).

Companies can set predefined thresholds for the number of certain types of errors that will be allowed before the activity is considered suspicious. The threshold is a baseline for violation activities that may be normal for a user to commit before alarms are raised. This baseline is referred to as a clipping level.

The following are incorrect answers:

Clipping levels enable a security administrator to customize the audit trail to record only those violations which are deemed to be security relevant. This is not the best answer, you would not record ONLY security relevant violations, all violations would be recorded as well as all actions performed by authorized users which may not trigger a violation. This could allow you to indentify abnormal activities or fraud after the fact.

Clipping levels enable the security administrator to customize the audit trail to record only actions for users with access to user accounts with a privileged status. It could record all security violations whether the user is a normal user or a privileged user.

Clipping levels enable a security administrator to view all reductions in security levels which have been made to user accounts which have incurred violations. The keyword "ALL" makes this question wrong. It may detect SOME but not all of violations. For example, application level attacks may not be detected.

Reference(s) used for this question:

Harris, Shon (2012-10-18). CISSP All-in-One Exam Guide, 6th Edition (p. 1239). McGraw-Hill. Kindle Edition.

and

TIPTON, Hal, (ISC)2, Introduction to the CISSP Exam presentation.

An Intrusion Detection System (IDS) is a system that is used to monitor network traffic or to monitor host audit logs in order to determine if any violations of an organization's system security policy have taken place.

Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 48.

It is the systems auditor that should lead the effort to ensure that the security controls are in place and effective. The audit would verify that the controls comply with polices, procedures, laws, and regulations where applicable. The findings would provide these to senior management.

The following answers are incorrect:

the local security specialist. Is incorrect because an independent review should take place by a third party. The security specialist might offer mitigation strategies but it is the auditor that would ensure the effectiveness of the controls

the business manager. Is incorrect because the business manager would be responsible that the controls are in place, but it is the auditor that would ensure the effectiveness of the controls.

the central security manager. Is incorrect because the central security manager would be responsible for implementing the controls, but it is the auditor that is responsibe for ensuring their effectiveness.

Some disadvantages of a statistical anomaly-based ID are that it will not detect an attack that does not significantly change the system operating characteristics, or it may falsely detect a non-attack event that had caused a momentary anomaly in the system.

Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 49.

Audit trails maintain a record of system activity by system or application processes and by user activity. In conjunction with appropriate tools and procedures, audit trails can provide individual accountability, a means to reconstruct events, detect intrusions, and identify problems. Audit trail controls are considered technical controls. Monitoring and tracking of incidents is more an operational control related to incident response capability.

Reference(s) used for this question:

SWANSON, Marianne, NIST Special Publication 800-26, Security Self-Assessment Guide for Information Technology Systems, November 2001 (Pages A-50 to A-51).

NOTE: NIST SP 800-26 has been superceded By: FIPS 200, SP 800-53, SP 800-53A

You can find the new replacement at: http://csrc.nist.gov/publications/PubsSPs.html

However, if you really wish to see the old standard, it is listed as an archived document at:

http://csrc.nist.gov/publications/PubsSPArch.html

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.

As stated in SP 800-34 Rev. 1:

To be effective, the plan must be maintained in a ready state that accurately reflects system requirements, procedures, organizational structure, and policies. During the Operation/Maintenance phase of the SDLC, information systems undergo frequent changes because of shifting business needs, technology upgrades, or new internal or external policies.

As a general rule, the plan should be reviewed for accuracy and completeness at an organization-defined frequency (at least once a year for the purpose of the exam) or whenever significant changes occur to any element of the plan. Certain elements, such as contact lists, will require more frequent reviews.

Remember, there could be two good answers as specified above. Either once a year or whenever significant changes occur to the plan. You will of course get only one of the two presented within you exam.

Reference(s) used for this question:

NIST SP 800-34 Revision 1

If audit trails have been properly defined and implemented, they will record information that can assist in detecting intrusions.

Source: HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-Hill/Osborne, 2002, Chapter 4: Access Control (page 186).

A HIDS does not consume large amounts of system resources is the correct choice. HIDS can consume inordinate amounts of CPU and system resources in order to function effectively, especially during an event.

All the other answers are characteristics of HIDSes

A HIDS can:

scrutinize event logs, critical system files, and other auditable system resources;

look for unauthorized change or suspicious patterns of behavior or activity

can send alerts when unusual events are discovered

Traffic anomaly-based is the correct choice. An anomaly based IDS can detect unknown attacks. A traffic anomaly based IDS identifies any unacceptable deviation from expected behavior based on network traffic.

Protocol anomaly based is not the best choice as while a protocol anomaly based IDS can identify unknown attacks, this type of system is more suited to identifying deviations from established protocol standards such as HTTP. This type of IDS faces problems in analyzing complex or custom protocols.

Pattern matching is not the best choice as a pattern matching IDS cannot identify unknown attacks. This type of system can only compare packets against signatures of known attacks.

Stateful matching is not the best choice as a statful matching IDS cannot identify unknown attacks. This type of system works by scanning traffic streams for patterns or signatures of attacks.

Layer 5 of the OSI model is the Session Layer. This layer provides a logical persistent connection between peer hosts. A session is analogous to a conversation that is necessary for applications to exchange information.

The session layer is responsible for establishing, managing, and closing end-to-end connections, called sessions, between applications located at different network endpoints. Dialogue control management provided by the session layer includes full-duplex, half-duplex, and simplex communications. Session layer management also helps to ensure that multiple streams of data stay synchronized with each other, as in the case of multimedia applications like video conferencing, and assists with the prevention of application related data errors.

The session layer is responsible for creating, maintaining, and tearing down the session.

Three modes are offered:

(Full) Duplex: Both hosts can exchange information simultaneously, independent of each other.

Half Duplex: Hosts can exchange information, but only one host at a time.

Simplex: Only one host can send information to its peer. Information travels in one direction only.

Another aspect of performance that is worthy of some attention is the mode of operation of the network or connection. Obviously, whenever we connect together device A and device B, there must be some way for A to send to B and B to send to A. Many people don’t realize, however, that networking technologies can differ in terms of how these two directions of communication are handled. Depending on how the network is set up, and the characteristics of the technologies used, performance may be improved through the selection of performance-enhancing modes.

Basic Communication Modes of Operation

Let's begin with a look at the three basic modes of operation that can exist for any network connection, communications channel, or interface.

Simplex Operation

In simplex operation, a network cable or communications channel can only send information in one direction; it's a “one-way street”. This may seem counter-intuitive: what's the point of communications that only travel in one direction? In fact, there are at least two different places where simplex operation is encountered in modern networking.

The first is when two distinct channels are used for communication: one transmits from A to B and the other from B to A. This is surprisingly common, even though not always obvious. For example, most if not all fiber optic communication is simplex, using one strand to send data in each direction. But this may not be obvious if the pair of fiber strands are combined into one cable.

Simplex operation is also used in special types of technologies, especially ones that are asymmetric. For example, one type of satellite Internet access sends data over the satellite only for downloads, while a regular dial-up modem is used for upload to the service provider. In this case, both the satellite link and the dial-up connection are operating in a simplex mode.

Half-Duplex Operation

Technologies that employ half-duplex operation are capable of sending information in both directions between two nodes, but only one direction or the other can be utilized at a time. This is a fairly common mode of operation when there is only a single network medium (cable, radio frequency and so forth) between devices.

While this term is often used to describe the behavior of a pair of devices, it can more generally refer to any number of connected devices that take turns transmitting. For example, in conventional Ethernet networks, any device can transmit, but only one may do so at a time. For this reason, regular (unswitched) Ethernet networks are often said to be “half-duplex”, even though it may seem strange to describe a LAN that way.

Full-Duplex Operation

In full-duplex operation, a connection between two devices is capable of sending data in both directions simultaneously. Full-duplex channels can be constructed either as a pair of simplex links (as described above) or using one channel designed to permit bidirectional simultaneous transmissions. A full-duplex link can only connect two devices, so many such links are required if multiple devices are to be connected together.

Note that the term “full-duplex” is somewhat redundant; “duplex” would suffice, but everyone still says “full-duplex” (likely, to differentiate this mode from half-duplex).

For a listing of protocols associated with Layer 5 of the OSI model, see below:

ADSP - AppleTalk Data Stream Protocol

ASP - AppleTalk Session Protocol

H.245 - Call Control Protocol for Multimedia Communication

ISO-SP

OSI session-layer protocol (X.225, ISO 8327)

iSNS - Internet Storage Name Service

The following are incorrect answers:

Synchronous and Asynchronous are not session layer modes.

Half simplex does not exist. By definition, simplex means that information travels one way only, so half-simplex is a oxymoron.

Reference(s) used for this question:

Hernandez CISSP, Steven (2012-12-21). Official (ISC)2 Guide to the CISSP CBK, Third Edition ((ISC)2 Press) (Kindle Locations 5603-5636). Auerbach Publications. Kindle Edition.

and

http://www.tcpipguide.com/free/t_SimplexFullDuplexandHalfDuplexOperation.htm

and

http://www.wisegeek.com/what-is-a-session-layer.htm

A network-based IDS usually provides reliable, real-time information without consuming network or host resources.

Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 48.

Displaying the directory contents of a folder can alter the last access time on each listed file.

Using a write blocker is wrong because using a write blocker ensure that you cannot modify the data on the host and it prevent the host from writing to its hard drives.

Made a full-disk image is wrong because making a full-disk image can preserve all data on a hard disk, including deleted files and file fragments.

Created a message digest for log files is wrong because creating a message digest for log files. A message digest is a cryptographic checksum that can demonstrate that the integrity of a file has not been compromised (e.g. changes to the content of a log file)

Domain: LEGAL, REGULATIONS, COMPLIANCE AND INVESTIGATIONS

References:

AIO 3rd Edition, page 783-784

NIST 800-61 Computer Security Incident Handling guide page 3-18 to 3-20

Controls provide accountability for individuals accessing information. Assurance procedures ensure that access control mechanisms correctly implement the security policy for the entire life cycle of an information system.

Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 2: Access control systems (page 33).