iso27k fmea spreadsheet

5/13/2018 ISO27k FMEA Spreadsheet - slidepdf.com

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Introduction and acknowledgement

Contents

The FMEA Sample tab has the actual illustration - an analysis of possible failure modes for a firewall.

The Guidelines provide additional notes on the FMEA method, including a step-by-step process outline.

The Severity, Probability and Detectability tabs have tables demonstrating scales commonly used to rank risks by

Copyright

Disclaimer

An illustration of the application of Failure(FMEA) techniques to the analysis of

The original version of this spreadsheet was kindly provided to the ISO27k Implementers' Forum by Bala Ramasecurity risks. Subsequently, Bala kindly agreed to donate it to the ISO27k Toolkit. Apart from minor updates and

This work is copyright © 2008, ISO27k implementers' forum, some rights reserved. It is licensed under the Cwelcome to reproduce, circulate, use and create derivative works from this provided that (a) it is not sold or inImplementers’ Forum at www.ISO27001security.com, and (c) derivative works are shared under the same terms a

Risk analysis is more art than science. Don't be fooled by the numbers and formulae: the results are heavily influinformation assets and on the framing of risks being considered. For these reasons, the process is best conassessing and managing information security risks, and (b) the organization, its internal and external situation

anyone. It is impossible to guarantee that all risks have been considered and analyzed correctly. Some very exand we have some sympathy with that viewpoint.

The results of the analysis should certainly be reviewed by management (ideally including IT auditors, Legal, adjusted according to their experience, so long as the expert views are taken into consideration. Remember: jusecurity risk does not necessarily mean that it can be discounted. Organizations with immature security manageare not even recognized, due to inadequate incident detection and reporting processes.



Importa

How to

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Using p



Guideline to Carry out a Risk Assessmen

nt notes:

This method does not consider asset values. Rrisks are identified for each asset and prioritized without taking acc

The Cumulative risk for the identified asset for each threat is ascertained by the Risk Priority Number (RPN)Each asset can have more than one failure mode and for each failure mode there can be more than one cause.

For more clarification see the comments on the header in each cell of the FMEA sample worksheet

carry out the Risk Assessment (RA) using FMEA:

Identify the businesses or the services rendered by the department under the scope of RA

Compute the assets that deliver or support the business or service identified

Write down the asset number (to avoid duplication)

Write down the function of the asset in delivering or maintain the identified business or service

Now identify the failure modes for the identified function. Please note that there could be more than one failure mo

Now identify the effect, if the identified failure mode happens. That if the identified failure mode happens what will

Now refer the severity chart and choose the number relevant to the effect of the failure mode

Now identfiy the cause for the failure mode. Please note that each failure mode can have more than one cause.

Now refer to the probability chart and choose the number that is more relevant to the frequency of the cause happ

Now list down the current controls. Kindly categorize the controls as preventive and detective controls. Write each

Now refer to the detectability chart and choose a number relevant to the effectiveness of the controls.

You can now see the Risk Priority Number calculated for a failure mode of the respective asset function.

Now identify who will implement the recommended control and by what target date the recommended control wou

Refer the Probability Chart

Refer the Detectability Chart

New RPN is calculated. Compare it with the acceptable norms and if not satisfying then redo the same process.

rioritized risks

Management may decide to target, say, the top 5% of risks initially. This is an arbitrary value that can be reviewed

Following the FMEA method, the risks are assessed, RPNs calculated and then risks are ranked by RPN.

5% of 1000 (the maximum RPN value) is 50. So any RPN above 50 requires review and (probably) control improv

All risks with RPNs above 50 are identified as "HIGH RISK". This criterion is of course based on the arbitrary 5% v

If the organization is well controlled with relatively few HIGH RISK items, the 5% value may be extended to, say 15

Alternatively, if there are simply too many HIGH RISK items to tackle at once, they may be addressed in top-down

Now if the RPN is not under the acceptable value then the risk status shows "HIGH RISK", recommendation to mitdown. Kinldy list each control in separate rows.

Now if the RPN is under the acceptable value then the risk status shows "LOW RISK". Else it displays as HIGH RIrepeated from step 1.

The prioritized list of risks provides management with a rational basis for determining how much resource to applydown the list if more resources are allocated, and vice versa.



FMEA Sample

Department: XYZ Department

Sl.No. Business / Service Asset Name Asset Number Function

8 Firewall 5000 IP Spoofing 8

4 Firewall 5000 7

9 Firewall 5000 DDOS Attack 10

7 Firewall 5000 User awareness 5

5 Firewall 5000 6

Potential FailureMode(s)

Potential Technical

Effect(s)of Failure

Potential Business

Consequence(s) of Failure

S

ev

Potent

MechF

Protecting ITAssets

To blockunauthorized

requests

Rules notappropriatelyconfigured

Diversion of sensitive datatraffic, fraud

Procefo

Protecting ITAssets


requests


Entry for ExternalHackers

Disclosure or modification of

business records;prosecution; bad

PR; customer defection

Procefo

Protecting ITAssets


requests


Inability to

processelectronic

transactions; badPR; customer

defection

Procefo

Protecting ITAssets

To identifytrusted zonesby encryption

CIACompromised

Disclosure of customer database;

commercial andprivacy issues

Procefo

Protecting ITAssets


Authenticationmechanism

using legacysystems having

improper configuration

User may not

have access tothe requested

service

Staff unable towork; backlogs;

bad PRPolicie

impl



FMEA Sample

3 Firewall 5000 7

6 Firewall 5000 DDOS Attack 10

2 Firewall 5000 7

1 Firewall 5000 Data Theft 7

Protecting ITAssets

To blockunauthorizedrequests


Entry for ExternalHackers

Disclosure or modification of

business records;prosecution; bad


Prof

Protecting ITAssets


requests

Rules notappropriately

configured

Inability toprocess

electronictransactions; bad


Prof

Protecting ITAssets


Encryption level(56 bit or 128 bit)

mismatch

Data will beexposed as plain

text

Disclosure of

customer database;

commercial andprivacy issues

Policimp

Protecting ITAssets


requests

Rules notappropriately

configured

Commercial andprivacy

consequences

Proa



FMEA Sample



FMEA Sample

ontrols

Action Results

Implemented Controls

N e w

S e v

N e w

O c c

N e w

D e t

Detective Controls Detective Controls

4 64 5 3 2

4 56 5 3 2

2 40 2 5 2

1 30 Not Required Not Required 5 2 2

5 30 User Awareness User Awareness 1 5 3

Det

R

PN

RecommendedControls

Responsibility &Target CompletionDate

DetectiveControls

PreventiveControls

PreventiveControls

Increase auditfrequency

XYZ by end Jan2006


LogMonitoring


XYZ by end Jan2006



XYZ by end Jan2006


Business owner to formallyaccept risk

XYZ by endMarch 2006



FMEA Sample

ontrols

Action Results


c

R

RecommendedControls

2 28 1 4 2

1 20 1 4 2




XYZ by end Jan2006


LogMonitoring


XYZ by end Jan2006






FMEA Sample

ontrols

Action Results


R

RecommendedControls



FMEA Sample

N e

w

R P N

30

30

20

20

15



FMEA Sample

N

8

8

8

4



FMEA Sample

N



Severity

Effect SEVERITY of Effect Ranking

Catastrophic Resource not available / Problem unknown 10

Extreme 9

Very High 8

High Resource Available / Major violation of policies 7

Moderate Resource Available / Major violations of process 6

Low Resource Available / Major violations of procedures 5

Very Low Resource Available / Minor violations of policies 4

Minor Resource Available / Minor violations of process

3Very Minor Resource Available / Minor violations of procedures 2

None No effect 1

Resource not available / Problem known and cannot be

controlledResource not available / Problem known and can becontrolled



Severity



Probability

PROBABILITY of Failure Failure Prob Ranking

Very High: Failure is almost inevitable>1 in 2 10

1 in 3 9

High: Repeated failures

1 in 8 8

1 in 20 7

Moderate: Occasional failures

1 in 80 6

1 in 400 5

1 in 2,000 4

Low: Relatively few failures1 in 15,000 3

1 in 150,000 2

Remote: Failure is unlikely <1 in 1,500,000 1



Detectability

Detection Likelihood of DETECTION Ranking

10

Very Remote 9

Remote 8

Very Low 7

Low 6

Moderate 5

Moderately High 4

High 3

Very High 2

Almost Certain 1

AbsoluteUncertainty

Control cannot prevent / detect potential cause/mechanismand subsequent failure mode

Very remote chance the control will prevent / detect potentialcause/mechanism and subsequent failure mode

Remote chance the control will prevent / detect potentialcause/mechanism and subsequent failure mode

Very low chance the control will prevent / detect potentialcause/mechanism and subsequent failure mode

Low chance the control will prevent / detect potentialcause/mechanism and subsequent failure mode

Moderate chance the control will prevent / detect potentialcause/mechanism and subsequent failure mode

Moderately High chance the control will prevent / detectpotential cause/mechanism and subsequent failure mode

High chance the control will prevent / detect potentialcause/mechanism and subsequent failure mode

Very high chance the control will prevent / detect potentialcause/mechanism and subsequent failure mode

Control will prevent / detect potential cause/mechanism andsubsequent failure mode

iso27k fmea spreadsheet

Documents

identified failure mode

high risk

risk status

low risk

identified asset

risk priority number

risk assessment ra

asset number