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Memahami Sistem Aplikasi
© 2010 – CHANDRA YULISTIA, CISA 2
Pemahaman Sistem
System Factoring
Breaking a system up into subsystems
A subsystem is logical component rather than physical component
Function Factoring
Management function
Development, implementation, operation, maintenance
Application function
Accounting cycles
– Sales & collections
– Payroll & personnel
– Acquisitions & payments
– Inventoty & warehousing
– Treasury
© 2010 – CHANDRA YULISTIA, CISA 3
Memahami Sistem
Faktorisasi Sistem (System Factoring)
Sistem
Subsistem Subsistem
Subsubsistem Subsubsistem Subsubsistem Subsubsistem Subsubsistem
Level 0
Level 1
Level 2
© 2010 – CHANDRA YULISTIA, CISA 4
Faktorisasi Fungsi (Function Factoring)
Fungsi-fungsi TI
Sistem Manajemen Siklus Akuntansi
Subsistem Manajemen Sistem Aplikasi
Subsistem Aplikasi
Memahami Sistem
© 2010 – CHANDRA YULISTIA, CISA 5
Memahami Sistem
Teknik-teknik
Wawancara, Observasi, Tinjauan Lapangan
Data Flow Diagram (DFD)
Document Flowchart
© 2010 – CHANDRA YULISTIA, CISA 6
Data Flow Diagram
Empat gambar digunakan dalam DFD yang masing masing
mencerminkan:
Entity
Entitas di luar sistem yang sedang dipelajari
Dapat mengirimkan atau menerima data ke/dari sistem
Proses
Selalu menunjukkan terjadinya perubahan data
Data flow yang masuk ke suatu Proses, berbeda dari Data flow
yang keluar dari Proses tersebut.
Data Store
Data Flow
Dimungkinkan terjadi 2 data flow yang bersamaan
Masing-masing harus diberi label yang sesuai
Data Store
Entity
Proses
Data flow
© 2010 – CHANDRA YULISTIA, CISA 7
Decision Tree
Customer
Tipe B
Tipe A
Tidak Pernah menunggak
Pernah menunggak
Tipe Credit History Diskon
Tidak Pernah menunggak
Pernah menunggak
10%
7.5%
5%
2%
Tipe lainnya 0 %
© 2010 – CHANDRA YULISTIA, CISA 8
Decision Tables
Ada 4 bagian:
1. condition stub
– berisikan kondisi yang akan dipilih
2. condition entry
– berisikan kemungkinan dari kondisi yang akan dipilih
3. action stub
– berisikan tindakan yang akan dilakukan, baik bila kondisi
terpenuhi atau tidak
4. action entry
– berisikan tindakan mana yang akan dilakukan dan yang tidak
dilakukan untuk masing masing kombinasi kondisi
Bila jumlah condition stub ada x, maka jumlah kemungkinan tindakan
ada N=2x
Decision tables sangat penting bagi auditor bila melakukan
substantive test untuk mengetahui apakah ada kemungkinan kondisi
yang belum di cakup dalam logika program aplikasi
© 2010 – CHANDRA YULISTIA, CISA 9
Decision Tables
Condition 1 2 3 4
Customer Utama ? Y Y T T
Pernah Menunggak ? Y T Y T
Action
Diskon 8% 10.00% 0.00% 5%
Order dikirim 1 hari? Y Y N N
Contoh – Decision Tables:
Konsep
Pengendalian Aplikasi
© 2010 – CHANDRA YULISTIA, CISA 11
Risiko pada Aplikasi
Risiko Risiko Risiko Risiko Risiko Risiko Risiko Risiko
Risiko Risiko Risiko Risiko Risiko Risiko Risiko
© 2010 – CHANDRA YULISTIA, CISA 12
Risiko pada Aplikasi
© 2010 – CHANDRA YULISTIA, CISA 13
Risiko pada Aplikasi
© 2010 – CHANDRA YULISTIA, CISA 14
Pengendalian TI
Operation Management
Application System Control
IS Management
System Development Management
Programming Management
Data Management
Quality Assurance Management
Security Management
Top Management
© 2010 – CHANDRA YULISTIA, CISA 15
Pengendalian TI
© 2010 – CHANDRA YULISTIA, CISA 16
Pengendalian Aplikasi TI
AC1 Source Data Preparation and Authorisation
AC2 Source Data Collection and Entry
AC3 Accuracy, Completeness and Authenticity Checks
AC4 Processing Integrity and Validity
AC5 Output Review, Reconciliation and Error Handling
AC6 Transaction Authentication and Integrity
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Application Controls Overview
Application Controls
Boundary Controls
Input Controls
Communication Controls
Processing Controls
Database Controls
Output Controls
© 2010 – CHANDRA YULISTIA, CISA 18 1
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Application Controls Overview
Boundary Controls
Comprise the components that establish the interface with the user
and the system
Input Controls
Comprise the components that capture, prepare, and enter
commands and data into systems
Communication Controls
Comprise the components that transmit data among subsystems and
systems
© 2010 – CHANDRA YULISTIA, CISA 19 1
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Application Controls Overview
Processing Controls
Comprise the components that perform decision making,
computation, classification, ordering, and summarization of data in
the system
Database Controls
Comprise the components that define, add, access, modify and
delete data in the system
Communication Controls
Comprise the components that retrieve and present data to user of
the system
Audit
Pengendalian Aplikasi
© 2010 – CHANDRA YULISTIA, CISA 21 2
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Input
Controls
© 2010 – CHANDRA YULISTIA, CISA 22 2
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Input Controls
Introduction
Components in the input subsystem are responsible for bringing both data
and instructions into the system
Input controls are critical because :
In many systems, the largest number of controls exist in the input subsystem
Input subsystem sometimes involve large amounts of routine, monotonous
human intervention and error prone
Input subsystem is often become the target of fraud
© 2010 – CHANDRA YULISTIA, CISA 23 2
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Input Controls
Data Input Methods
State
or
Event
Recording
Medium
Keyboarding
Direct
Reading
Direct
Entry
Personal Computer
Optical Character Recognition
Magnetic Ink Character Recognition
Mark Sensing
Digitizer
Image Reader
Point-of-sales Device
Automatic Teller Machine
Personal Computer
Touch Screen
Mice, Joystick, Trackball
Voice, Sound
Video
© 2010 – CHANDRA YULISTIA, CISA 24 2
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Input Controls
Source Document Design - Reasons
It reduces the likelihood of data recording errors
It increases the speed with which data can be recorded
It controls the work flow
It facilitates data entry into a computer system
For pattern recognition devices, it increases the speed and the accuracy
with which data can be read
It facilities subsequent reference checking
Discussion
Who should design the source document and when ?
© 2010 – CHANDRA YULISTIA, CISA 25 2
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Input Controls
Source Document Design - Guidelines
Preprint wherever possible
Provide titles, headings, notes and instructions
Use techniques for emphasis and to highlight differences
Arrange fields for ease of use
Use the “caption above fill-in area” approach for captions and data fields
When possible, provide multiple-choice answer to questions to avoid
omissions
Use tick mark or indicator values to identify field-size errors
Combine instructions with question
Space items appropriately on forms
Design for easy keying
Prenumber source documents
Conform to organizational standards
© 2010 – CHANDRA YULISTIA, CISA 26 2
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Input Controls
Data-Entry Screen Design
Screen Organization
Screen should be designed so they are uncluttered and symmetrically balanced
Data-entry Field Design
Data-entry fields should immediately follow their associated caption either in the
same line or, in the case of a repeating field, on several lines immediately below
the caption
Caption Design
Caption indicate the nature of the data to be entered in a field on a screen.
Consider the structure, size, font type, display density, format, alignment,
justification and spacing
Tabbing & Skipping
Avoid automatic skipping, use manual tabbing, maintain keying rhythm
© 2010 – CHANDRA YULISTIA, CISA 27 2
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Input Controls
Data-Entry Screen Design
Color
Data-entry screen color can be used to aid in locating a particular caption or data
item, to separate areas on the display, or to indicate a changed status.
Response Time
Response time during data entry is the interval that elapses between entry of a
data item and the system’s indication it is ready to accept a new data item.
Display Rate
Display rate is the rate at which characters or images on a screen are displayed
Prompting and Help Facilities
A prompting facility provides immediate advice or information about actions
users should take when they work with data-entry screen
© 2010 – CHANDRA YULISTIA, CISA 28 2
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Input Controls
Data Code Controls
Data Coding Errors Types
Addition 87942 879142
Truncation 87942 8792
Transcription 87942 81942
Transposition 87942 78942
Double Transposition 87942 84972
Data Coding Errors Factors
Length of the code
Alphabetic / numeric mix
Choice of characters
Mixing uppercase / lowercase fonts
Predictability of character sequence
© 2010 – CHANDRA YULISTIA, CISA 29 2
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Input Controls
Check Digits
A check digit is a redundant digit(s) added to a code that enables the
accuracy of other characters in the code to be checked.
Batch Controls
Types of batch
Physical - constitute a physical unit
Logical - bound together on some logical basis
Type of control in batch
Financial Totals
Hash Totals
Document / record counts
© 2010 – CHANDRA YULISTIA, CISA 30 3
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Input Controls
Validation of Data Input
Field Checks
Missing data or blanks
Alphabetic or numeric
Range
Set membership
Check digit
Master reference
Size
Format mask
Record Checks
Reasonableness
Valid sign-numerics
Size
Sequence check
Batch Checks
Control totals
Transaction type
Batch serial number
Sequence check
© 2010 – CHANDRA YULISTIA, CISA 31 3
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Input Controls
Audit Trails
Identity of the person (organization) who was the source of data
Identity of the person (organization) who entered the data into the
system.
Time and date when the data was captured
Identifier of the physical device used to enter the data into the system
Account or record to be updated by the transaction
Standing data to be updated by the transaction
Details of transaction
Number of physical or logical batch to which the transaction belongs
Time to key in a source document or an instruction at a terminal
Number of read errors made by an optical scanning device
Number of keying errors identified during verification
© 2010 – CHANDRA YULISTIA, CISA 32 3
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Processing
Controls
© 2010 – CHANDRA YULISTIA, CISA 33 3
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Processing Controls
Introduction
The processing subsystem is responsible for
computing, sorting, classifying, and summarizing data
Major components in processing subsystem
Central processor
Real/ virtual memory
Operating system
Application programs
© 2010 – CHANDRA YULISTIA, CISA 34 3
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Processing Controls
Processor Controls
Error detection and correction
The control unit might fetch an instruction from main memory, so
the control unit should reflects the instruction (perhaps multiple
times) & evaluate once again
The execution of an instruction fails. Various types of code can be
used
The data in a register is corrupted. Simple parity checks are often
used to detect an error in a register
Multiple execution states
Supervisor State
Problem State
Timing Controls
Component Replication
© 2010 – CHANDRA YULISTIA, CISA 35 3
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Processing Controls
Memory Controls
The real memory of a computer system comprises the fixed
amount of primary storage in which programs/ data must reside
for them to be executed/ referenced by the central processor
Error Detection & Correction
Access Controls
© 2010 – CHANDRA YULISTIA, CISA 36 3
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Processing Controls
Operating System integrity
The operating system is the set of programs
implemented in software, firmware, or hardware
that permits sharing & use of resources within a
computer system
Auditors often pay little attention to the
evaluation of operating system controls
Nature of a reliable operating system
© 2010 – CHANDRA YULISTIA, CISA 37 3
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Processing Controls
Penetration
technique
Explanation
Browsing Involves searching residue to gain unauthorized access to information
Masquerading Involves carrying out unauthorized activities by impersonating a legitimate
user of the system/ impersonating the system itself
Piggybacking Involves intercepting communications between the operating system and
the user still is connected to the system but is inactive
Between-lines entry A penetrator takes advantage of the time during which a legitimate user still
is connected to the system but is inactive
Spoofing A penetrator fools users into thinking they are interacting with the operating
system
Backdoors/ trapdoors A backdoor/ trapdoor allows a user to employ the facilities of the operating
system without being subject to the normal controls
Trojan horse Users execute a program written by the penetrator
Operating System Threats
© 2010 – CHANDRA YULISTIA, CISA 38 3
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Processing Controls
Integrity Flaw Explanation
Incomplete parameter
validation
The system doesn’t check the validity of all attributes of a user’s request
Inconsistent parameter
validation
The system applies different validation criteria to the same construct within
the system
Implicit sharing of data The operating system uses a common area to service two/ more user
processes
Asynchronous
validation
If the operating system permits asynchronous processes. Users take
advantage of timing inadequacies to violate integrity
Inadequate access
control
The operating system performs incomplete checking, or one part of the
system assumes another part has performed the checking
Violable limits System documentation states limits, e.g., the maximum size of a buffer
Operating System Integrity Flaw
© 2010 – CHANDRA YULISTIA, CISA 39 3
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Processing Controls
Application Software Controls - Validation checks
Level of
check
Type of check Explanation
Field Overflow Can occur if a field used for computation isn’t
zeroized initially, some error in computation
occurs, or unexpected high values occurs
Range An allowable value range can apply to a field
Record Reasonableness The contents of one field can determine the
allowable value for another
Sign The contents of one field might determine
which sign is valid for a numeric field
File Crossfooting Separate control totals can be developed for
related fields & crossfooted at the end of a
run
Control totals Run-to-run control totals can be developed &
compared with the results of a run
© 2010 – CHANDRA YULISTIA, CISA 40 4
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Processing Controls
Application Software Controls - Programming style
Handle rounding correctly
Print run-to-run control totals
Minimize human intervention
Understand hardware/ software numerical hazards
Use redundant calculations
Avoid closed routines
© 2010 – CHANDRA YULISTIA, CISA 41 4
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Database
Controls
© 2010 – CHANDRA YULISTIA, CISA 42 4
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Database Controls
Introduction
The database subsystem is responsible for defining, creating,
modifying, deleting, and reading data in an information system
The major components in the database subsystem
The data base management system
The applications programs
The central processor & primary storage
The storage media
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Database Controls
Access Controls
Access controls in the database subsystem seek to prevent
unauthorized access to and use of data
Discretionary access controls
In the database subsystem, discretionary access controls can vary
considerably
Mandatory access controls
Under this approach, resources are assigned a classification level &
users are assigned a clearance level
User access to a resource is governed by a security policy
© 2010 – CHANDRA YULISTIA, CISA 44 4
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Database Controls
Integrity Controls
Established to maintain the accuracy,
completeness, & uniqueness of instances of the
constructs used within the conceptual modelling/
data modelling approach
Used to represent the real-world phenomena
about which data is to be stored in the data
subsystem
Controls
Entity Relationship Model Integrity Constraints
Relational Data Model Integrity Constraint
Object Data Model Constraint
© 2010 – CHANDRA YULISTIA, CISA 45 4
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Database Controls
Application Software Controls
Update Protocols
Sequence check transaction & master files
Ensure all records on files are processed
Process multiple transaction for a single record in the correct order
Maintain a suspense account
Report Protocols
Print control data for internal tables (standing data)
Print run-to-run control totals
Print suspense account entries
© 2010 – CHANDRA YULISTIA, CISA 46 4
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Database Controls
Concurrency Controls - Deadlock
Process P Process Q
Data
Resource
1
Data
Resource
2
Time t Time t
Time t+1 Time t+1
© 2010 – CHANDRA YULISTIA, CISA 47 4
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Topic Seven
Output
Controls
© 2010 – CHANDRA YULISTIA, CISA 48 4
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Output Controls
Introduction
Output subsystem determine the content of data that will be provided to
users, the ways data will be formatted and presented to users, and the ways
data will be prepared for and routed to user.
Some issues
Inference Controls
Batch Output and Distribution Controls
Batch Report Design Controls
Online Output Production & Distribution Contols
Audit Trails
© 2010 – CHANDRA YULISTIA, CISA 49 4
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Output Controls
Inference Controls
Used to prevent compromise of statistical databases : Database from
which user can obtain only aggregate statistic rather than the values of
individual data item
Type of Compromise
Positive Compromise, whereby users determine that a person has a particular
attribute value
Negative Compromise, whereby users determine that a person does not have a
particular attribute value
Exact Compromise, whereby users determine the precise value of an attribute
possessed by a person
Approximate Compromise, whereby users determine within range the attribute
value possessed by a person
© 2010 – CHANDRA YULISTIA, CISA 50 5
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Output Controls
Inference Controls
Restriction Control
Limit the set of responses that will be provided to users to try to protect the
confidentiality of data about persons in the database
Types
Order Control
Relative Table Size Control
Query Set Overlap Control
Cell Suppression
Grouping or Rolling Control
Partitioning
© 2010 – CHANDRA YULISTIA, CISA 51 5
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Output Controls
Inference Controls
Perturbation Control
Giving some type of noise into the statistics calculated on the basis of records
retrieved from the database
Implemented Records-Based or Results-Based
Types
Records-Based
– Query Set Sampling
– Data Perturbation
– Data Swapping
Results-Based
– Put an error term after the true statistic has been calculated
© 2010 – CHANDRA YULISTIA, CISA 52 5
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Output Controls
Batch Output Production & Distribution Controls
Batch Output that is produced at some operation facility and subsequently
distributed to or collected by custodians or users of the output.
The production & distribution of batch output are controlled to ensure that
accurate, complete and timely output is provided only to authorized
custodians or users.
Controls are implemented in various phases in the production and
distribution of batch output
© 2010 – CHANDRA YULISTIA, CISA 53 5
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Output Controls
Batch Output Production & Distribution Controls
Some Controls
Securing the storage of any special stationery used to produce batch output
Ensuring only authorized users are permitted to execute batch report
programs
Ensuring that the contents of spooling/printer files cannot be altered
Preventing unauthorized parties from viewing the contents of confidential
reports as they are printed
Collecting reports promptly to prevent their loss
Having client services staff to review batch output for obvious errors prior to
distribution to users
Ensuring batch output is distributed to the correct user
Having end users to review output for errors or irregularities,
Storing batch output securely
Determining an appropriate retention period for batch output
Shredding batch output when is no longer required
© 2010 – CHANDRA YULISTIA, CISA 54 5
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Output Controls
Batch Report Design Controls
Batch output reports can be designed to facilitate exercising effective
and efficient controls over them.
Some information need to be included in the report :
Report name
Time & date of production
Distribution list, including number of copies
Processing period covered
Program, including version number, that produce the report
Contact person
Security classification
Retention date
Method of destruction
Page heading
Page number
End-of-job marker
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Output Controls
Online Output Production & Distribution Controls
Online Output is output that is delivered electronically to the terminal
employed by a user to gain access to a system
The production & distribution of online output are controlled to ensure that
accurate, complete and timely output is provided only to authorized
custodians or users.
Controls are implemented in various phases in the production and
distribution of online output
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Output Controls
Online Output Production & Distribution Controls
Some Controls
Ensuring that the output that can be accessed online is authorized, accurate, and
complete
Ensuring that online output is distributed to the correct network address
Preserving the integrity of privacy of online output transmitted over
communication line
Checking that data has been received by the intended user
Determining whether the intended user has read and considered properly the
contents of online output
Ensuring that disposition of the online output is appropriate
Determining an appropriate retention period for online output
Deleting online output completely when is no longer required
© 2010 – CHANDRA YULISTIA, CISA 57 5
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Output Controls
Audit Trails
What output was presented to user
Who received the output
When the output was received
What actions were subsequently taken with output
Records of the resources consumed to produce various types of output
Discussion
How to control the data reporting tools ?
