Audit Objectives and Procedures in a Computer Operations Context January 27, 2005.
-
Upload
derrick-montgomery -
Category
Documents
-
view
214 -
download
0
Transcript of Audit Objectives and Procedures in a Computer Operations Context January 27, 2005.
Audit Objectives and Procedures in a
Computer Operations Context
January 27, 2005
2
STRUCTURING THE IT FUNCTION
Centralized data processing Database administrator Data processing manager/dept.
Data control Data preparation/conversion Computer operations Data library
3
Segregation of incompatible IT functions Systems development & maintenance
Participants End users IS professionals Auditors Other stakeholders
STRUCTURING THE IT FUNCTION
4
Segregation of incompatible IT functions Objectives:
Segregate transaction authorization from transaction processing
Segregate record keeping from asset custody Divide transaction processing steps among
individuals to force collusion to perpetrate fraud
STRUCTURING THE IT FUNCTION
5
Segregation of incompatible IT functions
Separating systems development from computer operations
STRUCTURING THE IT FUNCTION
6
Segregation of incompatible IT functions Separating DBA from other functions
DBA is responsible for several critical tasks: Database security Creating database schema and
user views Assigning database access authority to users Monitoring database usage Planning for future changes
STRUCTURING THE IT FUNCTION
7
STRUCTURING THE IT FUNCTION
Segregation of incompatible IT functions Alternative 1: segregate systems analysis
from programming Two types of control problems from this approach:
Inadequate documentation Is a chronic problem. Why? Not interesting Lack of documentation provides job security Assistance: Use of CASE tools
Potential for fraud Example: Salami slicing, trap doors
8
Segregation of incompatible IT functions Alternative 2: segregate systems
development from maintenance Two types of improvements from
this approach:1. Better documentation standards
Necessary for transfer of responsibility2. Deters fraud
Possibility of being discovered
STRUCTURING THE IT FUNCTION
9
Segregation of incompatible IT functions Segregate data library from operations
Physical security of off-line data files Implications of modern systems on use of data
library: Real-time/online vs. batch processing Volume of tape files is insufficient to justify full-time
librarian Alternative: rotate on ad hoc basis
Custody of on site data backups Custody of original commercial software and licenses
STRUCTURING THE IT FUNCTION
10
Segregation of incompatible IT functions Audit objectives
Risk assessment Verify incompatible areas are properly
segregated How would an auditor accomplish this objective?
Verify formal vs. informal relationships exist between incompatible tasks Why does it matter?
STRUCTURING THE IT FUNCTION
11
Segregation of incompatible IT functions Audit procedures: Obtain and review security policy Verify policy is communicated Review relevant documentation (org. chart, mission
statement, key job descriptions) Review systems documentation and maintenance
records (using a sample) Verify whether maintenance programmers are also
original design programmers Observe segregation policies in practice Review operations room access log Review user rights and privileges
STRUCTURING THE IT FUNCTION
12
The distributed model Distributed Data Processing (DDP)
Definition Alternative A: centralized Alternative B: decentralized / network
STRUCTURING THE IT FUNCTION
13
The distributed model Risks associated with DDP
Inefficient use of resources Mismanagement of resources by end users Hardware and software incompatibility Redundant tasks
Destruction of audit trails Inadequate segregation of duties Hiring qualified professionals
Increased potential for errors Programming errors and system failures
Lack of standards
STRUCTURING THE IT FUNCTION
14
The distributed model Advantages of DDP
Cost reduction End user data entry vs. data control group Application complexity reduced Development and maintenance costs reduced
Improved cost control responsibility IT critical to success then managers must
control the technologies Improved user satisfaction
Increased morale and productivity Backup flexibility
Excess capacity for DRP
STRUCTURING THE IT FUNCTION
15
Controlling the DDP environment Need for careful analysis Implement a corporate IT function
Central systems development Acquisition, testing, and implementation of
commercial software and hardware User services
Help desk: technical support, FAQs, chat room, etc.
Standard-setting body Personnel review
IT staff
STRUCTURING THE IT FUNCTION
16
Controlling the DDP environment Audit objectives:
Conduct a risk assessment Verify the distributed IT units employ entity-
wide standards of performance that promotes compatibility among hardware, operating software, applications, and data
STRUCTURING THE IT FUNCTION
17
Controlling the DDP environment Audit procedures:
Verify corporate policies and standards are communicated
Review current organization chart, mission statement, key job descriptions to determine if any incompatible duties exist
Verify compensating controls are in place where incompatible duties do exist
Review systems documentation Verify access controls are properly
established
STRUCTURING THE IT FUNCTION
18
Computer center controls Physical location
Avoid human-made and natural hazards Example: Chicago Board of Trade
Construction Ideally: single-story, underground utilities,
windowless, use of filters If multi-storied building, use top floor (away from
traffic flows, and potential flooding in a basement) Access
Physical: Locked doors, cameras Manual: Access log of visitors
THE COMPUTER CENTER
19
Computer center controls
THE COMPUTER CENTER
Air conditioning Especially mainframes Amount of heat even from a group of PCs
Fire suppression Automatic: usually sprinklers
Gas, such as halon, that will smother fire by removing oxygen can also kill anybody trapped there
Sprinklers and certain chemicals can destroy the computers and equipment
Manual methods Power supply
Need for clean power, at a acceptable level Uninterrupted power supply
20
Computer center controls Audit objectives Verify physical security controls are reasonable Verify insurance coverage is adequate Verify operator documentation is adequate in
case of failure Audit procedures Tests of physical construction Tests of fire detection Tests of access control Tests of backup power supply Tests for insurance coverage Tests of operator documentation controls
THE COMPUTER CENTER
21
Controlling access privileges Audit objectives
Verify that access privileges are granted in a manner consistent with the need to separate incompatible functions and is in accordance with organizational policy
Audit procedures Review polices for separating incompatible functions Review privileges for groups to determine if access
rights are appropriate for jobs. “need to know” Do privileged employees undergo security clearance? Do employee records indicate that employees
acknowledge their responsibility to maintain confidentiality?
Review users’ permitted logon times
SYSTEM-WIDE CONTROLS
22
Password control Common forms of contra-security behavior Reusable passwords One-time passwords Password policy
Audit objectives Ensure that the organization has an adequate and effective
password policy
Audit procedures Verify that users are required to have passwords Verify that new users are properly trained in password use Determine if procedures are in place to identify weak
passwords Assess the adequacy of password standards such a length
and expiration interval Review the account lockout policy and procedure
SYSTEM-WIDE CONTROLS
23
Password Policy
Proper Dissemination – Promote it, use it during employee training or orientation, and find ways to continue to raise awareness within the organization.
Proper Length: Use at least 8 characters. The more characters, the more difficult to guess or crack. Eight characters is an effective length to prevent guessing, if combined with below.
Proper Strength: Use alphabet (letters), numbers (at least 1), and special characters (at least 1). The more non-alpha, the harder to guess or crack. Make them case sensitive and mix upper and lower case. A “Strong” password for any critical access or key user. Password CANNOT contain a real word in the content.
Proper Access Levels or Complexity: Use multiple levels of access requiring multiple passwords. Use a password matrix of data to grant read-only, read/write, or no access per data field per user. Use biometrics {such as fingerprints, voice prints}. Use supplemental access devices, such as smart cards, or beeper passwords in conjunction with remote logins. Use user-defined procedures.
Proper Timely Changes: At regular intervals, make employees change their passwords.
Proper Protection: Prohibit the sharing of passwords or “post-its” with passwords located near one’s computer.
Proper Deletion: Require the immediate deletion of accounts for terminated employees, to prevent an employee from being able to perpetrate adverse activities.
24
E-mail risks Spoofing Spamming Chain letters Urban legends Hoax virus warnings Flaming Malicious attachments (e.g., viruses)
SYSTEM-WIDE CONTROLS
25
Malicious objects risk Virus Worm Logic bomb Back door / trap door Trojan horse Potential control procedures
Audit Objective Verify that effective management policies and procedures are in
place to prevent the introduction and spread of destructive objects Audit Procedures
Through interviews with personnel, determine if they have been educated regarding risky computing practices
Review procedures to determine if disks or CDs that could contain viruses are routinely transferred between workgroups
Verify that system administrators routinely scan workstations, file servers, and email servers for viruses
Verify that new software is tested on standalone workstations prior to being implemented on the host or network server
Verify that antivirus software is updated at regular intervals and downloaded to individual workstations
SYSTEM-WIDE CONTROLS
26
Controlling electronic audit trails Keystroke monitoring (keystroke log) Event monitoring (key events log) Audit trail objectives
Detecting unauthorized access Reconstructing events Personal accountability
Implementing an audit trail
SYSTEM-WIDE CONTROLS
27
Controlling electronic audit trails Audit objective
Verify adequate audit trails and logs
Audit procedures O/S audit log viewer ACL extraction of log data (see list) Sample organizational security group’s
records
SYSTEM-WIDE CONTROLS
28
Disaster recovery planning
Types of disaster Natural: fire, flood, tornado Human-Made: sabotage, error System failure: power outage, drive
failure, crash
SYSTEM-WIDE CONTROLS
29
Disaster recovery planning
Critical applications identified and ranked
Create a disaster recovery team with responsibilities
SYSTEM-WIDE CONTROLS
30
Disaster recovery planning Site backup
“Hot site” – Recovery Operations Center
“Cold site” – empty shell Mutual aid pact Internally provided backup Other options
SYSTEM-WIDE CONTROLS
31
Disaster recovery planning Hardware backup
(if NOT a hot site) Software backup: operating system
(if NOT a hot site) Software backup: application
software(based on critical application step)
SYSTEM-WIDE CONTROLS
32
Disaster recovery planning Data backup Supplies (on site) Documentation (on site)
User manuals System and software technical
manuals
Test!
SYSTEM-WIDE CONTROLS
33
Disaster Recovery Plan
1. Critical Applications – Rank critical applications so an orderly and effective restoration of computer systems is possible.
2. Create Disaster Recovery Team – Select team members, write job descriptions, describe recovery process in terms of who does what.
3. Site Backup – a backup site facility including appropriate furniture, housing, computers, and telecommunications. Another valid option is a mutual aid pact where a similar business or branch of same company swap availability when needed.
4. Hardware Backup – Some vendors provide computers with their site – known as a hot site or Recovery Operations Center. Some do not provide hardware – known as a cold site. When not available, make sure plan accommodates compatible hardware (e.g., ability to lease computers).
5. System Software Backup – Some hot sites provide the operating system. If not included in the site plan, make sure copies are available at the backup site.
6. Application Software Backup – Make sure copies of critical applications are available at the backup site
7. Data Backup – One key strategy in backups is to store copies of data backups away from the business campus, preferably several miles away or at the backup site. Another key is to test the restore function of data backups before a crisis.
8. Supplies – A modicum inventory of supplies should be at the backup site or be able to be delivered quickly.
9. Documentation – An adequate set of copies of user and system documentation.
10. TEST! – The most important element of an effective Disaster Recovery Plan is to test it before a crisis occurs, and to test it periodically (e.g., once a year).
34
Disaster recovery planning Audit objectives
Verify management’s DRP is adequate Audit procedures
Verify a second-site backup is adequate Review the critical application list for completeness Verify backups of application software are stored off-
site Verify that critical data files are backed up and
readily accessible to DRP team Verify resources of supplies, documents, and
documentation are backed up and stored off-site Verify that members listed on the team roster are
current employees and that they are aware of their responsibilities
SYSTEM-WIDE CONTROLS
35
Fault tolerance Definition 44% of time IS unavailable is due to system failures! Controls
Redundant systems or parts RAID
UPS Multiprocessors
Audit objective To ensure the organization is employing an appropriate
level of fault tolerance Audit procedures
Verify proper level of RAID devices Review procedures for recovery from system failure Verify boot disks are secured
SYSTEM-WIDE CONTROLS