Security is one of the most critical aspects of any enterprise platform. In ServiceNow, protecting sensitive data is not optional — it is mandatory. Organizations handle employee records, financial data, incident details, and confidential business information inside ServiceNow. To control who can access what, ServiceNow uses ACL (Access Control List) Security Rules. In this blog, we will explore ACLs, row-level security, column-level security, and condition-based access as part of a structured ServiceNow Course in Telugu.

What is an ACL in ServiceNow?

ACL stands for Access Control List. It is a security rule that determines whether a user can:

• Read a record

• Create a record

• Write (update) a record

• Delete a record

In simple terms, ACLs answer the question: “Does this user have permission to perform this operation on this data?”

ACLs are evaluated whenever a user tries to access data through:

• Forms

• Lists

• Service Portal

• APIs

• Scripts

If the ACL conditions are not met, access is denied.

Types of ACLs in ServiceNow

There are two main types of ACL security:

1. Row-Level Security (Record-Level ACL)

2. Column-Level Security (Field-Level ACL)

Understanding the difference between these two is very important.

Row-Level Security (Record-Level ACL)

Row-level security controls access to entire records in a table.

For example:

• A user can read only incidents assigned to their group.

• An employee can view only their own HR case records.

If a row-level ACL denies access, the user cannot see the record at all.

Row-level ACLs are defined on:

Table Name → Operation

Example:
incident → read
incident → write

These ACLs apply to the whole record.

Column-Level Security (Field-Level ACL)

Column-level security controls access to specific fields within a record.

For example:

• A user can see the incident record but cannot view the “Work Notes” field.

• Salary field in HR table is visible only to HR managers.

Field-level ACLs are defined on:

Table Name.Field Name → Operation

Example:
incident.short_description → read
incident.work_notes → write

If a field-level ACL denies access, that particular field is hidden or read-only, even if the user can access the record.

How ACLs Are Evaluated

When a user attempts to access data, ServiceNow checks ACL rules in a specific order:

1. Table-level ACL

2. Field-level ACL

3. Parent table ACL (if extended table)

If any ACL denies access, the operation fails.

ACL Components

Each ACL rule contains three main components:

1. Requires Role

2. Condition

3. Script

Let’s understand these in detail.

Requires Role

This is the simplest method. If a user has the required role, access is granted.

Example:
Only users with “itil” role can read incident records.

If the user does not have the role, access is denied.

Condition

Conditions are filter-based rules. You can define conditions similar to list filters.

Example:
Assigned to is (dynamic) Me

This ensures users can access only records assigned to them.

Conditions are useful for simple logic without scripting.

Script

Scripts provide advanced logic for complex scenarios.

For example:

• Allow write access only if record state is not Closed.

• Allow HR managers to access salary data only for employees in their department.

Scripts use JavaScript and provide full flexibility.

Best Practice: Use roles and conditions first. Use scripts only when necessary.

Example Scenario

Let’s say we want:

• Only ITIL users to read incidents.

• Users to edit incidents only if assigned to them.

• Work Notes visible only to support team.

Implementation:

1. Table ACL: incident → read → Requires Role: itil

2. Table ACL: incident → write → Condition: Assigned to is Me

3. Field ACL: incident.work_notes → read/write → Requires Role: itil

This combination ensures secure and controlled access.

Debugging ACL Issues

Sometimes users report that they cannot see certain records or fields. ServiceNow provides a useful tool called:

“Debug Security Rules”

By enabling security debugging, administrators can see:

• Which ACL was evaluated

• Which rule granted or denied access

• Why access was denied

This helps in quick troubleshooting.

ACLs in Extended Tables

ServiceNow tables often extend other tables.

Example:
Incident extends Task.

If an ACL exists on Task table, it may affect Incident table as well. Therefore, developers must carefully check parent table ACLs when troubleshooting access issues.

Performance Considerations

Too many complex ACL scripts can impact performance. Best practices include:

• Avoid heavy database queries inside ACL scripts

• Keep logic simple

• Use caching where possible

• Minimize unnecessary ACL duplication

Real-World Importance of ACLs

In enterprise environments, ACL misconfiguration can cause:

• Data leaks

• Compliance violations

• Unauthorized data modification

For example, if salary information becomes visible to all employees due to missing field-level ACL, it can create serious security issues.

Therefore, understanding ACL design is critical for ServiceNow developers and administrators.

Common Interview Questions

During interviews, candidates are often asked:

• What is the difference between row-level and field-level ACL?

• How does ACL evaluation order work?

• What are components of an ACL rule?

• How do you debug ACL issues?

• What is the impact of parent table ACLs?

Hands-on practice in a ServiceNow Course in Telugu helps learners confidently answer such scenario-based questions.

Conclusion

ACL Security Rules form the foundation of data protection in ServiceNow. Row-level ACLs control access to entire records, while column-level ACLs protect specific fields. Using roles, conditions, and scripts effectively ensures secure and compliant system behavior.

A structured ServiceNow Course in Telugu provides practical exposure to creating, testing, and debugging ACLs in real-time scenarios. Mastering ACL security not only strengthens your technical skills but also makes you a responsible and reliable ServiceNow professional.