Agentless scanning has rapidly become one of the most important techniques in cloud security. As organizations move toward multi-cloud, ephemeral infrastructure, serverless architectures, containers, and continuous deployment, traditional agent-based scanners often fall short. They can’t easily be installed on managed services, short-lived compute resources, or immutable infrastructure patterns.

Agentless scanning solves this visibility problem by analyzing cloud APIs, configurations, metadata, and runtime states without requiring agents or software to be installed on the underlying resources.

But while agentless scanning is powerful, it must be implemented carefully to avoid blind spots, credential risks, performance issues, and misinterpretation of cloud context.

This guide outlines the best practices for effective and secure agentless scanning across AWS, Azure, GCP, and Kubernetes environments.

What Is Agentless Scanning?

Agentless scanning is a security technique that inspects cloud environments and workloads through cloud provider APIs, snapshots, or metadata services—without deploying agents inside VMs, containers, or serverless functions.

Agentless scanners typically collect:

• IAM configurations
• Network exposure
• Storage permissions
• Container image details
• Runtime metadata
• Kubernetes manifests
• Cloud activity logs
• Vulnerability snapshots (via EBS/CloudDisk copies)
• Serverless & managed service configurations

This enables broad, immediate visibility into cloud security posture

Benefits of Agentless Scanning

• Faster onboarding (minutes, not weeks)
• No installation overhead on hosts
• Visibility into managed services (serverless, DBaaS, FaaS)
• Lower operational friction for DevOps teams
• Works in immutable & ephemeral environments
• Centralized scanning without fleet management
• Better for compliance & audits due to consistent coverage

However, agentless scanning is not a silver bullet. It must work alongside other techniques (like runtime agents, eBPF, and sidecar scanning) for full coverage.

Agentless Scanning Best Practices for Cloud Security

1. Use Least-Privilege IAM Roles for Scanning Access

Cloud scanners require broad API visibility—but not full admin rights.

Best Practices:

• Create dedicated scanner roles with scoped permissions.
• Enforce read-only, non-mutating API access.
• Use service control policies (SCPs) to restrict privilege escalation.
• Regularly audit and rotate scanner IAM roles.
• Apply conditional IAM policies to restrict resource types, accounts, and regions.

Never use overly permissive AdministratorAccess or wildcard * permissions.

2. Analyze Cloud Configurations Continuously, Not Periodically

Cloud environments change by the minute due to automation and auto-scaling.

Best Practices:

• Trigger agentless scans on:
  • IAM policy changes
  • VPC/network updates
  • New bucket/container/database creation
  • CI/CD deployments
  • Infrastructure-as-Code merges
• Use event-driven scanning (CloudTrail, EventBridge, Azure Activity Logs, GCP Audit Logs)
• Enable scheduled full posture scans (e.g., hourly or daily)

Continuous scanning reduces detection time for misconfigurations like public storage buckets or overly permissive roles.

3. Scan Snapshots (EBS, Azure Disk, GCP Persistent Disk) for Vulnerabilities

Agentless vulnerability detection often relies on scanning snapshots of disks or volumes.

Best Practices:

• Create ephemeral snapshots only during scanning windows
• Encrypt snapshots by default
• Automatically delete snapshots after analysis
• Enforce strict IAM around snapshot creation and access
• Validate that snapshots contain only necessary metadata, not excessive sensitive data

This technique enables vulnerability analysis of workloads you cannot modify (legacy apps, immutable images).

4. Avoid Credential Sprawl—Centralize Scanning Through a Broker

Distributing access keys or scanning credentials increases the attack surface.

Best Practices:

• Use a central credential broker (IAM Identity Center, GCP Service Accounts, Azure Entra ID)
• Avoid storing long-lived credentials in CI, scripts, or pipelines
• Prefer STS temporary credentials or AssumeRole flows
• Enable MFA and session policies for privileged access

The scanner should be the only system with required privileges.

5. Prioritize Identity & Access Misconfigurations First

80%+ of cloud breaches stem from identity issues (over-permissive roles, exposed keys, privilege escalation paths).

Agentless scanning should detect:

• IAM roles with wildcard permissions
• Trust policies allowing cross-account hijacking
• Publicly exposed access keys
• Excessive service account privileges (Kubernetes, GCP)
• Misconfigured IAM roles for serverless functions
• Abusable privilege escalation chains

Identity is the single most important attack vector in cloud environments.

6. Integrate Agentless Scanning with Infrastructure-as-Code (IaC)

Agentless scanning finds issues in running cloud environments, but IaC scanning prevents them before deployment.

Best Practices:

• Enforce IaC checks on PRs and CI/CD merges
• Compare IaC definitions to actual cloud state (detect drift)
• Use agentless scanning to detect runtime drift caused by manual changes
• Block deployments that introduce high-risk misconfigurations

Shift-left + agentless scanning closes both pre-deployment and post-deployment gaps.

7. Combine Agentless Scanning with Network Metadata Analysis

Agentless tools should identify:

• Public-facing IPs / load balancers
• Open security groups
• Unrestricted inbound/outbound rules
• Shadow VPCs or misconfigured subnets
• Orphaned security groups exposing dormant infrastructure

Focus on exposure, not just theoretical vulnerabilities.

8. Don’t Rely Solely on Agentless Scanning—Pair with Runtime Controls

Agentless scanning provides visibility, not runtime protection.

Missing from agentless-only systems:

• In-process threat detection
• Lateral movement detection
• eBPF-based runtime signals
• Memory or syscall-level insights
• Active container runtime monitoring

Best Practices:

• Use agentless scanning for posture
• Use agents/eBPF for runtime anomalies
• Use CNAPP platforms for unified visibility

Defense-in-depth prevents blind spots.

9. Ensure Cross-Account and Multi-Cloud Coverage

Agentless scanning must extend across:

• Production, staging, and dev accounts
• Shadow or abandoned cloud accounts
• Multi-cloud environments (AWS + Azure + GCP)
• Identity boundaries (Azure AD tenants, AWS Organizations)

Centralized scanning reduces gaps where attackers often hide.

10. Use Agentless Scanning to Detect Secrets, Tokens & Keys

Secrets often leak into:

• IAM instance profiles
• Container environment variables
• Lambda configuration
• Disk volumes
• Cloud metadata services

Agentless scanning can surface:

• Hardcoded secrets
• Exposed tokens
• Leaked SSH keys
• Misconfigured KMS policies

Secrets should be remediated through centralized secret management (AWS Secrets Manager, HashiCorp Vault, Azure Key Vault).

Top Security Risks of Agentless Scanning (and How to Mitigate Them)

1. Overprivileged Scanner IAM Roles

Use least privilege & continuous IAM review.

2. Snapshot Data Leakage

Encrypt + delete snapshots immediately after use.

3. Multi-Cloud Credential Mismanagement

Use short-lived credentials and centralized broker systems.

4. Race Conditions or Stale Data

Use event-driven scanning to detect real-time changes.

5. Blind Spots in Runtime Behavior

Pair agentless posture scanning with runtime telemetry.

Conclusion

Agentless scanning is a powerful, fast, and scalable way to secure cloud environments—especially in highly dynamic, ephemeral, and serverless architectures. When combined with least-privilege IAM, continuous scanning, IaC integration, and runtime monitoring, it dramatically improves cloud security posture.

Agentless scanning alone is not enough—but as a core component of a modern cloud-native security strategy, it provides unmatched visibility and reduces operational burden across DevOps, platform engineering, and security teams.