Security audit

CORS Tester

Security checks for vulnerabilities and agentic risk

Overview

This is a straightforward CORS testing skill with user-directed network probes and config generation, and I found no hidden persistence, credential access, or deceptive behavior.

Install only if you need a CLI-style CORS tester. Expect it to contact the URLs you provide, including multiple audit probes, and avoid running it against third-party systems without permission. Treat generated server configuration as a draft: review it, validate it with the target framework's config checker, and do not feed attacker-controlled values into the generator.

A.I.G

Vulnerability Patterns

Insecure Skill Coding PracticesFinds exploitable flaws such as hardcoded secrets or command injection
Skill Instruction HijackingAlters the agent's session goals or safety constraints when the skill loads
Agent Memory PoisoningWrites attacker-controlled rules into memory that affect later sessions
Remote Payload Retrieval and ExecutionFetches external code whose behavior can change after review
Embedded Malicious CodeShips malicious scripts inside the skill and executes them locally

Findings (2)

T09 · Insecure Skill Coding Practices

Warning

Location: scripts/cors_tester.py:225
Finding: Unsafe Input Interpolation in Generated Server Configurations
Content: View full analysis
Header set Access-Control-Allow-Origin "{o}" Header set Access-Control-Allow-Methods "{m}" Header set Access-Control-Allow-Headers "{h}" {"Header set Access-Control-Allow-Credentials true" if c else ""} Header set Access-Control-Max-Age "{ma}" """), ``` ```python "rails": lambda o, m, h, c, ma: dedent(f"""\ # config/initializers/cors.rb Rails.application.config.middleware.insert_before 0, Rack::Cors do allow do origins {', '.join(f"'{x.strip()}'" for x in o.split(','))} resource '*', headers: :any, methods: [{', '.join(f':{x.strip().lower()}' for x in m.split(','))}], credentials: {'true' if c else 'false'}, max_age: {ma} end end"""), } def cmd_config(args): framework = args.framework if framework not in ...[truncated 3037 chars]
Remediation: View remediation

T09 · Insecure Skill Coding Practices

Warning

Location: scripts/cors_tester.py:25
Finding: Case-Sensitive CORS Header Parsing Can Produce Audit False Negatives
Content: View full analysis
Remediation: View remediation

SkillSpector

Vulnerability Patterns

Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
MCP Least PrivilegeUnderdeclared Capability, Wildcard Permission, Missing Permission Declaration
Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
Privilege EscalationExcessive Permissions, Sudo/Root Execution, Credential Access
Supply ChainUnpinned Dependencies, External Script Fetching, Obfuscated Code

Findings (6)

Undeclared Tool Scope

Medium

Category: MCP Least Privilege
Confidence: 88% confidence
Finding: The skill clearly describes and demonstrates live network access to arbitrary URLs, but it declares no explicit tool scope or permissions. In an agent environment, this creates a capability mismatch that can enable unintended outbound requests and weakens policy enforcement, review, and user awareness about network use.
Content: No source excerpt is available for this finding.

External Transmission

Medium

Category: Data Exfiltration
Confidence: 50% confidence
Finding: Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
Content: Scanner excerpt · SKILL.md (reported line 14)May include surrounding context.
bash
# Test CORS headers on a URL python3 scripts/cors_tester.py test https://api.example.com/data --origin https://myapp.com # Test preflight (OPTIONS) request python3 scripts/cors_tester.py preflight https://api.example.com/data --origin https://myapp.com --method POST --header "Content-Type"

External Transmission

Medium

Category: Data Exfiltration
Confidence: 50% confidence
Finding: Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
Content: Scanner excerpt · SKILL.md (reported line 17)May include surrounding context.
bash
# Test CORS headers on a URL python3 scripts/cors_tester.py test https://api.example.com/data --origin https://myapp.com # Test preflight (OPTIONS) request python3 scripts/cors_tester.py preflight https://api.example.com/data --origin https://myapp.com --method POST --header "Content-Type"

External Transmission

Medium

Category: Data Exfiltration
Confidence: 50% confidence
Finding: Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
Content: Scanner excerpt · SKILL.md (reported line 23)May include surrounding context.
bash
# Test CORS headers on a URL python3 scripts/cors_tester.py test https://api.example.com/data --origin https://myapp.com # Test preflight (OPTIONS) request python3 scripts/cors_tester.py preflight https://api.example.com/data --origin https://myapp.com --method POST --header "Content-Type"

Missing User Warnings

Low

Category: Not specified by scanner
Confidence: 78% confidence
Finding: This code performs outbound HTTP requests to user-specified targets, sending request metadata such as the supplied Origin header. While the script's purpose is testing CORS, the code itself does not include an explicit warning, confirmation, or disclosure that it will contact remote servers and transmit these values.
Content: No source excerpt is available for this finding.

Missing User Warnings

Low

Category: Not specified by scanner
Confidence: 88% confidence
Finding: The audit command automatically sends several test requests, including origins like 'https://evil.com' and a preflight OPTIONS probe, to the target URL. Although this behavior aligns with the audit feature, there is no clear user warning in code comments or CLI help that the tool will actively probe the remote service in this way.
Content: No source excerpt is available for this finding.