Back to skill

Security audit

zhz-video-logo

Security checks for vulnerabilities and agentic risk

Overview

This video-watermarking skill needs review because its optional replacement mode can delete originals or overwrite another video despite its safety promises.

Keep backups, preview the batch, and use a separate output folder outside the source directory. Avoid --replace until destination collision checks and failure-safe replacement are implemented. The evidence supports a data-loss concern, not malicious intent.

Vulnerability Patterns
  • 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
  • Unauthorized Access and Privilege EscalationObtains permissions beyond the task's legitimate needs
Vulnerability Patterns
  • Behavioral ASTexec() Call, eval() Call, Dynamic Import
  • Taint TrackingDirect Taint Flow, Variable-Mediated Taint Flow, Credential Exfiltration Chain
  • MCP Least PrivilegeUnderdeclared Capability, Wildcard Permission, Missing Permission Declaration
  • MCP Tool PoisoningHidden Instructions, Unicode Deception, Parameter Description Injection
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
Findings (4)

Skill declares no tool scope ('permissions' or 'allowed-tools') but code capabilities were detected: env, file_read, file_write, shell.

Medium
Category
MCP Least Privilege
Confidence
70% confidence
Finding

Without declared permissions the skill's intent is opaque and cannot be validated.

Content

No source excerpt is available for this finding.

subprocess module call

Medium
Category
Dangerous Code Execution
Confidence
70% confidence
Finding

subprocess module calls execute external commands. Without careful input validation, this enables command injection.

Content

Scanner excerpt · scripts/video_logo.py (reported line 152)May include surrounding context.

python
def run(cmd):
    return subprocess.run(cmd, capture_output=True, text=True,
                          encoding="utf-8", errors="replace",
                          creationflags=CREATION_FLAGS)

Tainted flow: 'cmd' from os.environ.get (line 402, credential/environment) → subprocess.run (code execution)

Medium
Category
Data Flow
Confidence
65% confidence
Finding

Data from a source is assigned to a variable that is later passed to a sink, creating a variable-mediated taint flow.

Content

Scanner excerpt · scripts/video_logo.py (reported line 152)May include surrounding context.

python
def run(cmd):
    return subprocess.run(cmd, capture_output=True, text=True,
                          encoding="utf-8", errors="replace",
                          creationflags=CREATION_FLAGS)

Extension-changing replacement deletes the original before committing the output, contradicting the documented original-file safety guarantee.

Medium
Category
Excessive Agency
Confidence
99% confidence
Finding

When --replace changes the container extension, the code deletes the source before committing the validated output with os.replace. If that commit fails or execution is interrupted, the original is already gone; the replacement can also overwrite an existing same-stem destination file without checking, making batch processing capable of unintended data loss.

Content

No source excerpt is available for this finding.

Static analysis

No suspicious patterns detected.