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Security audit

sixel-email

Security checks for vulnerabilities and agentic risk

Overview

This skill provides a disclosed one-to-one email channel for an agent and its operator, with expected external API use and no hidden executable payload.

Install only if you want an agent to communicate through sixel.email. Configure SIXEL_API_URL only to a trusted service, guard SIXEL_API_TOKEN, review email bodies and attachments before sending, and run the optional background poller only when you want continuous heartbeat polling.

A.I.G

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

SkillSpector

Vulnerability Patterns
  • Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
  • Privilege EscalationExcessive Permissions, Sudo/Root Execution, Credential Access
  • Supply ChainUnpinned Dependencies, External Script Fetching, Obfuscated Code
  • Excessive AgencyUnrestricted Tool Access, Autonomous Decision Making, Scope Creep
Findings (2)

External Transmission

Medium
Category
Data Exfiltration
Confidence
60% 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 48)May include surrounding context.

Verify your connection:

bash
curl -fsSL "${SIXEL_API_URL:-https://sixel.email/v1}/inbox" \
  -H "Authorization: Bearer ${SIXEL_API_TOKEN}"

Missing User Warnings

Medium
Category
Not specified by scanner
Confidence
87% confidence
Finding

This markdown file documents sending email attachments and even demonstrates attaching a local build log, which can easily contain secrets, internal paths, or other sensitive data. While the file warns not to include secrets in email bodies, it does not give an equivalent warning for attachments in this section, so the description under-warns about a privacy-impacting behavior.

Content

No source excerpt is available for this finding.

Static analysis

No suspicious patterns detected.