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Security audit

Thunderbird

Security checks for vulnerabilities and agentic risk

Overview

This skill is a disclosed local Thunderbird mail search tool, but users should treat its email and attachment access as sensitive.

Install only if you want an agent to inspect local Thunderbird mail. Use the narrowest profile, account, folder, and date filters possible; avoid printing full bodies or JSON in shared logs; save attachments only to an intended location; and do not open unknown attachments with the default app unless you accept the normal email-attachment malware risk.

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
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
  • Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
  • Excessive AgencyUnrestricted Tool Access, Autonomous Decision Making, Scope Creep
  • MCP Least PrivilegeUnderdeclared Capability, Wildcard Permission, Missing Permission Declaration
  • MCP Tool PoisoningHidden Instructions, Unicode Deception, Parameter Description Injection
Findings (15)

Hidden Instructions

High
Category
Prompt Injection
Confidence
60% confidence
Finding

Hidden instructions were detected in comments or invisible text. These could contain malicious directives. Manual review is recommended.

Content

Scanner excerpt · README.md (reported line 1)May include surrounding context.

md
# Thunderbird Skill for OpenClaw

Search and inspect local Mozilla Thunderbird mail storage directly from disk (mbox and Maildir), with filters for account, folder, sender, recipient, subject, body, unread state, time ranges, and attachments.

Ae1

High
Category
analysis-evasion
Confidence
100% confidence
Finding

Referenced artifact was not completely inspected

Content

Scanner excerpt · SKILL.md (reported line 14)May include surrounding context.

md
If the current working directory is not the skill directory, resolve `scripts/search_thunderbird.py` relative to this `SKILL.md` location before running it.

Context-Inappropriate Capability

High
Category
Not specified by scanner
Confidence
96% confidence
Finding

Instructing the agent to open attachments with the system default app can cause untrusted email attachments to be executed or rendered by vulnerable local software. Since email attachments are a common malware delivery vector, auto-launch guidance is especially dangerous in a mail-inspection skill.

Content

No source excerpt is available for this finding.

Missing User Warnings

Medium
Category
Not specified by scanner
Confidence
93% confidence
Finding

This markdown file documents the --save-attachments behavior and provides an example command that writes attachment files to a local output directory. The description does not include any warning that this operation creates files on disk and may handle sensitive email content, which is a user-impacting behavior covered by the markdown warning requirement.

Content

No source excerpt is available for this finding.

Undeclared Tool Scope

Medium
Category
MCP Least Privilege
Confidence
90% confidence
Finding

The skill directs the agent to read local mail data, inspect environment-dependent profile locations, and save attachments to disk, but it declares no explicit tool scope or permission boundaries. That mismatch increases the chance an agent can access sensitive files or write extracted content without clear authorization controls.

Content

No source excerpt is available for this finding.

Missing User Warnings

Medium
Category
Not specified by scanner
Confidence
88% confidence
Finding

The skill is designed to inspect local Thunderbird mail, which inherently contains sensitive personal and business communications, but the documentation lacks an explicit privacy warning or consent gate. Without that framing, an agent may over-collect or reveal email content and metadata more broadly than the user intended.

Content

No source excerpt is available for this finding.

Ssd 3

Medium
Category
Not specified by scanner
Confidence
88% confidence
Finding

Reading and summarizing local email bodies and attachments creates a direct path to disclose highly sensitive communications, credentials, invoices, legal content, or personal data. In context, the capability is aligned with the skill's purpose, but it still needs privacy gating because the source material is unusually sensitive.

Content

No source excerpt is available for this finding.

Ssd 3

Medium
Category
Not specified by scanner
Confidence
90% confidence
Finding

The default behavior instructs the agent to summarize mailbox path, date, sender, recipient, subject, and body preview, which can expose private email data even when only coarse search help is needed. Because these fields are sensitive and often enough to infer confidential matters, broad default disclosure is risky.

Content

No source excerpt is available for this finding.

Ssd 3

Medium
Category
Not specified by scanner
Confidence
93% confidence
Finding

The attachment workflow permits extracting, reading, summarizing, saving, and opening files from email, which can disclose sensitive documents and increase the risk of interacting with malicious content. Attachments are both privacy-sensitive and a common malware vector, so combining data access with external opening makes this materially more dangerous.

Content

No source excerpt is available for this finding.

Description-Behavior Mismatch

Medium
Category
Not specified by scanner
Confidence
94% confidence
Finding

The skill's stated purpose is reading and searching Thunderbird mail storage, but the attachment policy expands into opening extracted files with external applications. That broadens the attack surface from passive inspection to active execution of untrusted content, including attachment-triggered exploits in local applications.

Content

No source excerpt is available for this finding.

Description-Behavior Mismatch

Medium
Category
Not specified by scanner
Confidence
98% confidence
Finding

The skill is described as reading and searching Thunderbird mail, but it also creates directories and writes attachment contents to arbitrary user-specified paths via --save-attachments. That expands the capability from read-only inspection to file export, increasing the risk of unintended data exfiltration or unauthorized persistence of sensitive email attachments on disk.

Content

No source excerpt is available for this finding.

Missing User Warnings

Medium
Category
Not specified by scanner
Confidence
90% confidence
Finding

The code writes attachment files to disk silently once the flag is provided, without any additional disclosure in output or runtime confirmation that new files will be created. This can leave sensitive artifacts on disk in locations the user or calling agent may not anticipate, especially because filenames are preserved and collisions are resolved automatically.

Content

No source excerpt is available for this finding.

Context-Inappropriate Capability

Medium
Category
Not specified by scanner
Confidence
92% confidence
Finding

Enabling attachment export in a skill whose stated purpose is only search/read access violates the principle of least privilege and broadens the operational scope beyond what users would reasonably expect. In a mail-analysis context, attachments often contain highly sensitive data, so export functionality materially increases privacy and exfiltration risk.

Content

No source excerpt is available for this finding.

Missing User Warnings

Medium
Category
Not specified by scanner
Confidence
86% confidence
Finding

The script can output complete message bodies, senders, recipients, and subjects to stdout or JSON via --show-body and --json, which may expose sensitive local mail data. The file describes search functionality but does not include any warning that results may contain private user data in terminal output or downstream logs.

Content

No source excerpt is available for this finding.

Natural-Language Policy Violations

Low
Category
Not specified by scanner
Confidence
46% confidence
Finding

SQP-3 covers natural-language language or locale policy violations across all file types. The instruction to use the system default opener could implicitly enforce system-localized behavior, but the policy concern is weak because this is not an explicit language mandate.

Content

No source excerpt is available for this finding.

Static analysis

No suspicious patterns detected.