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Security audit

danish-grocery-deals

Security checks for vulnerabilities and agentic risk

Overview

This skill does what it claims: it fetches Danish grocery deals, writes local summaries, and optionally sends them to ntfy.sh notifications.

Before installing, use a random or authenticated ntfy topic, treat the config file as sensitive if you add a token, and review or clean the generated data directory if you do not want deal history retained locally.

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
  • Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
  • Privilege EscalationExcessive Permissions, Sudo/Root Execution, Credential Access
  • Trigger AbuseOverly Broad Trigger, Shadow Command Trigger, Keyword Baiting Trigger
  • Behavioral ASTexec() Call, eval() Call, Dynamic Import
  • MCP Least PrivilegeUnderdeclared Capability, Wildcard Permission, Missing Permission Declaration
Findings (12)

Tp4

High
Category
MCP Tool Poisoning
Confidence
94% confidence
Finding

The declared purpose understates the actual behavior by omitting local file creation/retention, stdout export, and credentialed local configuration handling. This mismatch can mislead users about where data is stored or exposed, which is risky when the skill processes API keys, notification topics, and generated deal files.

Content

No source excerpt is available for this finding.

Credential Access

High
Category
Privilege Escalation
Confidence
70% confidence
Finding

Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.

Content

Scanner excerpt · SKILL.md (reported line 96)May include surrounding context.

md
- Attachments (full deal list) must POST to `https://ntfy.sh/<topic>` with a
  `Filename:` header; posting to the root path fails with 413
- Public topics: use a random topic suffix, or set `ntfy.token` to a ntfy.sh
  access token and the script adds an Authorization header

## Troubleshooting
- `HTTP 400` on catalogs: you used `retailerId` instead of `dealer_id`

Undeclared Tool Scope

Medium
Category
MCP Least Privilege
Confidence
88% confidence
Finding

The skill advertises networked scraping, local config handling, and scheduled execution, but it does not declare any explicit tool scope or permissions boundary. In an agent environment, undeclared file, network, or shell capabilities increase the chance of over-privileged execution and make it harder for users to assess what the skill may access or modify.

Content

No source excerpt is available for this finding.

Missing User Warnings

Medium
Category
Not specified by scanner
Confidence
91% confidence
Finding

The skill sends summaries and attachments to ntfy.sh but does not prominently warn that topics are public by default unless protected. This can expose shopping interests, schedules, or attached deal lists to unintended parties if users choose predictable topic names or assume notifications are private.

Content

No source excerpt is available for this finding.

Natural-Language Policy Violations

Medium
Category
Not specified by scanner
Confidence
95% confidence
Finding

The module description and later user-facing strings indicate the skill is designed around Danish content ('tilbudsavis', 'Ugens tilbud', 'alle-tilbud'). The file does not offer any user opt-in or configurable locale, which matches the policy category for forcing a specific language without user choice.

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/notify.py (reported line 19)May include surrounding context.

python
def run_scraper() -> str:
    p = subprocess.run(
        ["python3", str(BASE / "tilbudsavis.py")],
        capture_output=True, text=True, timeout=900,
    )

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/notify.py (reported line 68)May include surrounding context.

python
if NTFY.get("token"):
                cmd.insert(-1, "-H")
                cmd.insert(-1, "Authorization: Bearer " + NTFY["token"])
            p = subprocess.run(cmd, capture_output=True, text=True, timeout=60)
            statuses.append(p.stdout.strip())
        finally:
            pathlib.Path(tmp).unlink(missing_ok=True)

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/notify.py (reported line 84)May include surrounding context.

python
if NTFY.get("token"):
        cmd.insert(-1, "-H")
        cmd.insert(-1, "Authorization: Bearer " + NTFY["token"])
    p = subprocess.run(cmd, capture_output=True, text=True, timeout=120)
    return p.stdout.strip()

Natural-Language Policy Violations

Medium
Category
Not specified by scanner
Confidence
95% confidence
Finding

The file is written to produce Danish-language summaries and uses a fixed Europe/Copenhagen locale context, with output strings such as 'Ugens bedste tilbud' and 'Ingen wow-tilbud denne uge'. This effectively forces a specific language/locale behavior without any user opt-in or explicit documentation that the skill is intentionally Denmark-specific.

Content

No source excerpt is available for this finding.

Missing User Warnings

Low
Category
Not specified by scanner
Confidence
80% confidence
Finding

This Python file reads an API key from config.json and uses it in authenticated HTTP requests to an external API. While the module docstring explains that it uses the Tjek API, there is no user-facing logging, prompt, or explicit warning near the network operation itself that the script performs authenticated network access and transmits request metadata externally.

Content

No source excerpt is available for this finding.

Natural-Language Policy Violations

Low
Category
Not specified by scanner
Confidence
92% confidence
Finding

The config includes Danish store URLs and Danish category/keyword terms such as "etilbudsavis.dk", "Oksekod", and "Kylling", which indicates the skill is constrained to a specific language/locale. Under the policy, locale-specific behavior should either offer user choice or be clearly documented and justified.

Content

No source excerpt is available for this finding.

Natural-Language Policy Violations

Low
Category
Not specified by scanner
Confidence
88% confidence
Finding

The natural-language description uses Danish ("tilbudsavis") and the schedule is hard-coded to the Europe/Copenhagen timezone, which together indicate a locale-specific behavior. In this file there is no user choice, opt-in, or documented justification that the skill is intentionally region-specific, so this may violate language/locale policy guidance.

Content

No source excerpt is available for this finding.

Static analysis

No suspicious patterns detected.