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Security audit

Gumroad Analytics

Security checks for vulnerabilities and agentic risk

Overview

This Gumroad analytics skill is mostly purpose-aligned, but it handles access tokens and sales data in ways that can expose sensitive information locally.

Review this before installing if you handle real Gumroad customer data. The skill appears aimed at legitimate analytics and does not show malicious exfiltration, but it should be hardened to avoid putting tokens or API payloads in command-line arguments, set restrictive permissions on output directories/files, and use an allowlist for any raw diagnostic exports.

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/fetch_metrics.sh:34
Finding

Access Token and Customer Data Exposed Through Process Arguments

Content
View full analysis
Remediation
View remediation

T09 · Insecure Skill Coding Practices

Warning
Location
scripts/fetch_metrics.sh:68
Finding

Optional Raw Sales Storage Uses Incomplete Redaction and Non-Explicit File Permissions

Content
View full analysis
"$PRODUCTS_RAW_PATH" echo "Raw files written (redacted sales):" echo "- $SALES_RAW_PATH" echo "- $PRODUCTS_RAW_PATH" fi ``` The output directory is created earlier without an explicit restrictive mode: ```bash OUT_DIR="memory/metrics/gumroad" mkdir -p "$OUT_DIR" ``` ### Technical Analysis The redaction logic removes only four top-level keys from each sales object: - `email` - `full_name` - `name` - `buyer_email` All other top-level fields, nested objects, arrays, custom fields, identifiers, and customer-supplied values remain unchanged. This denylist approach cannot guarantee that the resulting file is free of personally identifiable or sensitive information, particularly if the Gumroad response schema changes or contains relevant data under other field names. The product response receives no redaction at all. Although product data may be less sensitive than sales data, the complete response is written to disk. The files and directory are created without explicit restrictive permissions. Their effective permissions depend on the invoking user's current `umask`. Under a permissive `umask`, another local user may be able to read the stored payloads. The summary output is subject to the sa ...[truncated 1746 chars]
Remediation
View remediation

SkillSpector

Vulnerability Patterns
  • Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
  • Privilege EscalationExcessive Permissions, Sudo/Root Execution, Credential Access
  • MCP Least PrivilegeUnderdeclared Capability, Wildcard Permission, Missing Permission Declaration
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
  • Supply ChainUnpinned Dependencies, External Script Fetching, Obfuscated Code
Findings (8)

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 9)May include surrounding context.

md
STORE_RAW=1
fi

CRED_FILE="${GUMROAD_CREDENTIALS_FILE:-$HOME/.config/gumroad/credentials.json}"
if [[ ! -f "$CRED_FILE" ]]; then
  echo "Credentials file not found: $CRED_FILE" >&2
  exit 1

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 24)May include surrounding context.

md
STORE_RAW=1
fi

CRED_FILE="${GUMROAD_CREDENTIALS_FILE:-$HOME/.config/gumroad/credentials.json}"
if [[ ! -f "$CRED_FILE" ]]; then
  echo "Credentials file not found: $CRED_FILE" >&2
  exit 1

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 37)May include surrounding context.

md
STORE_RAW=1
fi

CRED_FILE="${GUMROAD_CREDENTIALS_FILE:-$HOME/.config/gumroad/credentials.json}"
if [[ ! -f "$CRED_FILE" ]]; then
  echo "Credentials file not found: $CRED_FILE" >&2
  exit 1

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 · scripts/fetch_metrics.sh (reported line 9)May include surrounding context.

sh
STORE_RAW=1
fi

CRED_FILE="${GUMROAD_CREDENTIALS_FILE:-$HOME/.config/gumroad/credentials.json}"
if [[ ! -f "$CRED_FILE" ]]; then
  echo "Credentials file not found: $CRED_FILE" >&2
  exit 1

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 · scripts/fetch_metrics.sh (reported line 25)May include surrounding context.

sh
)"

if [[ -z "$TOKEN" ]]; then
  echo "No access token found in $CRED_FILE (expected access_token or token)" >&2
  exit 1
fi

Undeclared Tool Scope

Medium
Category
MCP Least Privilege
Confidence
80% confidence
Finding

The skill declares shell, file read, and file write capabilities but does not scope or constrain them with an explicit permissions or allowed-tools policy. In an agent environment, this increases the attack surface because the agent may execute broader file or shell operations than necessary, including access to credential files and persistence into memory paths.

Content

No source excerpt is available for this finding.

Sudo/Root Execution

Medium
Category
Privilege Escalation
Confidence
80% confidence
Finding

Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.

Content

Scanner excerpt · SKILL.md (reported line 37)May include surrounding context.

Harden permissions:

bash
chmod 600 ~/.config/gumroad/credentials.json

Run

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 · scripts/fetch_metrics.sh (reported line 29)May include surrounding context.

sh
exit 1
fi

API="https://api.gumroad.com/v2"
TODAY="$(date +%F)"
OUT_DIR="memory/metrics/gumroad"
mkdir -p "$OUT_DIR"

Static analysis

No suspicious patterns detected.