Chinese Ebook Downloader

• Outcome: Review
• Latest audit: May 29, 2026 at 9:28 PM UTC
• Version:
  2.0.0

Overview

The skill largely does what it claims, but it automates downloads from untrusted ebook/file-hosting sites, extracts remote archives, and can overwrite local files without strong user control.

Review before installing. Use only in a sandbox or dedicated empty output folder, assume book queries and download behavior are exposed to third-party sites, avoid opening downloaded files until scanned, and check copyright/source trust. VirusTotal was pending, so this verdict relies on artifact behavior rather than malware telemetry.

SkillSpector

By NVIDIA

Vulnerability Patterns

• Data Exfiltration: External Transmission, Env Variable Harvesting, File System Enumeration
• Excessive Agency: Unrestricted Tool Access, Autonomous Decision Making, Scope Creep
• Trigger Abuse: Overly Broad Trigger, Shadow Command Trigger, Keyword Baiting Trigger
• Behavioral AST: exec() Call, eval() Call, Dynamic Import
• MCP Least Privilege: Underdeclared Capability, Wildcard Permission, Missing Permission Declaration

Findings (12)

subprocess module call

Medium

• Category: Dangerous Code Execution

Content

# Try direct curl first
            cmd = ["curl", "-L", "-o", out_path, "--max-time", "300", url]
            result = subprocess.run(cmd, capture_output=True, text=True, timeout=310)
            if os.path.exists(out_path) and os.path.getsize(out_path) > 5000:
                return out_path

• Confidence: 88% confidence
• Finding: result = subprocess.run(cmd, capture_output=True, text=True, timeout=310)

subprocess module call

Medium

• Category: Dangerous Code Execution

Content

dl_url = await get_download_url(r['file_host_url'], pwd, headless=True)
            if dl_url:
                cmd = ["curl", "-L", "-o", out_path, "--max-time", "600", dl_url]
                subprocess.run(cmd, capture_output=True, text=True, timeout=610)
                if os.path.exists(out_path) and os.path.getsize(out_path) > 5000:
                    return out_path

• Confidence: 90% confidence
• Finding: subprocess.run(cmd, capture_output=True, text=True, timeout=610)

subprocess module call

Medium

• Category: Dangerous Code Execution

Content

extract_dir = f"/tmp/ebook_extract_{int(time.time())}"
                                os.makedirs(extract_dir, exist_ok=True)
                                try:
                                    subprocess.run(["unzip", "-o", "-d", extract_dir, f], capture_output=True, timeout=60)
                                    pdfs = glob.glob(os.path.join(extract_dir, "**/*.pdf"), recursive=True)
                                    for pdf in pdfs:
                                        if os.path.getsize(pdf) > 5000:

• Confidence: 86% confidence
• Finding: subprocess.run(["unzip", "-o", "-d", extract_dir, f], capture_output=True, timeout=60)

Lp3

Medium

• Category: MCP Least Privilege
• Confidence: 93% confidence
• Finding: The skill clearly instructs use of network access, shell commands, and local file writes/extraction, but it declares no permissions or safety boundaries. That mismatch is dangerous because an agent or user may invoke a capability-heavy workflow without explicit consent, review, or sandboxing, increasing the risk of arbitrary downloads, filesystem modification, and execution-adjacent abuse through fetched content.

Context-Inappropriate Capability

Medium

• Confidence: 88% confidence
• Finding: The code intentionally modifies browser fingerprints to evade bot detection by setting navigator.webdriver to undefined and spoofing chrome runtime. In the context of an ebook-downloader targeting shadow-library mirrors, this increases risk because it is designed to bypass access controls and makes automated retrieval from untrusted sites harder to audit and govern.

Vague Triggers

Medium

• Confidence: 91% confidence
• Finding: The README says the skill auto-triggers on very common ebook-request phrases, but does not describe consent gates, confirmation prompts, or boundaries on what sources may be contacted. In a skill that performs browser automation, downloads files, and extracts archives, broad trigger conditions can cause unintended network activity and retrieval of potentially risky content from third-party sites.

Missing User Warnings

Medium

• Confidence: 88% confidence
• Finding: The README promotes fully automated search, decryption, download, and ZIP extraction without warning users that the skill will perform network actions and process untrusted archives. That is dangerous because users may invoke it without understanding that it can fetch attacker-controlled files and unpack them locally, increasing the risk of harmful file writes or unsafe content handling.

Missing User Warnings

Medium

• Confidence: 90% confidence
• Finding: The troubleshooting section discusses browser automation, API extraction, and curl-based downloads to external file hosts, but provides no privacy or network disclosure. In context, this makes the skill more dangerous because users may not realize their queries, IP address, browser fingerprint, and download behavior are being exposed to multiple third-party services.

Missing User Warnings

Low

• Confidence: 87% confidence
• Finding: The skill tells the agent to download ebooks, save outputs, convert formats, and extract ZIP contents, but it does not warn that local files will be created or modified. This is risky because users may not realize the skill will write data to disk, potentially overwrite files, consume storage, or unpack malicious archives from untrusted sources.

Missing User Warnings

Medium

• Confidence: 91% confidence
• Finding: The script deletes any existing destination file with the same basename before moving the newly downloaded file into place, with no confirmation, backup, or integrity check. If a download yields an unexpected filename or a stale/corrupt file, legitimate local files in the output directory can be silently lost.

Missing User Warnings

Medium

• Confidence: 76% confidence
• Finding: The script reads an environment-sourced default password and then searches for that value in arbitrary page text from external sites. While it does not directly exfiltrate the secret, loading a potentially sensitive environment value into logic that processes untrusted remote content is risky and unnecessary, especially in an agent setting where environment variables may contain reused secrets.

Missing User Warnings

Medium

• Confidence: 93% confidence
• Finding: The skill automatically downloads remote files to a constructed output path without an explicit confirmation gate at the moment of download. In this context, the sources are untrusted mirror and partner sites, so silent download increases the chance of saving unexpected, malicious, or policy-violating content to disk.

VirusTotal

67/67 vendors flagged this skill as clean.