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Security audit

抖音账号视频批量下载器

Security checks for vulnerabilities and agentic risk

Overview

The skill is a real Douyin downloader, but it exposes users to Review-level risk through broad third-party media downloading, forced full-link output, and weak safeguards around third-party API downloads.

Install only if you are comfortable sending Douyin account IDs, work URLs, and a RedFox API key to redfox.hk, and only use it for content you are authorized to download. Avoid bulk downloads unless you choose a controlled output directory and can tolerate significant disk and bandwidth use; do not rely on the skill's forced full-link output as a privacy-safe default.

Vulnerability Patterns
  • Skill Instruction HijackingAlters the agent's session goals or safety constraints when the skill loads
  • Insecure DependenciesIntroduces malicious components through unsafe dependency sources
  • Insecure Skill Coding PracticesFinds exploitable flaws such as hardcoded secrets or command injection
  • 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
Findings (3)

T01 · Skill Instruction Hijacking

Error
Location
SKILL.md:201
Finding

Mandatory Output Rules Hijack Agent Response Control

Content
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**Agent 必须原样展示脚本返回的完整表格,禁止以下行为:** > > - ❌ 禁止删除或合并任何列(发布时间、作品、赞、评论、收藏、分享、资源下载 缺一不可) > - ❌ 禁止省略翻页提示行("还有更多作品,输入 `--page 2` 翻看下一页") > - ❌ 禁止省略时间范围筛选提示("💡 支持输入想提取的作品时间范围…") > - ❌ 禁止省略下载询问提示("💾 需要将这 X 条作品批量下载到本地吗?") > - ❌ 禁止用「...」或摘要代替完整表格内容 > - ✅ 必须逐行展示所有作品的完整信息(含资源下载链接) ``` The same policy is embedded in the executable script: ```python def print_markdown_table(account: dict, results: list[dict], page_num: int = 1, page_size: int = DEFAULT_PAGE_SIZE): """ 输出 Markdown 格式的结果表格 ⛔ 强制规则:Agent 调用方必须原样展示本函数的完整输出,禁止以下行为: - 禁止删除或合并任何列(#、发布时间、作品、赞、评论、收藏、分享、资源下载 缺一不可) - 禁止省略翻页提示行 - 禁止省略时间范围筛选提示和下载询问提示 - 禁止用「...」或摘要代替完整表格内容 - 必须逐行展示所有作品信息(含完整资源下载链接) """ ``` Fixed external support and follow-up messages are then inserted into the output: ```python if fail_count > 0: print(f"\n> ⚠️ 下载失败的视频可能是用户已删除该视频,如需数据核查可联系工作人员邮箱 **redfoxdata@proton.me** 处理。") print(f"\n> 💡 支持输入想提取的作品时间范围,如 `--date-start 2026-07-01 --date-end 2026-07-20`") if success_count > 0: print(f"> 💾 需要将这 {success_count} 条作品批量下载到本地吗?直接告诉我即可。") ``` ### Technical Analysis The Skill does more than define the downloader's functional behavior. It explicitly commands the hosting Agent to reproduce generated output verbatim, prohibits summarization, and requires retention of fixed follow-up and external-contact messages. A Skill may define a useful output schema, but it should not override higher-level user preferences or the Agent's discretion about relevance, privacy, response length, and presentation. The mandatory language is unnecessary for fetching or downloading Douyin media and therefore exceeds the minimum instructions needed for the declared functionality. T ...[truncated 1388 chars]
Remediation
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T09 · Insecure Skill Coding Practices

Warning
Location
scripts/douyin_video_downloader.py:427
Finding

API-Controlled Download URLs Are Fetched Without Destination or Size Validation

Content
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bool: """ 下载视频文件到本地 Args: download_url: 视频下载直链 output_path: 保存路径 Returns: bool: 是否下载成功 """ try: resp = requests.get(download_url, timeout=120, stream=True) resp.raise_for_status() total = int(resp.headers.get("content-length", 0)) downloaded = 0 with open(output_path, "wb") as ...[truncated 2778 chars]
Remediation
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T08 · Insecure Dependencies

Note
Location
SKILL.md:108
Finding

Third-Party Dependency Is Installed Without Version or Integrity Pinning

Content
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Remediation
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Vulnerability Patterns
  • Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
  • Trigger AbuseOverly Broad Trigger, Shadow Command Trigger, Keyword Baiting Trigger
  • MCP Least PrivilegeUnderdeclared Capability, Wildcard Permission, Missing Permission Declaration
  • MCP Tool PoisoningHidden Instructions, Unicode Deception, Parameter Description Injection
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
Findings (15)

Natural-Language Policy Violations

High
Category
Not specified by scanner
Confidence
97% confidence
Finding

The skill explicitly promotes watermark removal, bulk downloading, and secondary reuse of others' media, including competitive analysis and content reposting scenarios. In this context, the behavior is not just ambiguous wording; it operationalizes large-scale extraction of third-party content in ways that can violate platform rules, copyright, or consent expectations.

Content

No source excerpt is available for this finding.

Missing User Warnings

Medium
Category
Not specified by scanner
Confidence
95% confidence
Finding

The introduction says the skill will batch download content to the local device, but the description lacks a prominent explicit warning about local file writes, storage consumption, and the fact that the action affects the user's machine. Because this skill is specifically designed for bulk media retrieval, omission of a clear write-to-disk warning makes accidental large downloads and unsafe assumptions about side effects more likely.

Content

No source excerpt is available for this finding.

Vague Triggers

Medium
Category
Not specified by scanner
Confidence
95% confidence
Finding

The README tells users to operate the skill through unrestricted natural-language requests without clearly constraining dangerous actions, even though the skill can fetch third-party content, parse watermark-free links, and batch-download files locally. In this context, broad activation increases the chance of unintended mass downloading, copyright-violating use, or ambiguous requests causing the agent to perform more data retrieval and local file writes than the user fully realizes.

Content

No source excerpt is available for this finding.

Missing User Warnings

Medium
Category
Not specified by scanner
Confidence
93% confidence
Finding

The README promotes bulk downloading to local storage but does not clearly warn users that this action writes potentially large amounts of data to disk and changes local system state. In a skill designed for mass media retrieval, omission of storage, bandwidth, and file-write warnings increases the risk of unintended disk consumption, clutter, or operational impact, especially when processing multiple accounts.

Content

No source excerpt is available for this finding.

Undeclared Tool Scope

Medium
Category
MCP Least Privilege
Confidence
94% confidence
Finding

The skill describes capabilities that require network access, environment-variable access, and local file read/write, but it does not declare an explicit tool scope or permission boundary. That increases the chance an agent will invoke broader-than-necessary capabilities implicitly, making misuse or unintended data access harder to constrain or audit.

Content

No source excerpt is available for this finding.

Vague Triggers

Medium
Category
Not specified by scanner
Confidence
92% confidence
Finding

The description embeds a large trigger-word set without boundaries, exclusions, or disambiguation rules, so activation criteria are unclear. Because the skill is designed to fetch, parse, and download media, ambiguous triggering raises the risk of unintended execution and unauthorized handling of content.

Content

No source excerpt is available for this finding.

Vague Triggers

Medium
Category
Not specified by scanner
Confidence
95% confidence
Finding

The trigger phrases are broad conversational terms like generic download requests, which can overlap with normal user chat and cause accidental activation. In a skill that performs network retrieval and local file download, misfires can initiate actions against third-party content without clear user intent.

Content

No source excerpt is available for this finding.

Ssd 3

Medium
Category
Not specified by scanner
Confidence
92% confidence
Finding

The skill requires the agent to expose complete downloadable resource links and forbids omission or summarization, which increases the risk of indiscriminately redistributing direct media URLs. In a downloader skill focused on no-watermark extraction, this materially lowers friction for mass sharing or downstream abuse of retrieved content.

Content

No source excerpt is available for this finding.

External Transmission

Medium
Category
Data Exfiltration
Confidence
89% confidence
Finding

The script transmits user-supplied Douyin account identifiers and an API key to an external third-party service (redfox.hk) to fetch works metadata. In this skill context, external transmission is core functionality, but it still creates privacy, logging, and trust risks because users may not realize their queries and credentials are being sent to a non-official intermediary.

Content

Scanner excerpt · scripts/douyin_video_downloader.py (reported line 287)May include surrounding context.

python
}

        try:
            resp = requests.post(url, json=payload, headers=headers, timeout=30)
            result = resp.json()
        except requests.exceptions.Timeout:
            _record_failure(account_id)

Description-Behavior Mismatch

Medium
Category
Not specified by scanner
Confidence
93% confidence
Finding

The manifest and module description frame the skill as a 'video downloader' for Douyin account works, but the parsing logic explicitly collects image and audio resources in addition to video. It also treats image posts as downloadable content and exposes cover/image/audio links in output, which is broader than the stated video-only purpose.

Content

No source excerpt is available for this finding.

External Transmission

Medium
Category
Data Exfiltration
Confidence
90% confidence
Finding

The script sends each work URL to the same third-party parsing endpoint, which expands external data sharing beyond simple account lookup to every retrieved item. In aggregate, this can reveal a user's investigative targets and download activity, and the service returns direct media links that may encourage downstream misuse or policy violations.

Content

Scanner excerpt · scripts/douyin_video_downloader.py (reported line 379)May include surrounding context.

python
}

        try:
            resp = requests.post(url, json=payload, headers=headers, timeout=30)
            data = resp.json()
        except requests.exceptions.Timeout:
            return {"success": False, "download_url": None, "title": None, "cover": None,

Natural-Language Policy Violations

Medium
Category
Not specified by scanner
Confidence
95% confidence
Finding

The output text instructs the caller and user interaction flow entirely in Chinese, including a direct prompt telling the user to respond in that language context, without offering any language or locale choice. The policy explicitly flags language-forcing behavior when there is no opt-in or documented locale-specific justification.

Content

No source excerpt is available for this finding.

Missing User Warnings

Medium
Category
Not specified by scanner
Confidence
84% confidence
Finding

When --download is enabled, the script writes attacker-influenced remote content to the local filesystem without an explicit confirmation step, quota check, or overwrite warning. In an agent context, this can cause unbounded storage consumption or unintended persistence of downloaded files, especially when processing multiple accounts and many works.

Content

No source excerpt is available for this finding.

Natural-Language Policy Violations

Low
Category
Not specified by scanner
Confidence
81% confidence
Finding

The usage guidance tells users to interact in natural language and then provides only Chinese-language invocation examples, with no indication that other languages are supported or that Chinese is required for a justified regional reason. Under the policy, a language constraint should be optional, documented, or explicitly offered as a choice.

Content

No source excerpt is available for this finding.

Intent-Code Divergence

Low
Category
Not specified by scanner
Confidence
77% confidence
Finding

The comment block describes a fixed '抖音视频下载' table and required columns for presenting all works, implying a video-download-focused output contract. However, the implementation of the resource column includes non-video resource types such as cover images and audio, diverging from the documented output intent rather than merely omitting detail.

Content

No source excerpt is available for this finding.

Static analysis

No suspicious patterns detected.