T05 · Unauthorized Access and Privilege Escalation
Warning
- Location
- image_reader.py:31
- Finding
- Unrestricted Local File Upload to an External API<![CDATA[ ## Vulnerability Details **File Location**: `image_reader.py:31-34`, `image_reader.py:51`, `image_reader.py:66`, `image_reader.py:74-80`, and `image_reader.py:98-103` **Vulnerability Type**: Unrestricted local file access and external transmission **Risk Level**: Medium ### Vulnerable Code ```python def encode_image(image_path: str) -> str: """将图片编码为 base64""" with open(image_path, "rb") as image_file: return base64.b64encode(image_file.read()).decode('utf-8') ``` ```python # 编码图片 base64_image = encode_image(image_path) ``` ```python { "type": "image_url", "image_url": { "url": f"data:image/png;base64,{base64_image}" } } ``` ```python response = client.chat.completions.create( model=model, messages=messages, temperature=0.7, max_tokens=64000 ) ``` ```python parser.add_argument('image_path', help='图片文件路径') parser.add_argument('--prompt', '-p', help='额外的分析提示', default=None) args = parser.parse_args() # 检查图片文件是否存在 if not os.path.exists(args.image_path): print(f"错误: 图片文件不存在: {args.image_path}") sys.exit(1) ``` ### Technical Analysis The program accepts an arbitrary filesystem path and checks only whether that path exists. It does not verify that the target is a regular file, that it is located in an approved directory, or that its content is a supported image format. The complete file is then read into memory, Base64-encoded, labeled as `image/png` regardless of its real type, and transmitted to the externally configured API endpoint. Base64 encoding is a legitimate and documented transport mechanism for multimodal API requests; it is not inherently a covert exfiltration technique. The security issue is the absence of controls around which local files may be encoded and uploaded. The process cannot read files beyond its operating-system permissions. Nevertheless, when invoked by an agent running with broader access than the requesting user, this behavior can cross a least-privilege bo ...[truncated 2033 chars]
- Remediation
- <![CDATA[ ## Remediation Suggestions 1. Resolve the supplied path with `Path.resolve()` and require it to remain inside an explicitly approved image-upload directory. 2. Require the target to be a regular file using `Path.is_file()` and reject symbolic links, device files, named pipes, sockets, and directories. 3. Validate the content using trusted image decoding or file-signature inspection rather than relying only on the filename extension. 4. Permit only explicitly supported image formats and derive the data URI MIME type from validated content rather than always using `image/png`. 5. Enforce a conservative maximum input size before reading the file. Read in a controlled manner rather than loading an unbounded file into memory. 6. In agent-driven use, require explicit user confirmation that identifies both the selected file and the external destination before uploading. 7. Run the Skill under a dedicated, least-privileged account with access only to approved image directories. 8. Clearly disclose the external endpoint and applicable data-retention policy at invocation time. 9. Prefer direct attachment objects or bounded streaming mechanisms if supported by the API client. ]]>