smugchunks - A black-box scanner for HTTP request smuggling vul

项目说明

smugchunks

smugchunks is a black-box scanner for HTTP request smuggling caused by chunk parser differentials. Using timeout-based probes, it detects exploitable inconsistencies between front-end and back-end interpretations of chunked-coding HTTP requests.

This tool is in no way an alternative to the amazing Smuggler by defparam, and the two tools perform no o checks. Rather, it is intended to be its complement; whereas Smuggler identifies inconsistencies in the interpretation of the Content-Length and Transfer-Encoding headers, smugchunks identifies inconsistencies in the interpretation of the chunked message body itself.

For an introduction to the techniques that this tool is based on, see the accompanying blog post here.

Installation and usage

To get started, simply clone this repository, install the dependencies, and run the Python script.

You must supply either a single URL through the --url parameter or a list of URLs through the --input-file parameter. See python3 smugchunks.py --help for more command-line options.

smugchunks only *identifies* - it is not an exploitation tool. That part is up to you. If you're not sure how to exploit these kinds of request smuggling , take a look at Ben Kallus's and Prashant Anantharaman's ShmooCon talk or my own blog post.

Request smuggling techniques

Currently, smugchunks performs checks for the following :

__TERM.EXT and EXT.TERM__: Discrepancies in the parsing of line terminators in chunk extensions.

__TERM.SPILL and SPILL.TERM__: Discrepancies in the parsing of line terminators in o chunks.

__TERM.TRAIL__: Discrepancies in the parsing of line terminators in chunked trailer sections.

__Length-based (chunk body)__: Discrepancies in the percei of line terminators in chunk bodies.

I would like to add a test for TRAIL.TERM, as well as tests pertaining to discrepancies in the integer parsing of chunk sizes, but I haven't been able to figure out how to detect such blindly. If you know of a reliable way to identify such , feel free to reach out or open a PR.

A note on false positives

I'd love to tell you that smugchunks doesn't produce false positives. Unfortunately, that would be a lie. I've gone to great lengths to eliminate them, and in my experience they're really quite rare. Still, it does happen, and you should therefore always manually each finding from this tool before taking action; don't report scan results to bug bounty programs.

On a side note, if smugchunks consistently reports an issue that turns out to be a false positive, it probably means the front-end is doing some questionable HTTP parsing. Even if it's not exploitable in the way smugchunks expects, that parsing behavior could still be dangerous - definitely something worth digging into.

Acknowledgements

The timeout-based detection techniques that power smugchunks have been adapted from those introduced by James Kettle in 2019.

The request smuggling techniques supported by smugchunks are in part based on work by Matthias Grenfeldt, Asta Olofsson, Ben Kallus and Prashant Anantharaman.

项目信息

开发语言：Python

Star 数：35

技术要点

该项目属于安全软件方向的开源资源，代码结构清晰，适合安全研究人员学习参考。项目围绕A black-box scanner for HTTP request smuggling vulnerabilities caused by chunk parsing discrepancies.展开，提供了可运行的实现，对理解相关安全机制、工具原理与攻防技术具有较高的研究价值。

从技术实现角度看，此类项目的核心在于对底层原理的深入理解与工程化落地。开发者在研究过程中可以结合官方文档与社区讨论，梳理项目的初始化流程、核心模块职责与数据流转，逐步掌握其中的技术细节与设计思路。

使用与学习建议

1. 下载源码压缩包，解压到本地环境。

2. 根据项目类型准备对应的运行环境与依赖。

3. 按照 README 中的步骤完成配置与部署。

4. 在隔离的测试环境中运行验证，避免影响生产系统。

免责声明

本资源来源于开源社区，仅供安全研究、技术学习与合法授权范围内的攻防演练使用，请勿用于任何非法或侵害他人权益的用途。使用本项目产生的一切后果由使用者自行承担。