Summary
When passing a non-existing folder to the actix_files::Files::new() method causes the actix server to expose unexpected files.
Details
The actix-files library exposes a Files struct that configures an actix service to serve the files in a folder as static assets. Below you can find the signature of the Files::new method:
pub fn new<T: Into<PathBuf>>(mount_path: &str, serve_from: T) -> Files
When the mount_path you pass to Files doesn't exist, it defaults to an empty path (Path::new()). When the service receives a HTTP request, it joins the request information with the empty path and calls canonicalize. Rust resolves this path as relative and returns any file that matches it.
This behavior causes the library to expose unexpected files when the folder is not present.
PoC
There is a working PoC on https://github.com/Angelmmiguel/actix-files-vuln, although the next steps can be followed to reproduce the issue
-
Clone the https://github.com/actix/examples repository.
-
Change your directory to the basics/static-files folder.
-
Edit the src/main.rs file and change the line 13 to mount a non-existing folder:
- .service(Files::new("/images", "static/images/").show_files_listing())
+ .service(Files::new("/images", "static/missing/").show_files_listing())
-
Run the project with cargo run.
-
Access the http://localhost:8080/images/Cargo.toml URL.
Impact
This is an exposure of information vulnerability. It affects anyone using the actix-files::Files library that mounts a non-existing folder for any reason.
References
Summary
When passing a non-existing folder to the
actix_files::Files::new()method causes the actix server to expose unexpected files.Details
The
actix-fileslibrary exposes aFilesstruct that configures an actixserviceto serve the files in a folder as static assets. Below you can find the signature of theFiles::newmethod:When the
mount_pathyou pass toFilesdoesn't exist, it defaults to an empty path (Path::new()). When the service receives a HTTP request, it joins the request information with the empty path and callscanonicalize. Rust resolves this path as relative and returns any file that matches it.This behavior causes the library to expose unexpected files when the folder is not present.
PoC
There is a working PoC on https://github.com/Angelmmiguel/actix-files-vuln, although the next steps can be followed to reproduce the issue
Clone the https://github.com/actix/examples repository.
Change your directory to the
basics/static-filesfolder.Edit the
src/main.rsfile and change the line 13 to mount a non-existing folder:Run the project with
cargo run.Access the http://localhost:8080/images/Cargo.toml URL.
Impact
This is an exposure of information vulnerability. It affects anyone using the
actix-files::Fileslibrary that mounts a non-existing folder for any reason.References