Here is an explanation of the shared code in literate markdown form:
This code handles uploading a file to the server. It exports an async function that takes in the request and response objects.
It first checks if the request method is GET, and returns an error if so, since this endpoint is only for uploading files.
It then uses the multiparty
package to parse the multipart form data from the request. This separates the fields and files from the request.
The promise returned by form.parse
resolves to an object containing the fields and files. The file data and file name are extracted from this.
The file data is then written to the user's home directory under .ssh
using the fs
module.
If the write is successful, a 200 success response is sent. Otherwise a 400 error is returned.
export default async function handler(req, res) {
// Check request method
if (req.method === 'GET') {
return res.status(400).json({ Error: 'Method not allowed.' });
}
// Use multiparty to parse form data
const form = new multiparty.Form();
const data = await new Promise((resolve, reject) => {
form.parse(req, function (err, fields, files) {
if (err) reject({ err });
resolve({ fields, files });
});
});
// Extract file data and file name
const fileData = data.fields.file[0];
const fileName = data.fields.fileName[0];
// Write file data to user's home dir
writeFile(`${home}/.ssh/${fileName}`, fileData, function (err, data) {
if (err) throw err;
return res.status(200).json({ body: 'Uploaded successfully' });
});
} catch (error) {
console.log(error);
return res.status(400).json('Failed');
}
-
The endpoint allows uploading files to the server without authentication. This could allow an attacker to overwrite important files. Proper authentication should be added.
-
The file is written to the user's home directory which could allow overwriting any files the process has access to. A dedicated upload folder should be used instead.
-
User input for the filename is used directly without sanitization. This could allow path traversal if the input contains relative paths like ../../etc/passwd. File names should be sanitized before use.
-
There is no size limit on uploads which could allow a denial of service attack. Max file sizes should be enforced.
-
Uploaded files are not scanned for malware. Virus scanning should be considered for security.
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Error handling is minimal. More robust error handling should be added to catch and log errors appropriately.