CVE-2024-31217

Strapi is an open-source content management system. Prior to version 4.22.0, a denial-of-service vulnerability is present in the media upload process causing the server to crash without restarting, affecting either development and production environments. Usually, errors in the application cause it to log the error and keep it running for other clients. This behavior, in contrast, stops the server execution, making it unavailable for any clients until it's manually restarted. Any user with access to the file upload functionality is able to exploit this vulnerability, affecting applications running in both development mode and production mode as well. Users should upgrade @strapi/plugin-upload to version 4.22.0 to receive a patch.

Strapi is an open-source content management system. Prior to version 4.22.0, a denial-of-service vulnerability is present in the media upload process causing the server to crash without restarting, affecting either development and production environments. Usually, errors in the application cause it to log the error and keep it running for other clients. This behavior, in contrast, stops the server execution, making it unavailable for any clients until it's manually restarted. Any user with access to the file upload functionality is able to exploit this vulnerability, affecting applications running in both development mode and production mode as well. Users should upgrade @strapi/plugin-upload to version 4.22.0 to receive a patch.

### Summary A Denial-of-Service was found in the media upload process causing the server to crash without restarting, affecting either development and production environments. ### Details Usually, errors in the application cause it to log the error and keep it running for other clients. This behavior, in contrast, stops the server execution, making it unavailable for any clients until it's manually restarted. ### PoC Due to a bug in what we believe to be Burp’s decoding system, we couldn’t produce a valid file to easily reproduce the vulnerability. Instead, the issue can be reproduced by following these steps: 1. Configure Burp’s proxy between a browser and a Strapi server 2. Log in and upload an image through the Media Library page while having Burp’s interceptor turned on 3. After capturing the upload POST request in Burp, add `%00` at the end of the file extension from the `Content-Disposition`, in the filename parameter (See reference image 1 below) 4. Using the cursor, select the added `%00` and right-click it. Click in Convert selection > URL > URL decode to transform the selected text into a null byte 5. Forward the modified request. The server should print an error and crash with the error `ERR_INVALID_ARG_VALUE` (See reference log 1 below) By following the data flow, we reached the [line of code](https://github.com/strapi/strapi/blob/f1dd5cc8eef574bac6679aab6f93276e57497328/packages/providers/upload-local/src/index.ts#L86) where we believe the DoS is being caused. The simpler way of fixing this vulnerability seems to be avoiding the error thrown by whitelisting the characters used in the extension. #### Reference Image 1  #### Reference Log 1 ``` [2024-03-22 10:23:42.629] http: POST /upload (22 ms) 400 node:internal/fs/utils:379 const err = new ERR_INVALID_ARG_VALUE( ^ TypeError [ERR_INVALID_ARG_VALUE]: The argument 'path' must be a string, Uint8Array, or URL without null bytes. Received '/mnt/storage/Development/GHSA-pm9q-xj9p-96pm/public/uploads/replaceme_png_88efe6a165.png\x00' at new WriteStream (node:internal/fs/streams:340:5) at Object.createWriteStream (node:fs:3123:10) at /mnt/storage/Development/GHSA-pm9q-xj9p-96pm/node_modules/@strapi/provider-upload-local/dist/index.js:71:33 at new Promise (<anonymous>) at Object.uploadStream (/mnt/storage/Development/GHSA-pm9q-xj9p-96pm/node_modules/@strapi/provider-upload-local/dist/index.js:68:16) at Object.uploadStream (/mnt/storage/Development/GHSA-pm9q-xj9p-96pm/node_modules/@strapi/plugin-upload/server/register.js:80:35) at Object.upload (/mnt/storage/Development/GHSA-pm9q-xj9p-96pm/node_modules/@strapi/plugin-upload/server/services/provider.js:16:46) at Object.uploadImage (/mnt/storage/Development/GHSA-pm9q-xj9p-96pm/node_modules/@strapi/plugin-upload/server/services/upload.js:220:48) { code: 'ERR_INVALID_ARG_VALUE' } ``` ### Impact Denial-of-Service occurs when a service becomes unavailable for users or other services. By sending a specially-crafted request, the server crashes without restarting. The entire server crashes with the thrown error instead of crashing only the single request and returning error 500 to the user. Any user with access to the file upload functionality is able to exploit this vulnerability, affecting applications running in both development mode and production mode as well.

### Summary A Denial-of-Service was found in the media upload process causing the server to crash without restarting, affecting either development and production environments. ### Details Usually, errors in the application cause it to log the error and keep it running for other clients. This behavior, in contrast, stops the server execution, making it unavailable for any clients until it's manually restarted. ### PoC Due to a bug in what we believe to be Burp’s decoding system, we couldn’t produce a valid file to easily reproduce the vulnerability. Instead, the issue can be reproduced by following these steps: 1. Configure Burp’s proxy between a browser and a Strapi server 2. Log in and upload an image through the Media Library page while having Burp’s interceptor turned on 3. After capturing the upload POST request in Burp, add `%00` at the end of the file extension from the `Content-Disposition`, in the filename parameter (See reference image 1 below) 4. Using the cursor, select the added `%00` and right-click it. Click in Convert selection > URL > URL decode to transform the selected text into a null byte 5. Forward the modified request. The server should print an error and crash with the error `ERR_INVALID_ARG_VALUE` (See reference log 1 below) By following the data flow, we reached the [line of code](https://github.com/strapi/strapi/blob/f1dd5cc8eef574bac6679aab6f93276e57497328/packages/providers/upload-local/src/index.ts#L86) where we believe the DoS is being caused. The simpler way of fixing this vulnerability seems to be avoiding the error thrown by whitelisting the characters used in the extension. #### Reference Image 1  #### Reference Log 1 ``` [2024-03-22 10:23:42.629] http: POST /upload (22 ms) 400 node:internal/fs/utils:379 const err = new ERR_INVALID_ARG_VALUE( ^ TypeError [ERR_INVALID_ARG_VALUE]: The argument 'path' must be a string, Uint8Array, or URL without null bytes. Received '/mnt/storage/Development/GHSA-pm9q-xj9p-96pm/public/uploads/replaceme_png_88efe6a165.png\x00' at new WriteStream (node:internal/fs/streams:340:5) at Object.createWriteStream (node:fs:3123:10) at /mnt/storage/Development/GHSA-pm9q-xj9p-96pm/node_modules/@strapi/provider-upload-local/dist/index.js:71:33 at new Promise (<anonymous>) at Object.uploadStream (/mnt/storage/Development/GHSA-pm9q-xj9p-96pm/node_modules/@strapi/provider-upload-local/dist/index.js:68:16) at Object.uploadStream (/mnt/storage/Development/GHSA-pm9q-xj9p-96pm/node_modules/@strapi/plugin-upload/server/register.js:80:35) at Object.upload (/mnt/storage/Development/GHSA-pm9q-xj9p-96pm/node_modules/@strapi/plugin-upload/server/services/provider.js:16:46) at Object.uploadImage (/mnt/storage/Development/GHSA-pm9q-xj9p-96pm/node_modules/@strapi/plugin-upload/server/services/upload.js:220:48) { code: 'ERR_INVALID_ARG_VALUE' } ``` ### Impact Denial-of-Service occurs when a service becomes unavailable for users or other services. By sending a specially-crafted request, the server crashes without restarting. The entire server crashes with the thrown error instead of crashing only the single request and returning error 500 to the user. Any user with access to the file upload functionality is able to exploit this vulnerability, affecting applications running in both development mode and production mode as well.

Strapi es un sistema de gestión de contenidos de código abierto. Antes de la versión 4.22.0, había una vulnerabilidad de denegación de servicio en el proceso de carga de medios que provocaba que el servidor fallara sin reiniciarse, lo que afectaba los entornos de desarrollo y producción. Por lo general, los errores en la aplicación hacen que registre el error y lo mantenga ejecutándose para otros clientes. Este comportamiento, por el contrario, detiene la ejecución del servidor, haciéndolo no disponible para ningún cliente hasta que se reinicie manualmente. Cualquier usuario con acceso a la función de carga de archivos puede aprovechar esta vulnerabilidad, lo que afecta también a las aplicaciones que se ejecutan tanto en modo de desarrollo como en modo de producción. Los usuarios deben actualizar @strapi/plugin-upload a la versión 4.22.0 para recibir un parche.