Vodafone Station Exporter

Prometheus Exporter for the Vodafone Station (CGA4233DE)

Exposes various information such as DOCSIS channel status.

Usage

Usage of ./vodafone-station-exporter:
  -version
    	Print version and exit
  -vodafone.station-password string
    	Password for logging into the Vodafone station (default "How is the default password calculated? mhmm")
  -vodafone.station-url string
    	Vodafone station URL. For bridge mode this is 192.168.100.1 (note: Configure a route if using bridge mode) (default "http://192.168.0.1")
  -web.listen-address string
    	Address to listen on (default "[::]:9420")
  -web.telemetry-path string
    	Path under which to expose metrics (default "/metrics")

Reverse Engineering the login mechanism

I am not a Javascript engineer, but it works 🤷‍♂️

Logging into the PHP application running on the CGA4233DE is made as complicated as possible.

From the console we see:

curl 'http://192.168.100.1/api/v1/session/login' \
  -H 'Connection: keep-alive' \
  -H 'Accept: */*' \
  -H 'X-CSRF-TOKEN: ' \
  -H 'X-Requested-With: XMLHttpRequest' \
  -H 'Content-Type: application/x-www-form-urlencoded; charset=UTF-8' \
  --data-raw 'username=admin&password=seeksalthash' \
  --compressed \
  --insecure

CSRF seems broken, lol. Whatever - we don't care.

reply is

{"error":"ok","salt":"<something>","saltwebui":"<something_else>"}

For the actual login a derived token derived from the actual password is used:

curl 'http://192.168.100.1/api/v1/session/login' \
  -H 'Connection: keep-alive' \
  -H 'Accept: */*' \
  -H 'X-CSRF-TOKEN: ' \
  -H 'X-Requested-With: XMLHttpRequest' \
  -H 'Content-Type: application/x-www-form-urlencoded; charset=UTF-8' \
  -H 'Cookie: <some PHP session cookie>' \
  --data-raw 'username=admin&password=<something that is not my password>' \
  --compressed \
  --insecure

Looking at the obfuscated JavaShit (login.js), we see something like follows:

doPbkdf2NotCoded(doPbkdf2NotCoded("<password>", "<salt>"), "<saltwebui>")

quick check reveals: Yes, that returns the token used for the login. ✔️

Ok, so what does doPbkdf2NotCoded do?

function doPbkdf2NotCoded(_0x365ad6, _0x470596) {
    var _0x51b261 = sjcl[_0x5bfa('0x10')][_0x5bfa('0x11')](_0x365ad6, _0x470596, 0x3e8, 0x80);
    var _0x279f24 = sjcl[_0x5bfa('0xc')][_0x5bfa('0x12')]['fromBits'](_0x51b261);
    return _0x279f24;
}

easy, isn't it? %) Turns out, sjcl is not yet another obfuscated JS function, but this thingie.

Translated to something slightly more human readable (using the JS console)

function whatTheFuck(param1, param2) {
    //                                a,      b,      c,     d
    var temp = sjcl["misc"]["pbkdf2"](param1, param2, 0x3e8, 0x80)
    return sjcl["codec"]["hex"]["fromBits"](temp)
}

From here, I started the GoLang implementation, which looks as follows:

// GetLoginPassword derives the password using the given salts
func GetLoginPassword(password, salt, saltWebUI string) string {
    return DoPbkdf2NotCoded(DoPbkdf2NotCoded(password, salt), saltWebUI)
}

// Equivalent to the JS doPbkdf2NotCoded (see README.md) 
func DoPbkdf2NotCoded(key, salt string) string {
    temp := pbkdf2.Key([]byte(key), []byte(salt), 0x3e8, 0x80, sha256.New)
    return hex.EncodeToString(temp[:16])
}