Wi-Fi network not showing its security in "iw wlan0 scan"

Question

A network with a key is showing up this way when running iw wlan0 scan on an OpenWRT device:

BSS 00:26:50:41:c7:01(on wlan0)
  TSF: 20161559489 usec (0d, 05:36:01)
  freq: 2462
  beacon interval: 100 TUs
  capability: ESS (0x0431)
  signal: -25.00 dBm
  last seen: 30 ms ago
  Information elements from Probe Response frame:
  SSID: BELL405

I'm debugging this remotely with a non-technical user and don't know exactly what form of security is present, only that the network has a key that is used when connecting other devices. I might have written this off as user confusion if this wasn't the second case of a user swearing their network needs a key but the scan looking similar.

Am I missing something here I could use to detect that a key is required? I've seen RSN, WPA or Privacy on every other network with a key.

Answer 1

After running into this several more times, all with Bell (a Canadian ISP) routers, I figured out by trial and error that these routers have WEP security enabled even though they're not reporting it. Given the lack of HT Capabilities section, I'm guessing they're 802.11b/g and so quite old.