4 symbols WPA2 password?

[meshkoff]

Hi all

Recently i captured WPA2 handshake that contains only 4 symbol password length:

Code:

BSSID=70:9f:2d:b5:be:c0 ESSID=oso3 (Length: 4)\
--> STA=fc:f1:36:c9:34:ee, Message Pair=0, Replay Counter=10\
--> STA=fc:f1:36:c9:34:ee, Message Pair=2, Replay Counter=10}

When i tried brute-force it with hashcat it says:

Code:

Skipping mask '?d?d?d?d' because it is smaller than the minimum password length

1) How can it be, if WPA2 minimum password length is 8 symbols? Is it wrong capture? 
I doublechecked with WiFi Explorer that target SSID has WPA2 protection

2) How can i bypass minimum password length limit?