it's possible to use as-path-filter :)
as-path-filter
I have something similar for IP, not for AS.
ip prefix-list bogons index 10 deny 0.0.0.0 8 less-equal 32
ip prefix-list bogons index 20 deny 10.0.0.0 8 less-equal 32
ip prefix-list bogons index 30 deny 100.64.0.0 10 less-equal 32
ip prefix-list bogons index 40 deny 127.0.0.0 8 less-equal 32
ip prefix-list bogons index 50 deny 169.254.0.0 less-equal le 32
ip prefix-list bogons index 60 deny 172.16.0.0 12 less-equal 32
ip prefix-list bogons index 70 deny 192.0.0.0 24 less-equal 32
ip prefix-list bogons index 80 deny 192.0.2.0 24 less-equal 32
ip prefix-list bogons index 90 deny 192.168.0.0 16 less-equal 32
ip prefix-list bogons index 100 deny 198.18.0.0 15 less-equal 32
ip prefix-list bogons index 110 deny 198.51.100.0 24 less-equal 32
ip prefix-list bogons index 120 deny 203.0.113.0 24 less-equal 32
ip prefix-list bogons index 130 deny 224.0.0.0 3 less-equal 32
ip prefix-list bogons index 666 permit 0.0.0.0 0 less-equal 32
<Huawei> system-view
[Huawei] bgp 100
[Huawei-bgp] peer 10.1.1.2 as-number 200
[Huawei-bgp] ipv4-family unicast
[Huawei-bgp-af-ipv4] peer 10.1.1.2 ip-prefix bogons import