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377 lines (340 loc) · 16.2 KB
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-- wiremax — Wireshark dissector for Ubiquiti AirMAX (AC + M) and the
-- companion Mikrotik / RouterBoard vendor Information Elements.
--
-- AirMAX rides inside 802.11 vendor-specific IEs (tag 221). Rather than
-- replace Wireshark's built-in 802.11 dissector, this runs as a POSTDISSECTOR:
-- after the wlan dissector has split out the IEs, we read the per-IE OUIs and
-- the frame's source/dest MACs via Field extractors, locate each AirMAX IE in
-- the frame, AES-decrypt the payload (key = HMAC-SHA1(dst,src)[:16]; broadcast
-- dst fallback like pyrmax), and add a parsed subtree.
--
-- The decode logic mirrors the pyrmax Python package field-for-field; the
-- crypto is self-contained pure Lua (Wireshark exposes no crypto API to Lua).
--
-- Install: copy this file plus the wsairmax/ directory into a Wireshark
-- "Personal Lua Plugins" folder (Help > About Wireshark > Folders), or run
-- tshark -X lua_script:airmax.lua -r capture.pcap
-- Filters: airmax.ac.*, airmax.m.*, airmax.rb.* (e.g. airmax.ac.ssid).
-- Make wsairmax.* requireable from wherever Wireshark loads this file.
local here = debug.getinfo(1, "S").source:sub(2):match("^(.*[/\\])") or "./"
package.path = here .. "?.lua;" .. package.path
local util = require("wsairmax.util")
local crypto = require("wsairmax.crypto")
local ac = require("wsairmax.ac")
local m = require("wsairmax.m")
local rb = require("wsairmax.routerboard")
local OUI_AC = 0x002722
local OUI_M = 0x00156d
local OUI_RB = 0x000c42
local p_airmax = Proto("airmax", "Ubiquiti AirMAX")
-- ---------------------------------------------------------------------------
-- ProtoFields
-- ---------------------------------------------------------------------------
local AC_MSG_VS = ac.MSG_TYPE
local TLV_TAG_VS = ac.TLV_TAG
local M_MSG_VS = m.MSG_TYPE
local f = {
-- AC outer (cleartext)
ac_oui = ProtoField.bytes("airmax.ac.oui", "OUI"),
ac_oui_type = ProtoField.bytes("airmax.ac.oui_type", "OUI Type"),
ac_flags = ProtoField.uint8("airmax.ac.flags", "Flags", base.HEX),
ac_flag_enc = ProtoField.bool("airmax.ac.flags.encrypted", "Encrypted", 8, nil, 0x02),
ac_msg_type = ProtoField.uint8("airmax.ac.msg_type", "Message Type", base.DEC, AC_MSG_VS),
ac_enc_len = ProtoField.uint16("airmax.ac.enc_len", "Encrypted Length"),
ac_ct = ProtoField.bytes("airmax.ac.ciphertext", "Ciphertext"),
-- AC payload (decrypted): shared head
ac_key = ProtoField.string("airmax.ac.key", "AES Key (HMAC-SHA1(dst,src)[:16])"),
ac_version = ProtoField.uint16("airmax.ac.version", "Version"),
ac_src_mac = ProtoField.ether("airmax.ac.src_mac", "Source MAC"),
-- AC body: beacon
ac_mac_0c = ProtoField.ether("airmax.ac.mac_0c", "Radio MAC (mac_0c)"),
ac_cap = ProtoField.uint32("airmax.ac.cap_flags", "Capability Flags", base.HEX),
ac_cap_cbw = ProtoField.bool("airmax.ac.cap_flags.chanbw", "chanbw mode", 32, nil, 0x8),
ac_cap_hd = ProtoField.bool("airmax.ac.cap_flags.high_density", "high density", 32, nil, 0x10),
ac_cap_ad = ProtoField.bool("airmax.ac.cap_flags.auth_deauth", "auth-deauth capable", 32, nil, 0x40),
ac_cap_ax = ProtoField.bool("airmax.ac.cap_flags.compat_11ax", "11ax-compat", 32, nil, 0x80),
ac_mixed = ProtoField.uint32("airmax.ac.mixed_mode", "Mixed Mode"),
-- AC body: assoc_req / assoc_resp
ac_tx_chain = ProtoField.uint8("airmax.ac.tx_chainmask", "TX Chainmask"),
ac_rx_chain = ProtoField.uint8("airmax.ac.rx_chainmask", "RX Chainmask"),
ac_field14 = ProtoField.uint32("airmax.ac.field_14", "field_14 [open]", base.HEX),
ac_field9c = ProtoField.uint32("airmax.ac.field_9c", "field_9c [open]", base.HEX),
ac_ic6b8 = ProtoField.bytes("airmax.ac.ic_6b8", "ic_6b8 (chainmask pair)"),
ac_sta68 = ProtoField.uint32("airmax.ac.sta_field_68", "sta_field_68 [open]", base.HEX),
ac_rssi = ProtoField.bytes("airmax.ac.rssi", "RSSI (per-chain)"),
ac_txpower = ProtoField.uint8("airmax.ac.txpower", "TX Power (half-dBm)"),
-- AC body: deauth
ac_jiffies = ProtoField.uint32("airmax.ac.jiffies_nonce", "Jiffies Nonce", base.HEX),
ac_token = ProtoField.bytes("airmax.ac.enc_token", "Auth Token (opaque)"),
-- AC name / fw TLVs
ac_radio = ProtoField.string("airmax.ac.radioname", "Radioname"),
ac_ssid = ProtoField.string("airmax.ac.ssid", "SSID"),
ac_fwname = ProtoField.string("airmax.ac.fwname", "Firmware Name"),
ac_tlv_tag = ProtoField.uint8("airmax.ac.tlv.tag", "Tag", base.DEC, TLV_TAG_VS),
ac_tlv_len = ProtoField.uint8("airmax.ac.tlv.len", "Length"),
ac_tlv_data = ProtoField.bytes("airmax.ac.tlv.data", "Data"),
-- M outer (cleartext)
m_oui = ProtoField.bytes("airmax.m.oui", "OUI"),
m_oui_type = ProtoField.bytes("airmax.m.oui_type", "OUI Type"),
m_ct = ProtoField.bytes("airmax.m.ciphertext", "Ciphertext"),
-- M payload (decrypted)
m_key = ProtoField.string("airmax.m.key", "AES Key (HMAC-SHA1(dst,src)[:16])"),
m_version = ProtoField.uint8("airmax.m.version", "Version"),
m_msg_type = ProtoField.uint8("airmax.m.msg_type", "Message Type", base.DEC, M_MSG_VS),
m_src_mac = ProtoField.ether("airmax.m.src_mac", "Source MAC"),
m_enable = ProtoField.uint8("airmax.m.enable", "Enable"),
m_unknown = ProtoField.bytes("airmax.m.unknown_rest", "Unknown Rest"),
-- RouterBoard (cleartext)
rb_oui = ProtoField.bytes("airmax.rb.oui", "OUI"),
rb_oui_type = ProtoField.uint8("airmax.rb.oui_type", "OUI Type"),
rb_unknown = ProtoField.bytes("airmax.rb.unknown", "Unknown"),
rb_name = ProtoField.string("airmax.rb.device_name", "Device Name"),
rb_sub_type = ProtoField.uint8("airmax.rb.subie.subtype", "Subtype"),
rb_sub_len = ProtoField.uint8("airmax.rb.subie.length", "Length"),
rb_sub_data = ProtoField.bytes("airmax.rb.subie.data", "Data"),
}
local flist = {}
for _, pf in pairs(f) do flist[#flist + 1] = pf end
p_airmax.fields = flist
local e_decrypt = ProtoExpert.new("airmax.expert.decrypt", "Payload could not be decrypted",
expert.group.DECRYPTION, expert.severity.WARN)
local e_key = ProtoExpert.new("airmax.expert.key", "Embedded MAC mismatch (key may be wrong)",
expert.group.CHECKSUM, expert.severity.NOTE)
local e_short = ProtoExpert.new("airmax.expert.short", "Truncated or malformed AirMAX IE",
expert.group.MALFORMED, expert.severity.WARN)
p_airmax.experts = { e_decrypt, e_key, e_short }
-- Field extractors (must be created at load time).
local f_oui = Field.new("wlan.tag.oui")
local f_sa = Field.new("wlan.sa")
local f_da = Field.new("wlan.da")
-- ---------------------------------------------------------------------------
-- Helpers
-- ---------------------------------------------------------------------------
local function fi_raw(fi)
if fi then return fi.range:raw() end
return nil
end
local function dst_label(d)
if d == crypto.BROADCAST then return "broadcast" end
return util.mac(d)
end
-- Locate a vendor IE from its OUI FieldInfo. Returns (ie_tvbrange, off, len)
-- where `off` is the OUI offset in the frame tvb and the range covers the IE
-- body from the OUI to the end of the IE. nil if it isn't a tag-221 IE.
local function locate_ie(tvb, fi)
local off = fi.range:offset()
if off < 2 then return nil end
if tvb(off - 2, 1):uint() ~= 0xdd then return nil end -- not a Vendor Specific tag
local ielen = tvb(off - 1, 1):uint()
if off + ielen > tvb:len() then return nil end
return tvb(off, ielen), off, ielen
end
-- Decrypt + verify against the embedded source MAC, with broadcast fallback
-- (matches pyrmax.pcap._try_decode). Returns (pt, payload, dst_used, verified).
local function decrypt_verify(ciphertext, sa, da, parse_payload, embedded_mac)
if not sa then return nil end
local cands = {}
if da then cands[#cands + 1] = da end
if (not da) or da ~= crypto.BROADCAST then cands[#cands + 1] = crypto.BROADCAST end
local first_pt, first_payload, first_dst
for _, d in ipairs(cands) do
local ok, pt = pcall(crypto.decrypt, ciphertext, sa, d)
if ok then
local payload = parse_payload(pt)
if not first_pt then first_pt, first_payload, first_dst = pt, payload, d end
if payload and embedded_mac(payload) == sa then
return pt, payload, d, true
end
end
end
return first_pt, first_payload, first_dst, false
end
local function decrypted_node(parent, pt, name)
local ptvb = ByteArray.new(util.to_hex(pt)):tvb(name)
local node = parent:add(p_airmax, ptvb())
node:set_text("Decrypted payload (AES-128-ECB)")
node:set_generated()
return node, ptvb
end
-- Add a cap_flags u32 with its (partially known, §11) bit booleans.
local function add_ac_cap(dt, ptvb, cap)
local n = dt:add(f.ac_cap, ptvb(cap.o, 4))
n:add(f.ac_cap_cbw, ptvb(cap.o, 4))
n:add(f.ac_cap_hd, ptvb(cap.o, 4))
n:add(f.ac_cap_ad, ptvb(cap.o, 4))
n:add(f.ac_cap_ax, ptvb(cap.o, 4))
return n
end
-- Add the radioname/SSID string fields, then a subtree per name TLV. `tlvs`
-- carries radioname/ssid (+ a trailing Padding marker for beacons).
local function add_ac_tlvs(dt, ptvb, tlvs)
for _, t in ipairs(tlvs) do
if t.tag == 1 and #t.data > 0 then dt:add(f.ac_radio, ptvb(t.data_o, #t.data)) end
if t.tag == 2 and #t.data > 0 then dt:add(f.ac_ssid, ptvb(t.data_o, #t.data)) end
end
for _, t in ipairs(tlvs) do
if t.tag == 0 then
dt:add(p_airmax, ptvb(t.o, 1)):set_text("TLV: Padding (0)")
:add(f.ac_tlv_tag, ptvb(t.o, 1))
else
local tn = TLV_TAG_VS[t.tag] or string.format("0x%02x", t.tag)
local node = dt:add(p_airmax, ptvb(t.o, 2 + #t.data))
node:set_text(string.format("TLV: %s (%d), len %d", tn, t.tag, t.len))
node:add(f.ac_tlv_tag, ptvb(t.o, 1))
node:add(f.ac_tlv_len, ptvb(t.o + 1, 1))
if #t.data > 0 then node:add(f.ac_tlv_data, ptvb(t.data_o, #t.data)) end
end
end
end
-- Append the version-gated assoc tail (field_9c/sta_field_68, rssi, fwname,
-- txpower) shared between assoc_req and assoc_resp bodies.
local function add_ac_tail(dt, ptvb, body)
if body.field_9c then dt:add(f.ac_field9c, ptvb(body.field_9c.o, 4)) end
if body.sta_field_68 then dt:add(f.ac_sta68, ptvb(body.sta_field_68.o, 4)) end
if body.rssi then dt:add(f.ac_rssi, ptvb(body.rssi.o, 2)) end
if body.fwname then dt:add(f.ac_fwname, ptvb(body.fwname.data_o, #body.fwname.data)) end
if body.txpower then dt:add(f.ac_txpower, ptvb(body.txpower.o, 1)) end
end
-- ---------------------------------------------------------------------------
-- Per-variant handlers
-- ---------------------------------------------------------------------------
local function handle_ac(tvb, fi, sa, da, tree, pinfo)
local ierange, off = locate_ie(tvb, fi)
if not ierange then return end
local outer = ac.parse_outer(ierange:raw())
if not outer then return end
local st = tree:add(p_airmax, ierange)
st:set_text("AirMAX AC (Vendor Specific IE)")
st:add(f.ac_oui, tvb(off, 3))
st:add(f.ac_oui_type, tvb(off + 3, 3))
st:add(f.ac_flags, tvb(off + 6, 1)):add(f.ac_flag_enc, tvb(off + 6, 1))
st:add(f.ac_msg_type, tvb(off + 7, 1))
st:add(f.ac_enc_len, tvb(off + 8, 2))
local ct_off, ct_len = off + 10, outer.enc_len
st:add(f.ac_ct, tvb(ct_off, ct_len))
pinfo.cols.info:append(" | AirMAX-AC " .. (ac.MSG_TYPE[outer.msg_type] or outer.msg_type))
if (outer.flags & ac.FLAG_ENCRYPTED) == 0 then return end
local pt, payload, dst_used, verified = decrypt_verify(
outer.ciphertext, sa, da,
function(p) return ac.parse_payload(p, outer.msg_type) end,
function(pp) return pp.src_mac.val end)
if not pt then
st:add_proto_expert_info(e_decrypt, "needs the 802.11 source MAC for key derivation")
return
end
local dt, ptvb = decrypted_node(st, pt, "Decrypted AirMAX AC payload")
dt:add(f.ac_key, tvb(ct_off, ct_len),
util.to_hex(crypto.derive_key(sa, dst_used)) .. " (dst=" .. dst_label(dst_used) .. ")")
:set_generated()
if not verified then dt:add_proto_expert_info(e_key) end
if not payload then dt:add_proto_expert_info(e_short, "decrypted payload too short"); return end
-- Shared head
dt:add(f.ac_version, ptvb(0, 2))
local smac = dt:add(f.ac_src_mac, ptvb(2, 6))
-- Per-msg_type body
local body = payload.body
if body.kind == "beacon" then
dt:add(f.ac_mac_0c, ptvb(body.mac_0c.o, 6))
add_ac_cap(dt, ptvb, body.cap_flags)
dt:add(f.ac_mixed, ptvb(body.mixed_mode.o, 4))
add_ac_tlvs(dt, ptvb, body.tlvs)
elseif body.kind == "assoc_req" then
dt:add(f.ac_tx_chain, ptvb(body.tx_chainmask.o, 1))
dt:add(f.ac_rx_chain, ptvb(body.rx_chainmask.o, 1))
add_ac_cap(dt, ptvb, body.cap_flags)
dt:add(f.ac_field14, ptvb(body.field_14.o, 4))
add_ac_tlvs(dt, ptvb, body.tlvs)
add_ac_tail(dt, ptvb, body)
elseif body.kind == "assoc_resp" then
dt:add(f.ac_ic6b8, ptvb(body.ic_6b8.o, 2))
add_ac_tail(dt, ptvb, body)
elseif body.kind == "deauth" then
-- src_mac (above) is XOR-masked on the wire; show the recovered value.
smac:append_text(" (masked; real = " .. util.mac(payload.src_mac.val) .. ")")
dt:add(f.ac_jiffies, ptvb(body.jiffies_nonce.o, 4))
dt:add(f.ac_token, ptvb(body.enc_token.o, 16)):append_text(" (opaque — token key not reverse-engineered)")
elseif body.kind == "probe_req" then
dt:append_text(" (probe_req — header only)")
end
end
local function handle_m(tvb, fi, sa, da, tree, pinfo)
local ierange, off, ielen = locate_ie(tvb, fi)
if not ierange then return end
local outer = m.parse_outer(ierange:raw())
if not outer then return end
local st = tree:add(p_airmax, ierange)
st:set_text("AirMAX M (Vendor Specific IE)")
st:add(f.m_oui, tvb(off, 3))
st:add(f.m_oui_type, tvb(off + 3, 3))
st:add(f.m_ct, tvb(off + 6, ielen - 6))
pinfo.cols.info:append(" | AirMAX-M")
local pt, payload, dst_used, verified = decrypt_verify(
outer.ciphertext, sa, da, m.parse_payload,
function(pp) return pp.src_mac.val end)
if not pt then
st:add_proto_expert_info(e_decrypt, "needs the 802.11 source MAC for key derivation")
return
end
local dt, ptvb = decrypted_node(st, pt, "Decrypted AirMAX M payload")
dt:add(f.m_key, tvb(off + 6, ielen - 6),
util.to_hex(crypto.derive_key(sa, dst_used)) .. " (dst=" .. dst_label(dst_used) .. ")")
:set_generated()
if not verified then dt:add_proto_expert_info(e_key) end
if not payload then dt:add_proto_expert_info(e_short, "decrypted payload too short"); return end
dt:add(f.m_version, ptvb(0, 1))
dt:add(f.m_msg_type, ptvb(1, 1))
dt:add(f.m_src_mac, ptvb(2, 6))
dt:add(f.m_enable, ptvb(8, 1))
if payload.unknown_rest.l > 0 then dt:add(f.m_unknown, ptvb(9, payload.unknown_rest.l)) end
end
local function handle_rb(tvb, fi, tree, pinfo)
local ierange, off = locate_ie(tvb, fi)
if not ierange then return end
local parsed = rb.parse(ierange:raw())
if not parsed then return end
local st = tree:add(p_airmax, ierange)
st:set_text("Mikrotik / RouterBoard (Vendor Specific IE)")
st:add(f.rb_oui, tvb(off, 3))
st:add(f.rb_oui_type, tvb(off + 3, 1))
st:add(f.rb_unknown, tvb(off + 4, 2))
local name = rb.device_name(parsed)
if name then
st:add(f.rb_name, ierange, name):set_generated()
pinfo.cols.info:append(" | RB '" .. name .. "'")
end
for _, s in ipairs(parsed.sub_ies) do
local node = st:add(p_airmax, tvb(off + s.o, 2 + s.len))
node:set_text(string.format("Sub-IE: subtype %d, len %d", s.subtype, s.len))
node:add(f.rb_sub_type, tvb(off + s.o, 1))
node:add(f.rb_sub_len, tvb(off + s.o + 1, 1))
if s.len > 0 then node:add(f.rb_sub_data, tvb(off + s.o + 2, s.len)) end
end
end
-- ---------------------------------------------------------------------------
-- Postdissector
-- ---------------------------------------------------------------------------
function p_airmax.dissector(tvb, pinfo, tree)
local ouis = { f_oui() }
if #ouis == 0 then return end
local sa = fi_raw(f_sa())
local da = fi_raw(f_da())
for _, fi in ipairs(ouis) do
local v = fi.value
local ok, err
if v == OUI_AC then
ok, err = pcall(handle_ac, tvb, fi, sa, da, tree, pinfo)
elseif v == OUI_M then
ok, err = pcall(handle_m, tvb, fi, sa, da, tree, pinfo)
elseif v == OUI_RB then
ok, err = pcall(handle_rb, tvb, fi, tree, pinfo)
else
ok = true
end
if not ok then
local n = tree:add(p_airmax, fi.range)
n:set_text("AirMAX dissector error: " .. tostring(err))
n:add_proto_expert_info(e_short, tostring(err))
end
end
end
register_postdissector(p_airmax)
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