[Rules] Add dedicated bitcoin addresses filter rule

1 files changed, 86 insertions, 0 deletions

diff --git a/rules/bitcoin.lua b/rules/bitcoin.lua
new file mode 100644
index 000000000..df6fed2f6
--- /dev/null
+++ b/rules/bitcoin.lua
@@ -0,0 +1,86 @@
+--[[
+Copyright (c) 2019, Vsevolod Stakhov <vsevolod@highsecure.ru>
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+]]--
+
+-- Bitcoin filter rules
+
+local fun = require "fun"
+local off = 0
+local base58_dec = fun.tomap(fun.map(
+    function(c)
+      off = off + 1
+      return c,(off - 1)
+    end,
+    "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"))
+
+rspamd_config:register_symbol{
+  name = 'BITCOIN_ADDR',
+  callback = function(task)
+    local rspamd_re = require "rspamd_regexp"
+    local hash = require "rspamd_cryptobox_hash"
+
+    local wallet_re = rspamd_re.create_cached('^[13][1-9A-Za-z]{25,34}$')
+    local words_matched = {}
+    local valid_wallets = {}
+
+    for _,part in ipairs(task:get_text_parts() or {}) do
+      local pw = part:filter_words(wallet_re, 'raw', 3)
+
+      if pw and #pw > 0 then
+        for _,w in ipairs(pw) do
+          words_matched[#words_matched + 1] = w
+        end
+      end
+    end
+
+    for _,word in ipairs(words_matched) do
+      local bytes = {}
+      for i=1,25 do bytes[i] = 0 end
+      -- Base58 decode loop
+      fun.each(function(ch)
+        local acc = base58_dec[ch] or 0
+        for i=25,1,-1 do
+          acc = acc + (58 * bytes[i]);
+          bytes[i] = acc % 256
+          acc = math.floor(acc / 256);
+        end
+      end, word)
+      -- Now create a validation tag
+      local sha256 = hash.create_specific('sha256')
+      for i=1,21 do
+        sha256:update(string.char(bytes[i]))
+      end
+      sha256 = hash.create_specific('sha256', sha256:bin()):bin()
+
+      -- Compare tags
+      local valid = true
+      for i=1,4 do
+        if string.sub(sha256, i, i) ~= string.char(bytes[21 + i]) then
+          valid = false
+        end
+      end
+
+      if valid then
+        valid_wallets[#valid_wallets + 1] = word
+      end
+    end
+
+    if #valid_wallets > 0 then
+      return true,1.0,valid_wallets
+    end
+  end,
+  score = 0.0,
+  group = 'scams'
+}
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