From 6e5cf2af31c04e7d0542be1b91e8a49147fc60a5 Mon Sep 17 00:00:00 2001 From: Thomas Lynch Date: Sat, 11 Feb 2023 20:55:30 +1100 Subject: [PATCH] Make cookie expiry based on issued expiry date from challenge date instead of all expiring on bucket. Fixes potential issue of challenges being incorrect if solved right on the bucket change Allows to solve a challenge at any time (even in the background) and not see the challenge page twice in a small period Allows for backend to make dynamic expiry of tokens e.g make tor tokens or based on IP reputation not last as long (not implemented atm) Close #20 --- src/lua/libs/utils.lua | 16 ++--- src/lua/scripts/bot-check.lua | 119 ++++++++++++++++++++-------------- src/lua/scripts/templates.lua | 2 +- 3 files changed, 81 insertions(+), 56 deletions(-) diff --git a/src/lua/libs/utils.lua b/src/lua/libs/utils.lua index b596f88..1160c7b 100644 --- a/src/lua/libs/utils.lua +++ b/src/lua/libs/utils.lua @@ -1,16 +1,12 @@ local _M = {} local sha = require("sha") -local secret_bucket_duration = tonumber(os.getenv("BUCKET_DURATION")) +local bucket_duration = tonumber(os.getenv("BUCKET_DURATION")) local challenge_includes_ip = os.getenv("CHALLENGE_INCLUDES_IP") local tor_control_port_password = os.getenv("TOR_CONTROL_PORT_PASSWORD") -- generate the challenge hash/user hash -function _M.generate_secret(context, salt, user_key, is_applet) - - -- time bucket for expiry - local start_sec = core.now()['sec'] - local bucket = start_sec - (start_sec % secret_bucket_duration) +function _M.generate_challenge(context, salt, user_key, is_applet) -- optional IP to lock challenges/user_keys to IP (for clearnet or single-onion aka 99% of cases) local ip = "" @@ -28,7 +24,11 @@ function _M.generate_secret(context, salt, user_key, is_applet) user_agent = context.sf:req_fhdr('user-agent') or "" end - return sha.sha3_256(salt .. bucket .. ip .. user_key .. user_agent) + local challenge_hash = sha.sha3_256(salt .. ip .. user_key .. user_agent) + + local expiry = core.now()['sec'] + bucket_duration + + return challenge_hash, expiry end @@ -59,7 +59,7 @@ end function _M.send_tor_control_port(circuit_identifier) local tcp = core.tcp(); tcp:settimeout(1); - tcp:connect("127.0.0.1", 9051); + tcp:connect("127.0.0.1", 9051); --TODO: configurable host/port -- not buffered, so we are better off sending it all at once tcp:send('AUTHENTICATE "' .. tor_control_port_password .. '"\nCLOSECIRCUIT ' .. circuit_identifier ..'\n') tcp:close() diff --git a/src/lua/scripts/bot-check.lua b/src/lua/scripts/bot-check.lua index 5785ee3..946b55f 100644 --- a/src/lua/scripts/bot-check.lua +++ b/src/lua/scripts/bot-check.lua @@ -116,9 +116,9 @@ function _M.view(applet) -- get the user_key#challenge#sig local user_key = sha.bin_to_hex(randbytes(16)) - local challenge_hash = utils.generate_secret(applet, pow_cookie_secret, user_key, true) - local signature = sha.hmac(sha.sha3_256, hmac_cookie_secret, user_key .. challenge_hash) - local combined_challenge = user_key .. "#" .. challenge_hash .. "#" .. signature + local challenge_hash, expiry = utils.generate_challenge(applet, pow_cookie_secret, user_key, true) + local signature = sha.hmac(sha.sha3_256, hmac_cookie_secret, user_key .. challenge_hash .. expiry) + local combined_challenge = user_key .. "#" .. challenge_hash .. "#" .. expiry .. "#" .. signature -- define body sections local site_name_body = "" @@ -144,8 +144,9 @@ function _M.view(applet) captcha_sitekey, captcha_script_src) else pow_body = templates.pow_section - noscript_extra_body = string.format(templates.noscript_extra, user_key, challenge_hash, signature, - math.ceil(pow_difficulty/8), argon_time, argon_kb) + noscript_extra_body = string.format(templates.noscript_extra, user_key, + challenge_hash, expiry, signature, math.ceil(pow_difficulty/8), + argon_time, argon_kb) end -- sub in the body sections @@ -171,47 +172,57 @@ function _M.view(applet) -- handle setting the POW cookie local user_pow_response = parsed_body["pow_response"] + local matched_expiry = 0 -- ensure captcha cookie expiry matches POW cookie if user_pow_response then -- split the response up (makes the nojs submission easier because it can be a single field) local split_response = utils.split(user_pow_response, "#") - if #split_response == 4 then + if #split_response == 5 then local given_user_key = split_response[1] local given_challenge_hash = split_response[2] - local given_signature = split_response[3] - local given_answer = split_response[4] + local given_expiry = split_response[3] + local given_signature = split_response[4] + local given_answer = split_response[5] - -- regenerate the challenge and compare it - local generated_challenge_hash = utils.generate_secret(applet, pow_cookie_secret, given_user_key, true) - if given_challenge_hash == generated_challenge_hash then + -- expiry check + local number_expiry = tonumber(given_expiry, 10) + if number_expiry ~= nil and number_expiry > core.now()['sec'] then - -- regenerate the signature and compare it - local generated_signature = sha.hmac(sha.sha3_256, hmac_cookie_secret, given_user_key .. given_challenge_hash) - if given_signature == generated_signature then + -- regenerate the challenge and compare it + local generated_challenge_hash = utils.generate_challenge(applet, pow_cookie_secret, given_user_key, true) - -- do the work with their given answer - local full_hash = argon2.hash_encoded(given_challenge_hash .. given_answer, given_user_key) + if given_challenge_hash == generated_challenge_hash then - -- check the output is correct - local hash_output = utils.split(full_hash, '$')[6]:sub(0, 43) -- https://github.com/thibaultcha/lua-argon2/issues/37 - local hex_hash_output = sha.bin_to_hex(sha.base64_to_bin(hash_output)); - if utils.checkdiff(hex_hash_output, pow_difficulty) then + -- regenerate the signature and compare it + local generated_signature = sha.hmac(sha.sha3_256, hmac_cookie_secret, given_user_key .. given_challenge_hash .. given_expiry) - -- the answer was good, give them a cookie - local signature = sha.hmac(sha.sha3_256, hmac_cookie_secret, given_user_key .. given_challenge_hash .. given_answer) - local combined_cookie = given_user_key .. "#" .. given_challenge_hash .. "#" .. given_answer .. "#" .. signature - applet:add_header( - "set-cookie", - string.format( - "z_ddos_pow=%s; Expires=Thu, 31-Dec-37 23:55:55 GMT; Path=/; Domain=.%s; SameSite=Strict;%s", - combined_cookie, - applet.headers['host'][0], - secure_cookie_flag + if given_signature == generated_signature then + + -- do the work with their given answer + local full_hash = argon2.hash_encoded(given_challenge_hash .. given_answer, given_user_key) + + -- check the output is correct + local hash_output = utils.split(full_hash, '$')[6]:sub(0, 43) -- https://github.com/thibaultcha/lua-argon2/issues/37 + local hex_hash_output = sha.bin_to_hex(sha.base64_to_bin(hash_output)); + + if utils.checkdiff(hex_hash_output, pow_difficulty) then + + -- the answer was good, give them a cookie + local signature = sha.hmac(sha.sha3_256, hmac_cookie_secret, given_user_key .. given_challenge_hash .. given_expiry .. given_answer) + local combined_cookie = given_user_key .. "#" .. given_challenge_hash .. "#" .. given_expiry .. "#" .. given_answer .. "#" .. signature + applet:add_header( + "set-cookie", + string.format( + "_basedflare_pow=%s; Expires=Thu, 31-Dec-37 23:55:55 GMT; Path=/; Domain=.%s; SameSite=Strict;%s", + combined_cookie, + applet.headers['host'][0], + secure_cookie_flag + ) ) - ) - valid_submission = true + valid_submission = true + end end end end @@ -251,13 +262,13 @@ function _M.view(applet) if api_response.success == true then local user_key = sha.bin_to_hex(randbytes(16)) - local user_hash = utils.generate_secret(applet, captcha_cookie_secret, user_key, true) - local signature = sha.hmac(sha.sha3_256, hmac_cookie_secret, user_key .. user_hash) - local combined_cookie = user_key .. "#" .. user_hash .. "#" .. signature + local user_hash = utils.generate_challenge(applet, captcha_cookie_secret, user_key, true) + local signature = sha.hmac(sha.sha3_256, hmac_cookie_secret, user_key .. user_hash .. matched_expiry) + local combined_cookie = user_key .. "#" .. user_hash .. "#" .. matched_expiry .. "#" .. signature applet:add_header( "set-cookie", string.format( - "z_ddos_captcha=%s; Expires=Thu, 31-Dec-37 23:55:55 GMT; Path=/; Domain=.%s; SameSite=Strict;%s", + "_basedflare_captcha=%s; Expires=Thu, 31-Dec-37 23:55:55 GMT; Path=/; Domain=.%s; SameSite=Strict;%s", combined_cookie, applet.headers['host'][0], secure_cookie_flag @@ -309,22 +320,29 @@ end -- check if captcha cookie is valid, separate secret from POW function _M.check_captcha_status(txn) local parsed_request_cookies = cookie.get_cookie_table(txn.sf:hdr("Cookie")) - local received_captcha_cookie = parsed_request_cookies["z_ddos_captcha"] or "" + local received_captcha_cookie = parsed_request_cookies["_basedflare_captcha"] or "" -- split the cookie up local split_cookie = utils.split(received_captcha_cookie, "#") - if #split_cookie ~= 3 then + if #split_cookie ~= 4 then return end local given_user_key = split_cookie[1] local given_user_hash = split_cookie[2] - local given_signature = split_cookie[3] + local given_expiry = split_cookie[3] + local given_signature = split_cookie[4] + + -- expiry check + local number_expiry = tonumber(given_expiry, 10) + if number_expiry == nil or number_expiry <= core.now()['sec'] then + return + end -- regenerate the user hash and compare it - local generated_user_hash = utils.generate_secret(txn, captcha_cookie_secret, given_user_key, false) + local generated_user_hash = utils.generate_challenge(txn, captcha_cookie_secret, given_user_key, false) if generated_user_hash ~= given_user_hash then return end -- regenerate the signature and compare it - local generated_signature = sha.hmac(sha.sha3_256, hmac_cookie_secret, given_user_key .. given_user_hash) + local generated_signature = sha.hmac(sha.sha3_256, hmac_cookie_secret, given_user_key .. given_user_hash .. given_expiry) if given_signature == generated_signature then return txn:set_var("txn.captcha_passed", true) end @@ -333,23 +351,30 @@ end -- check if pow cookie is valid function _M.check_pow_status(txn) local parsed_request_cookies = cookie.get_cookie_table(txn.sf:hdr("Cookie")) - local received_pow_cookie = parsed_request_cookies["z_ddos_pow"] or "" + local received_pow_cookie = parsed_request_cookies["_basedflare_pow"] or "" -- split the cookie up local split_cookie = utils.split(received_pow_cookie, "#") - if #split_cookie ~= 4 then + if #split_cookie ~= 5 then return end local given_user_key = split_cookie[1] local given_challenge_hash = split_cookie[2] - local given_answer = split_cookie[3] - local given_signature = split_cookie[4] + local given_expiry = split_cookie[3] + local given_answer = split_cookie[4] + local given_signature = split_cookie[5] + + -- expiry check + local number_expiry = tonumber(given_expiry, 10) + if number_expiry == nil or number_expiry <= core.now()['sec'] then + return + end -- regenerate the challenge and compare it - local generated_challenge_hash = utils.generate_secret(txn, pow_cookie_secret, given_user_key, false) + local generated_challenge_hash = utils.generate_challenge(txn, pow_cookie_secret, given_user_key, false) if given_challenge_hash ~= generated_challenge_hash then return end -- regenerate the signature and compare it - local generated_signature = sha.hmac(sha.sha3_256, hmac_cookie_secret, given_user_key .. given_challenge_hash .. given_answer) + local generated_signature = sha.hmac(sha.sha3_256, hmac_cookie_secret, given_user_key .. given_challenge_hash .. given_expiry .. given_answer) if given_signature == generated_signature then return txn:set_var("txn.pow_passed", true) end diff --git a/src/lua/scripts/templates.lua b/src/lua/scripts/templates.lua index e223f27..02fadb5 100644 --- a/src/lua/scripts/templates.lua +++ b/src/lua/scripts/templates.lua @@ -57,7 +57,7 @@ _M.noscript_extra = [[

  • Run this in a linux terminal (requires argon2 package installed):

    - echo "Q0g9IiQyIjtCPSQocHJpbnRmICcwJS4wcycgJChzZXEgMSAkNCkpO2VjaG8gIldvcmtpbmcuLi4iO0k9MDt3aGlsZSB0cnVlOyBkbyBIPSQoZWNobyAtbiAkQ0gkSSB8IGFyZ29uMiAkMSAtaWQgLXQgJDUgLWsgJDYgLXAgMSAtbCAzMiAtcik7RT0ke0g6MDokNH07W1sgJEUgPT0gJEIgXV0gJiYgZWNobyAiT3V0cHV0OiIgJiYgZWNobyAkMSMkMiMkMyMkSSAmJiBleGl0IDA7KChJKyspKTtkb25lOwo=" | base64 -d | bash -s %s %s %s %s %s %s + echo "Q0g9IiQyIjtCPSQocHJpbnRmIDAlLjBzICQoc2VxIDEgJDUpKTtlY2hvICJXb3JraW5nLi4uIjtJPTA7d2hpbGUgdHJ1ZTsgZG8gSD0kKGVjaG8gLW4gJENIJEkgfCBhcmdvbjIgJDEgLWlkIC10ICQ2IC1rICQ3IC1wIDEgLWwgMzIgLXIpO0U9JHtIOjA6JDV9O1tbICRFID09ICRCIF1dICYmIGVjaG8gIk91dHB1dDoiICYmIGVjaG8gJDEjJDIjJDMjJDQjJEkgJiYgZXhpdCAwOygoSSsrKSk7ZG9uZTsK" | base64 -d | bash -s %s %s %s %s %s %s %s
  • Paste the script output into the box and submit: