Add ssl-cert-intaddr. Closes #557

CHANGELOG

@@ -1,5 +1,8 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o [NSE][GH#557] Script ssl-cert-intaddr will search for private IP addresses in
+  TLS certificate fields and extensions. [Steve Benson]
+
 o [GH#316] Added scan resume from Nmap's XML output. Now you can --resume a
   canceled scan from all 3 major output formats: -oN, -oG, and -oX.
   [Tudor Emil Coman]

scripts/script.db

@@ -484,6 +484,7 @@ Entry { filename = "ssh-hostkey.nse", categories = { "default", "discovery", "sa
 Entry { filename = "ssh2-enum-algos.nse", categories = { "discovery", "safe", } }
 Entry { filename = "sshv1.nse", categories = { "default", "safe", } }
 Entry { filename = "ssl-ccs-injection.nse", categories = { "safe", "vuln", } }
+Entry { filename = "ssl-cert-intaddr.nse", categories = { "discovery", "safe", "vuln", } }
 Entry { filename = "ssl-cert.nse", categories = { "default", "discovery", "safe", } }
 Entry { filename = "ssl-date.nse", categories = { "default", "discovery", "safe", } }
 Entry { filename = "ssl-dh-params.nse", categories = { "safe", "vuln", } }

scripts/ssl-cert-intaddr.nse

@@ -0,0 +1,146 @@
+local nmap = require "nmap"
+local shortport = require "shortport"
+local sslcert = require "sslcert"
+local stdnse = require "stdnse"
+local string = require "string"
+local ipOps = require "ipOps"
+
+description = [[
+Reports any private (RFC1918) IPv4 addresses found in the various fields of
+an SSL service's certificate.  These will only be reported if the target
+address itself is not private.  Nmap v7.30 or later is required.
+]]
+
+---
+-- @usage
+-- nmap -p 443 --script ssl-cert-intaddr <target>
+--
+-- @output
+-- 443/tcp open  https
+-- | ssl-cert-intaddr:
+-- |   Subject commonName:
+-- |     10.5.5.5
+-- |   Subject organizationName:
+-- |     10.0.2.1
+-- |     10.0.2.2
+-- |   Issuer emailAddress:
+-- |_    10.6.6.6
+-- |   X509v3 Subject Alternative Name:
+-- |_    10.3.4.5
+--
+--@xmloutput
+-- <table key="X509v3 Subject Alternative Name">
+--   <elem>10.3.4.5</elem>
+-- </table>
+---
+
+author = "Steve Benson"
+license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
+categories = {"vuln", "discovery", "safe"}
+
+-- only run this script if the target host is NOT a private (RFC1918) IP address)
+-- and the port is an open SSL service
+portrule = function(host, port)
+  if ipOps.isPrivate(host.ip) then
+    stdnse.debug1("%s is a private address - skipping.", host.ip)
+    return false
+  else
+    -- same criteria as ssl-cert.nse
+    return shortport.ssl(host, port) or sslcert.isPortSupported(port) or sslcert.getPrepareTLSWithoutReconnect(port)
+  end
+end
+
+-- extracts any valid private (RFC1918) IPv4 addresses from any given string
+-- returns a table containing them or nil if there were none found
+local extractPrivateIPv4Addr = function(s)
+  stdnse.debug2(" extractIPv4Addr: %s", s)
+
+  local addrs = {}
+
+  string.gsub(s, "%f[%d][12]?%d?%d%.[12]?%d?%d%.[12]?%d?%d%.[12]?%d?%d%f[^%d]",
+    function(match)
+      stdnse.debug2("  pattern match: %s", match)
+      if ipOps.isPrivate(match) then
+        stdnse.debug2("  is private (HIT): %s", match)
+        addrs[#addrs + 1] = match
+      end
+    end)
+
+  if #addrs>0 then
+    return addrs
+  else
+    return nil
+  end
+end
+
+-- search the Subject or Issuer fields for leaked private IP addresses
+local searchCertField = function(certField, certFieldName)
+  local k,v
+  local leaks = stdnse.output_table()
+
+  if certField then
+    for k,v in pairs(certField) do
+
+      -- if the name of this X509 field is numeric object identifier
+      -- (i.e.  "1.2.33.4..")
+      if type(k)=="table" then
+        k = stdnse.strjoin(".", k)
+      end
+
+      stdnse.debug2("search %s %s", certFieldName, k)
+      leaks[certFieldName.." "..k] = extractPrivateIPv4Addr(v)
+    end
+  end
+
+  return leaks
+end
+
+-- search the X509v3 extensions for leaked private IP addresses
+local searchCertExtensions = function(cert)
+  if not cert.extensions then
+    stdnse.debug1("X509v3 extensions not present in certificate or the extensions are not supported by this nmap version (7.30 or later needed)")
+    return {}
+  end
+
+  local exti, ext, _
+  local leaks = stdnse.output_table()
+
+  for _ ,ext in pairs(cert.extensions) do
+    if ext.value then
+      stdnse.debug2("search ext %s", ext.name)
+      leaks[ext.name] = extractPrivateIPv4Addr(ext.value)
+    else
+      stdnse.debug2("nosearch nil ext: %s", ext.name)
+    end
+  end
+
+  return leaks
+end
+
+action = function(host, port)
+  local ok, cert = sslcert.getCertificate(host, port)
+  if not ok then
+    stdnse.debug1("failed to obtain SSL certificate")
+    return nil
+  end
+
+  local leaks = stdnse.output_table()
+
+  for k,v in pairs(searchCertField(cert.subject, "Subject")) do
+    leaks[k] = v
+  end
+
+  for k,v in pairs(searchCertField(cert.issuer, "Issuer")) do
+    leaks[k] = v
+  end
+
+  for k,v in pairs(searchCertExtensions(cert)) do
+    leaks[k] = v
+  end
+
+  if #leaks > 0 then
+    return leaks
+  else
+    return nil
+  end
+end