From bc0935a51a8a10e710a5601e300a4981612f9fc4 Mon Sep 17 00:00:00 2001
From: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Mon, 27 Aug 2018 15:02:48 +0000
Subject: [PATCH] Warn if no ciphers support FS. See #1309

---
 nselib/tls.lua               | 8 ++++++++
 scripts/ssl-enum-ciphers.nse | 3 +++
 2 files changed, 11 insertions(+)

diff --git a/nselib/tls.lua b/nselib/tls.lua
index c3d441b40..9e4a0f468 100644
--- a/nselib/tls.lua
+++ b/nselib/tls.lua
@@ -897,6 +897,7 @@ KEX_ALGORITHMS.RSA_EXPORT1024 = KEX_ALGORITHMS.RSA_EXPORT
 KEX_ALGORITHMS.DHE_RSA={
   pubkey="rsa",
   type = "dh",
+  pfs = true,
   server_key_exchange = function (blob, protocol)
     local pos
     local ret = {}
@@ -909,17 +910,20 @@ KEX_ALGORITHMS.DHE_RSA_EXPORT={
   export=true,
   pubkey="rsa",
   type = "dh",
+  pfs = true,
   server_key_exchange = KEX_ALGORITHMS.DHE_RSA.server_key_exchange
 }
 KEX_ALGORITHMS.DHE_DSS={
   pubkey="dsa",
   type = "dh",
+  pfs = true,
   server_key_exchange = KEX_ALGORITHMS.DHE_RSA.server_key_exchange
 }
 KEX_ALGORITHMS.DHE_DSS_EXPORT={
   export=true,
   pubkey="dsa",
   type = "dh",
+  pfs = true,
   server_key_exchange = KEX_ALGORITHMS.DHE_RSA.server_key_exchange
 }
 KEX_ALGORITHMS.DHE_DSS_EXPORT1024 = KEX_ALGORITHMS.DHE_DSS_EXPORT1024
@@ -942,6 +946,7 @@ KEX_ALGORITHMS.DH_RSA_EXPORT={
 KEX_ALGORITHMS.ECDHE_RSA={
   pubkey="rsa",
   type = "ec",
+  pfs = true,
   server_key_exchange = function (blob, protocol)
     local pos
     local ret = {}
@@ -953,6 +958,7 @@ KEX_ALGORITHMS.ECDHE_RSA={
 KEX_ALGORITHMS.ECDHE_ECDSA={
   pubkey="ec",
   type = "ec",
+  pfs = true,
   server_key_exchange = KEX_ALGORITHMS.ECDHE_RSA.server_key_exchange
 }
 KEX_ALGORITHMS.ECDH_ECDSA={
@@ -995,6 +1001,7 @@ KEX_ALGORITHMS.RSA_PSK = {
 }
 KEX_ALGORITHMS.DHE_PSK = {
   type = "dh",
+  pfs = true,
   server_key_exchange = function (blob, protocol)
     local pos
     local ret = {}
@@ -1009,6 +1016,7 @@ KEX_ALGORITHMS.PSK_DHE = KEX_ALGORITHMS.DHE_PSK
 --rfc5489
 KEX_ALGORITHMS.ECDHE_PSK={
   type = "ec",
+  pfs = true,
   server_key_exchange = function (blob, protocol)
     local pos
     local ret = {}
diff --git a/scripts/ssl-enum-ciphers.nse b/scripts/ssl-enum-ciphers.nse
index b84854239..c5a918028 100644
--- a/scripts/ssl-enum-ciphers.nse
+++ b/scripts/ssl-enum-ciphers.nse
@@ -675,6 +675,7 @@ local function find_ciphers_group(host, port, protocol, group, scores)
               scores.warnings["Broken cipher RC4 is deprecated by RFC 7465"] = true
             end
             local kex = tls.KEX_ALGORITHMS[info.kex]
+            scores.any_pfs_ciphers = kex.pfs or scores.any_pfs_ciphers
             local extra, kex_strength
             if kex.anon then
               kex_strength = 0
@@ -815,6 +816,8 @@ local function find_ciphers(host, port, protocol)
     end
   end
   if not next(results) then return nil end
+  scores.warnings["Forward Secrecy not supported by any cipher"] = (not scores.any_pfs_ciphers) or nil
+  scores.any_pfs_ciphers = nil
 
   return results, scores
 end