From 929a29d310efea90666feff62c20eb629caa5226 Mon Sep 17 00:00:00 2001
From: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Mon, 3 Jun 2024 19:00:29 +0000
Subject: [PATCH] Fix a crash in rpc-grind when scanning a non-RPC service

---
 scripts/rpc-grind.nse | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/scripts/rpc-grind.nse b/scripts/rpc-grind.nse
index a89067b53..ce9996856 100644
--- a/scripts/rpc-grind.nse
+++ b/scripts/rpc-grind.nse
@@ -103,12 +103,14 @@ local isRPC = function(host, port)
       -- If we got response, set port to open
       nmap.set_port_state(host, port, "open")
 
-      rxid, msgtype = string.unpack(">I4 I4", data)
-      -- If response XID does match request XID
-      -- and message type equals 1 (REPLY) then
-      -- it is a RPC port.
-      if rxid == xid and msgtype == 1 then
-        return true
+      if #data >= 8 then
+        rxid, msgtype = string.unpack(">I4 I4", data)
+        -- If response XID does match request XID
+        -- and message type equals 1 (REPLY) then
+        -- it is a RPC port.
+        if rxid == xid and msgtype == 1 then
+          return true
+        end
       end
     end
   end