Haiyahhh Hack Vault

Network Printer Credential Capture

2 min read

🧠 Network Printer Credential Capture

What is it?

  • Concept: Enterprise network printers/scanners (and similar embedded devices) commonly ship with a web admin panel that stores a service account’s credentials so the device can query LDAP for the address book or authenticate to SMB to drop scanned files on a user’s share. That configuration page usually lets anyone who can reach it change the target server address.
  • Impact: Plaintext domain credential disclosure, achieved by making the device authenticate to an attacker-controlled listener instead of the real directory/file server — no exploit needed, just a config field and a netcat listener.

How it works

  1. The device’s admin panel exposes a settings page with fields for the LDAP/SMB server address, port, username, and (masked, but already-saved) password.
  2. Since the “server” is just whatever address is typed into that field, pointing it at an attacker-controlled IP makes the device connect there instead of the legitimate domain controller/file server on its next credential check.
  3. Devices that speak LDAP typically authenticate with a simple bind, which sends the username and password in the clear (or trivially decodable Base64) as soon as the TCP connection opens — a plain nc listener on the target port is enough to capture the full credential.

Exploitation

Prerequisites

  • Network access to the device’s admin web panel
  • Ability to edit the LDAP/SMB server address field (often unauthenticated or using default creds)

Attack Vectors

# Stand up a listener on the LDAP port before saving the new server address
sudo nc -lvnp 389

Then set Server Address to your tun0/attacker IP in the panel’s Settings page and save — the device reconnects immediately and the bind credentials land in the listener.

Notes

  • Works identically for SMB (port 445) or any other protocol the device supports specifying a custom server for — LDAP is just the common case because it’s usually configured for address-book lookups and rarely monitored.
  • The captured credential is often a low-privilege service account, but it’s frequently valid for WinRM/RDP directly, or turns out to hold interesting group memberships (e.g. built-in privileged groups) once you’re authenticated.

Mitigation

  • Fix: Don’t expose device admin panels on general network segments; where the server-address field can’t be locked down, restrict outbound LDAP/SMB from the device’s VLAN to only the legitimate directory/file server IP.
FileCreated
HTB - ReturnWednesday, July 22nd 2026, 2:55:00 am

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