STG Security Advisory: [SSA-20030701-03] ChangshinSoft ezTrans Server File
Download Vulnerability

Revision 1.1
Date Published: 2003-07-08 (KST)
Last Update: 2003-07-08
Disclosed by SSR Team (advisory@stgsecurity.com)


Synopsis
========
ezTrans Server, used by famous portal sites in Korea, is a real-time
Korean-to-Japanese and Japanese-to-Korean translator made by ChangshinSoft.
For inappropriate input validation in a file download module of ezTrans
Server, an attacker can download files accessible to web server privilege.

Vulnerability Class
===================
Implementation Error: Inappropriate Input Validation

Details
=======
For inappropriate input validation in a file download module of ezTrans
Server, an attacker can download files accessible to web server privilege.

Proof of Concept:
http://[victim
site]/question/crm/download.php?filename=../../../../../../../../../../../..
/etc/passwd

http://[victim
site]/download.php?filename=../../../../../../../../../../../../../etc/passw
d

Exploiting this vulnerability, an attacker can download files which
include critical information and damage a portal site with another
vulnerable web application.

Impact
======
An attacker can read critical information on the victim site.
Using this vulnerability and exploiting another vulnerable web applications,
a malicious attacker can dispossess a web server.

Workaround
==========
It's very difficult to program secure web applications in PHP. Nonetheless
you can minimize security problems by setting php.ini up appropriately.

To minimize the effects of this vulnerability, we recommend following
workarounds.

1. Turn register_globals option in php.ini OFF. For detailed information,
   refer to below sites.
2. Delete the vulnerable download.php and use static link to a file
   to download inside your HTML source.

References
Study in Scarlet - http://www.securereality.com.au/studyinscarlet.txt
Securing PHP: Step-by-step - http://www.securityfocus.com/infocus/1706

Affected Products
================
ezTrans Server

Vendor Status: FIXED
===================
2003-06-24 CSSoft notified.
2003-06-26 Second attempt at vendor and system administrator contact.
2003-07-02 Third attempt at vendor contact.
2003-07-04 Forth attempt at vendor contact.
2003-07-04 Vendor replied.
2003-07-04 Last attempt at vendor contact.
2003-07-04 Vendor fixed.
2003-07-08 Public disclosure


Credits
======
Jeremy Bae at STG Security SSR Team

About STG Security
=================
STG Security Inc. is a affiliated company of STG Group which has its head
office in the States founded in march 2000. Its core business area is
professional penetration testing, security code review and BS7799 consulting
services.

http://www.stgsecurity.com/

Phone +82-2-6333-4500
FAX +82-2-6333-4545