STG Security Advisory: [SSA-20050120-22] JSBoard file disclosure vulnerability

[<advisory () stgsecurity com>]

STG Security Advisory: [SSA-20050120-22] JSBoard file disclosure
vulnerability.

Revision 1.0
Date Published: 2005-01-20 (KST)
Last Update: 2005-01-20 (KST)
Disclosed by SSR Team (advisory () stgsecurity com)

Summary
========
JSBoard is one of widely used web BBS applications in Korea. Because of an
input validation flaw, a malicious attacker can read arbitrary files.

Vulnerability Class
===================
Implementation Error: Input validation flaw

Impact
======
Medium : arbitrary file disclosure

Affected Products
================
JSBoard 2.0.9 and prior.

Vendor Status: FIXED
====================
2004-12-31 Vulnerability found.
2004-12-31 JSBoard developer notified.
2005-01-02 Developer confirmed.
2005-01-02 Update version released.
2005-01-20 Official release.

Details
=======
PHP has a feature discarding the input values containing null characters
when magic_quotes_gpc = off. Because JSBoard session.php doesn't sanitize
$table variable, a malicious attacker can read arbitrary files.

- ---
include_once "include/print.php";
parse_query_str();
$opt = $table ? "&table=$table" : "";
$opts = $table ? "?table=$table" : "";
...snip...
- ---

Proof of Concept
================
A local web proxy (e.g., Achilles) is required to prove the vulnerability.

http://[victim]/session.php?logins=true&m=logout&table=../../../../../../etc
/passwd%00

Solution
=========
Upgrade to 2.0.10
http://kldp.net/frs/download.php/1729/jsboard-2.0.10.tar.gz

Vendor URL
==========
http://kldp.net/projects/jsboard/

Credits
======
Jeremy Bae at STG Security