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Advisory: GNUboard SQL Injection Vulnerability
Author: claepo.wang@dbappsecurity.com.cn
Affected Version: GNUboard5(the latest version)
Vendor URL: http://sir.co.kr/
Vendor Status: Unfixed(I know little about Korean，so i do not know how to describe this vul to the vendor.)


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Vulnerability Description
==========================

Recently, I found several vulnerabilities in the famous Korean forum program - the GNUboard.


Vulnerable file: /bbs/ajax.autosave.php


<?php
include_once('./_common.php’);//global ‘filter' on $_GET,$_POST,$_COOKIE,$_REQUEST

if (!$is_member) die('0’);//member login

$uid     = trim($_REQUEST['uid']); //current user id
$subject = trim(stripslashes($_REQUEST['subject']));  //stripslashes ignores the global filter causes a SQL Inj.
$content = trim(stripslashes($_REQUEST['content']));  //same above

if ($subject && $content) {
    $sql = " select count(*) as cnt from {$g5['autosave_table']} where mb_id = '{$member['mb_id']}' and as_subject = '$subject' and as_content = '$content' ";
    $row = sql_fetch($sql); //the bad str($subject|$content) insert into sql query

    if (!$row['cnt']) {
        $sql = " insert into {$g5['autosave_table']} set mb_id = '{$member['mb_id']}', as_uid = '{$uid}', as_subject = '$subject', as_content = '$content', as_datetime = '".G5_TIME_YMDHIS."' on duplicate key update as_subject = '$subject', as_content = '$content', as_datetime = '".G5_TIME_YMDHIS."' ";
        $result = sql_query($sql, false);  // database select

        echo autosave_count($member['mb_id']);
    }
}
?>

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POC && EXP
==========================

1. Login as a member

2. GET http://target/bbs/ajax.autosave.php?content=1&subject=1[inj_exp]
{exp can be found on my server: http://pandas.pw/gnuboard.exp}
3. Page returns 1062 : Duplicate entry ~admin~*FF6F916236F4FFEE8FADD21EC20216C5C3A04E50~1' for key 'group_key’ .

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Done! Thx a lot!