0x01 背景
现在的WEB程序基本都有对SQL注入的全局过滤,像PHP开启了GPC或者在全局文件common.php上使用addslashes()函数对接收的参数进行过滤,尤其是单引号。二次注入也是一种比较常见的注入,它涉及到入库和出库。因为有全局转义所以入库的时候:
Insert into table (username) values (‘hack\’’);
这样入库后转义符就会消失变成了hack’,这样如果hack’出库被带入查询的话就会成功的引入了单引号导致注入。
漏洞来源于乌云: http://www.wooyun.org/bugs/wooyun-2014-068362
0x02 环境搭建
看背景我们使用了低版本的74cms程序,版本为3.4(20140310)
①源码网上可以搜到,我打包了一份: http://pan.baidu.com/s/1c1mLCru
②解压到www的74cms(20140310)目录下,浏览器访问 http://localhost/74cms(20140310) ),然后按照提示一步步安装即可,安装遇到问题请自行百度或谷歌,成功后访问如下图:
0x03 漏洞分析
Part1:源码结构
源码的结构比较清晰,应该是审计过最清晰的结构了,主要有下面三块内容:
index.php引入了common.inc.php文件,我们跟进common.inc.php,发现了处理gpc的函数:
if (!empty($_GET)){$_GET = addslashes_deep($_GET);}if (!empty($_POST)){$_POST = addslashes_deep($_POST);}$_COOKIE = addslashes_deep($_COOKIE);$_REQUEST = addslashes_deep($_REQUEST);
可以看到,服务端处理GET和POST请求的变量时都会做addslashes处理。
Part2:审计过程
1.首先在个人发布简历处:
elseif ($act=='make4_save'){$resume_education=get_resume_education($_SESSION['uid'],$_REQUEST['pid']);if (count($resume_education)>=6) showmsg('教育经历不能超过6条!',1,$link);$setsqlarr['uid']=intval($_SESSION['uid']);$setsqlarr['pid']=intval($_REQUEST['pid']);if ($setsqlarr['uid']==0 || $setsqlarr['pid']==0 ) showmsg('参数错误!',1);$setsqlarr['start']=trim($_POST['start'])?$_POST['start']:showmsg('请填写开始时间!',1,$link);$setsqlarr['endtime']=trim($_POST['endtime'])?$_POST['endtime']:showmsg('请填写结束时间!',1,$link);$setsqlarr['school']=trim($_POST['school'])?$_POST['school']:showmsg('请填写学校名称!',1,$link);$setsqlarr['speciality']=trim($_POST['speciality'])?$_POST['speciality']:showmsg('请填写专业名称!',1,$link);$setsqlarr['education']=trim($_POST['education'])?$_POST['education']:showmsg('请选择获得学历!',1,$link);$setsqlarr['education_cn']=trim($_POST['education_cn'])?$_POST['education_cn']:showmsg('请选择获得学历!',1,$link); //看到这里有个插入表“qs_resume_education”的操作,将教育背景相关的字段入库 if (inserttable(table('resume_education'),$setsqlarr)) { check_resume($_SESSION['uid'],intval($_REQUEST['pid']));
2.这里看到insert入库了,可以尝试加个单引号,入库后就会消除转义字符。我们先继续跟进inserttables后的check_resume函数
//检查简历的完成程度function check_resume($uid,$pid){global $db,$timestamp,$_CFG;$uid=intval($uid);$pid=intval($pid);$percent=0;$resume_basic=get_resume_basic($uid,$pid);$resume_intention=$resume_basic['intention_jobs'];$resume_specialty=$resume_basic['specialty'];//获取教育经历,出数据库了$resume_education=get_resume_education($uid,$pid);if (!empty($resume_basic))$percent=$percent+15;if (!empty($resume_intention))$percent=$percent+15;if (!empty($resume_specialty))$percent=$percent+15;if (!empty($resume_education))$percent=$percent+15;if ($resume_basic['photo_img'] && $resume_basic['photo_audit']=="1" && $resume_basic['photo_display']=="1"){$setsqlarr['photo']=1;}else{$setsqlarr['photo']=0;}if ($percent<60){ $setsqlarr['complete_percent']=$percent; $setsqlarr['complete']=2;}else{ $resume_work=get_resume_work($uid,$pid); $resume_training=get_resume_training($uid,$pid); $resume_photo=$resume_basic['photo_img']; if (!empty($resume_work))$percent=$percent+13; if (!empty($resume_training))$percent=$percent+13; if (!empty($resume_photo))$percent=$percent+14; $setsqlarr['complete']=1; $setsqlarr['complete_percent']=$percent; require_once(QISHI_ROOT_PATH.'include/splitword.class.php'); $sp = new SPWord(); $setsqlarr['key']=$resume_basic['intention_jobs'].$resume_basic['recentjobs'].$resume_basic['specialty']; $setsqlarr['key']="{$resume_basic['fullname']} ".$sp->extracttag($setsqlarr['key']); $setsqlarr['key']=str_replace(","," ",$resume_basic['intention_jobs'])." {$setsqlarr['key']} {$resume_basic['education_cn']}"; $setsqlarr['key']=$sp->pad($setsqlarr['key']); if (!empty($resume_education)) { //遍历教育经历所有字段,加入到数组里 foreach($resume_education as $li) { $setsqlarr['key']="{$li['school']} {$setsqlarr['key']} {$li['speciality']}"; } } $setsqlarr['refreshtime']=$timestamp;}//这里对教育经历做了次更新操作,二次注入由此产生!updatetable(table('resume'),$setsqlarr,"uid='{$uid}' AND id='{$pid}'");updatetable(table('resume_tmp'),$setsqlarr,"uid='{$uid}' AND id='{$pid}'");
3.我们填写一份简历简单试验下,在教育经历处学校名称字段填写aa’
保存后发现报错语句:
0x04 漏洞证明
构造获取数据库用户相关信息的POC:
查看简历发现简历姓名变成了root@localhost:
查看sql语句发现更新语句是成功执行的:
最后,有兴趣的同学可以继续获取其它的管理员账户等相关字段的信息。
本文由HackBraid整理总结,如需转载请联系作者。

Reasons for PHPSession failure include configuration errors, cookie issues, and session expiration. 1. Configuration error: Check and set the correct session.save_path. 2.Cookie problem: Make sure the cookie is set correctly. 3.Session expires: Adjust session.gc_maxlifetime value to extend session time.

Methods to debug session problems in PHP include: 1. Check whether the session is started correctly; 2. Verify the delivery of the session ID; 3. Check the storage and reading of session data; 4. Check the server configuration. By outputting session ID and data, viewing session file content, etc., you can effectively diagnose and solve session-related problems.

Multiple calls to session_start() will result in warning messages and possible data overwrites. 1) PHP will issue a warning, prompting that the session has been started. 2) It may cause unexpected overwriting of session data. 3) Use session_status() to check the session status to avoid repeated calls.

Configuring the session lifecycle in PHP can be achieved by setting session.gc_maxlifetime and session.cookie_lifetime. 1) session.gc_maxlifetime controls the survival time of server-side session data, 2) session.cookie_lifetime controls the life cycle of client cookies. When set to 0, the cookie expires when the browser is closed.

The main advantages of using database storage sessions include persistence, scalability, and security. 1. Persistence: Even if the server restarts, the session data can remain unchanged. 2. Scalability: Applicable to distributed systems, ensuring that session data is synchronized between multiple servers. 3. Security: The database provides encrypted storage to protect sensitive information.

Implementing custom session processing in PHP can be done by implementing the SessionHandlerInterface interface. The specific steps include: 1) Creating a class that implements SessionHandlerInterface, such as CustomSessionHandler; 2) Rewriting methods in the interface (such as open, close, read, write, destroy, gc) to define the life cycle and storage method of session data; 3) Register a custom session processor in a PHP script and start the session. This allows data to be stored in media such as MySQL and Redis to improve performance, security and scalability.

SessionID is a mechanism used in web applications to track user session status. 1. It is a randomly generated string used to maintain user's identity information during multiple interactions between the user and the server. 2. The server generates and sends it to the client through cookies or URL parameters to help identify and associate these requests in multiple requests of the user. 3. Generation usually uses random algorithms to ensure uniqueness and unpredictability. 4. In actual development, in-memory databases such as Redis can be used to store session data to improve performance and security.

Managing sessions in stateless environments such as APIs can be achieved by using JWT or cookies. 1. JWT is suitable for statelessness and scalability, but it is large in size when it comes to big data. 2.Cookies are more traditional and easy to implement, but they need to be configured with caution to ensure security.


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