### 简述
Dedecms是一款开源的PHP开源网站管理系统。
DeDecms(织梦CMS) V5.7.72 正式版20180109 (最新版)
前台会员模块是采用Cookie中的 DedeUserID+DedeUserID__ckMd5字段进行身份鉴别
DedeUserID用于定位区别用户，DedeUserID__ckMd5则是服务器生成散列，用于安全验证
Dedecms一处代码由于逻辑不够严谨，导致可以输入字符并获得服务器生成散列
劫持DedeUserID__ckMd5字段，绕过安全校验，配合类型转换造成任意用户登录漏洞
漏洞详细原理
文件位置:dedecms/member/index.php:110行
```
require_once(DEDEMEMBER . '/inc/config_space.php');
if ($action == '') {
include_once(DEDEINC . "/channelunit.func.php");
$dpl = new DedeTemplate();
$tplfile = DEDEMEMBER . "/space/{$_vars['spacestyle']}/index.htm";
//更新最近访客记录及站点统计记录
$vtime = time();
$last_vtime = GetCookie('last_vtime');
$last_vid = GetCookie('last_vid');
if (empty($last_vtime)) {
$last_vtime = 0;
}
if ($vtime - $last_vtime > 3600 || !preg_match('#,' . $uid . ',#i', ',' . $last_vid . ',')) {
if ($last_vid != '') {
$last_vids = explode(',', $last_vid);
$i = 0;
$last_vid = $uid;
foreach ($last_vids as $lsid) {
if ($i > 10) {
break;
} else if ($lsid != $uid) {
$i++;
$last_vid .= ',' . $last_vid;
}
}
} else {
$last_vid = $uid;
}
PutCookie('last_vtime', $vtime, 3600 * 24, '/');
PutCookie('last_vid', $last_vid, 3600 * 24, '/');
```
这段函数中$uid是我们可控的，如果Cookie中last_vid字段不存在就会走进这个分支
```
} else {
$last_vid = $uid;
}
```
也就变为`$last_vid`可控，然后`$last_vid`经过`PutCookie`函数进行处理
### 顺便一提
文件位置：dedecms/include/helpers/cookie.helper.php
PutCookie这个函数是Dedecms在setcookie时封装的函数
GetCookie这个函数是Dedecms在获取Cookie中值封装的函数
如果Set一个键值对，PutCookie会Set两对Cookie，一个是要SET的键值对
另一个是值和key进行md5的哈希再截取前十六位的安全校验字符串(键名为$key+'__ckMd5')
```
if ( ! function_exists('PutCookie'))
{
function PutCookie($key, $value, $kptime=0, $pa="/")
{
global $cfg_cookie_encode,$cfg_domain_cookie;
setcookie($key, $value, time()+$kptime, $pa,$cfg_domain_cookie);
setcookie($key.'__ckMd5', substr(md5($cfg_cookie_encode.$value),0,16), time()+$kptime, $pa,$cfg_domain_cookie);
}
}
```
GetCookie在返回键值之前，会通过PutCookie生成的十六位安全校验字符串对键值进行安全校验
确保获得的键值对有效且为服务器Set,增强安全性（但这里并不能抵御密文重放）
```
if ( ! function_exists('GetCookie'))
{
function GetCookie($key)
{
global $cfg_cookie_encode;
if( !isset($_COOKIE[$key]) || !isset($_COOKIE[$key.'__ckMd5']) )
{
return '';
}
else
{
if($_COOKIE[$key.'__ckMd5']!=substr(md5($cfg_cookie_encode.$_COOKIE[$key]),0,16))
{
return '';
}
else
{
return $_COOKIE[$key];
}
}
}
}
```
在`$last_vid`经过`PutCookie`函数进行处理后，我们已经在`Cookie`可以获得校验哈希，绕过安全校验
### Payload注入点
文件位置:dedecms/include/memberlogin.class.php:161行
```
function __construct($kptime = -1, $cache=FALSE)
{
global $dsql;
if($kptime==-1){
$this->M_KeepTime = 3600 * 24 * 7;
}else{
$this->M_KeepTime = $kptime;
}
$formcache = FALSE;
$this->M_ID = $this->GetNum(GetCookie("DedeUserID"));
$this->M_LoginTime = GetCookie("DedeLoginTime");
$this->fields = array();
$this->isAdmin = FALSE;
if(empty($this->M_ID))
{
$this->ResetUser();
}else{
$this->M_ID = intval($this->M_ID);
if ($cache)
{
$this->fields = GetCache($this->memberCache, $this->M_ID);
if( empty($this->fields) )
{
$this->fields = $dsql->GetOne("Select * From `#@__member` where mid='{$this->M_ID}' ");
} else {
$formcache = TRUE;
}
} else {
$this->fields = $dsql->GetOne("Select * From `#@__member` where mid='{$this->M_ID}' ");
}
if(is_array($this->fields)){
#api{{
if(defined('UC_API') && @include_once DEDEROOT.'/uc_client/client.php')
{
if($data = uc_get_user($this->fields['userid']))
{
if(uc_check_avatar($data[0]) && !strstr($this->fields['face'],UC_API))
{
$this->fields['face'] = UC_API.'/avatar.php?uid='.$data[0].'&size=middle';
$dsql->ExecuteNoneQuery("UPDATE `#@__member` SET `face`='".$this->fields['face']."' WHERE `mid`='{$this->M_ID}'");
}
}
}
#/aip}}
//间隔一小时更新一次用户登录时间
if(time() - $this->M_LoginTime > 3600)
{
$dsql->ExecuteNoneQuery("update `#@__member` set logintime='".time()."',loginip='".GetIP()."' where mid='".$this->fields['mid']."';");
PutCookie("DedeLoginTime",time(),$this->M_KeepTime);
}
$this->M_LoginID = $this->fields['userid'];
$this->M_MbType = $this->fields['mtype'];
$this->M_Money = $this->fields['money'];
$this->M_UserName = FormatUsername($this->fields['uname']);
$this->M_Scores = $this->fields['scores'];
$this->M_Face = $this->fields['face'];
$this->M_Rank = $this->fields['rank'];
$this->M_Spacesta = $this->fields['spacesta'];
$sql = "Select titles From #@__scores where integral<={$this->fields['scores']} order by integral desc";
$scrow = $dsql->GetOne($sql);
$this->fields['honor'] = $scrow['titles'];
$this->M_Honor = $this->fields['honor'];
if($this->fields['matt']==10) $this->isAdmin = TRUE;
$this->M_UpTime = $this->fields['uptime'];
$this->M_ExpTime = $this->fields['exptime'];
$this->M_JoinTime = MyDate('Y-m-d',$this->fields['jointime']);
if($this->M_Rank>10 && $this->M_UpTime>0){
$this->M_HasDay = $this->Judgemember();
}
if( !$formcache )
{
SetCache($this->memberCache, $this->M_ID, $this->fields, 1800);
}
}else{
$this->ResetUser();
}
}
}
```
我们注入0000001(注册账户的账户名)和对应的`__ckMd`5校验值
```
$this->M_ID = $this->GetNum(GetCookie("DedeUserID"));
```
这里必须注册名0000001为的账户，不然没法通过另一个校验页面（校验账户是否存在）
文件位置：dedecms/member/inc/config_space.php
```
if(!is_array($_vars))
{
ShowMsg("你访问的用户可能已经被删除！","javascript:;");
exit();
}
```
`$this->M_ID`赋值后变为0000001，然后巧妙地经过intval类型转换，变为1，也就是admin的id，也可以是任意用户的id
```
$this->M_ID = intval($this->M_ID);
```
然后带入了SQL查询语句，然后使用查询结果对登录信息进行赋值，造成任意用户登录。
```
else {
$this->fields = $dsql->GetOne("Select * From `#@__member` where mid='{$this->M_ID}' ");
}
if(is_array($this->fields)){
#api{{
if(defined('UC_API') && @include_once DEDEROOT.'/uc_client/client.php')
{
if($data = uc_get_user($this->fields['userid']))
{
if(uc_check_avatar($data[0]) && !strstr($this->fields['face'],UC_API))
{
$this->fields['face'] = UC_API.'/avatar.php?uid='.$data[0].'&size=middle';
$dsql->ExecuteNoneQuery("UPDATE `#@__member` SET `face`='".$this->fields['face']."' WHERE `mid`='{$this->M_ID}'");
}
}
}
#/aip}}
//间隔一小时更新一次用户登录时间
if(time() - $this->M_LoginTime > 3600)
{
$dsql->ExecuteNoneQuery("update `#@__member` set logintime='".time()."',loginip='".GetIP()."' where mid='".$this->fields['mid']."';");
PutCookie("DedeLoginTime",time(),$this->M_KeepTime);
}
$this->M_LoginID = $this->fields['userid'];
$this->M_MbType = $this->fields['mtype'];
$this->M_Money = $this->fields['money'];
$this->M_UserName = FormatUsername($this->fields['uname']);
$this->M_Scores = $this->fields['scores'];
$this->M_Face = $this->fields['face'];
$this->M_Rank = $this->fields['rank'];
$this->M_Spacesta = $this->fields['spacesta'];
$sql = "Select titles From #@__scores where integral<={$this->fields['scores']} order by integral desc";
$scrow = $dsql->GetOne($sql);
$this->fields['honor'] = $scrow['titles'];
$this->M_Honor = $this->fields['honor'];
if($this->fields['matt']==10) $this->isAdmin = TRUE;
$this->M_UpTime = $this->fields['uptime'];
$this->M_ExpTime = $this->fields['exptime'];
$this->M_JoinTime = MyDate('Y-m-d',$this->fields['jointime']);
```
### 漏洞演示
①注册0000001账户（用于登录admin,其他账户类推）
②注入Payload并获安全校验值
③
### 漏洞更深入(管理员密码重置)
①利用之前的老漏洞重置admin的密码，这时只重置了member表里面的admin密码
②利用现在这个漏洞登录admin,然后访问member/edit_baseinfo.php页面，member/edit_baseinfo.php中的修改信息的老密码判断是跟member表进行对比，刚好被我们上面步骤①重置了
③满足条件后，修改密码的时候会同时修改admin.member两张表的密码
文件位置:dedecms/member/edit_baseinfo.php:109行
```
if( !in_array($sex, array('男','女','保密')) )
{
ShowMsg('请选择正常的性别！','-1');
exit();
}
$query1 = "UPDATE `#@__member` SET pwd='$pwd',sex='$sex'{$addupquery} where mid='".$cfg_ml->M_ID."' ";
$dsql->ExecuteNoneQuery($query1);
//如果是管理员，修改其后台密码
if($cfg_ml->fields['matt']==10 && $pwd2!="")
{
$query2 = "UPDATE `#@__admin` SET pwd='$pwd2' where id='".$cfg_ml->M_ID."' ";
$dsql->ExecuteNoneQuery($query2);
}
// 清除会员缓存
$cfg_ml->DelCache($cfg_ml->M_ID);
ShowMsg('成功更新你的基本资料！','edit_baseinfo.php',0,5000);
exit();
```
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