이전 레벨과 소스코드는 거의 비슷하다고 합니다.
대신 쿠키를 확인해보면
num-id 형식을 hex로 인코딩 한 값이 들어갑니다.
스크립트 돌려줍시다.
| [Natas] Level18 (0) | 2016.10.24 |
|---|---|
| [Natas] Level17 (0) | 2016.10.23 |
| [Natas] Level16 (0) | 2016.10.23 |
| [Natas] Level15 (0) | 2016.10.23 |
| [Natas] Level14 (0) | 2016.10.23 |
<html> <head> <!-- This stuff in the header has nothing to do with the level --> <link rel="stylesheet" type="text/css" href="http://natas.labs.overthewire.org/css/level.css"> <link rel="stylesheet" href="http://natas.labs.overthewire.org/css/jquery-ui.css" /> <link rel="stylesheet" href="http://natas.labs.overthewire.org/css/wechall.css" /> <script src="http://natas.labs.overthewire.org/js/jquery-1.9.1.js"></script> <script src="http://natas.labs.overthewire.org/js/jquery-ui.js"></script> <script src=http://natas.labs.overthewire.org/js/wechall-data.js></script><script src="http://natas.labs.overthewire.org/js/wechall.js"></script> <script>var wechallinfo = { "level": "natas18", "pass": "<censored>" };</script></head> <body> <h1>natas18</h1> <div id="content"> <? $maxid = 640; // 640 should be enough for everyone function isValidAdminLogin() { /* {{{ */ if($_REQUEST["username"] == "admin") { /* This method of authentication appears to be unsafe and has been disabled for now. */ //return 1; } return 0; } /* }}} */ function isValidID($id) { /* {{{ */ return is_numeric($id); } /* }}} */ function createID($user) { /* {{{ */ global $maxid; return rand(1, $maxid); } /* }}} */ function debug($msg) { /* {{{ */ if(array_key_exists("debug", $_GET)) { print "DEBUG: $msg<br>"; } } /* }}} */ function my_session_start() { /* {{{ */ if(array_key_exists("PHPSESSID", $_COOKIE) and isValidID($_COOKIE["PHPSESSID"])) { if(!session_start()) { debug("Session start failed"); return false; } else { debug("Session start ok"); if(!array_key_exists("admin", $_SESSION)) { debug("Session was old: admin flag set"); $_SESSION["admin"] = 0; // backwards compatible, secure } return true; } } return false; } /* }}} */ function print_credentials() { /* {{{ */ if($_SESSION and array_key_exists("admin", $_SESSION) and $_SESSION["admin"] == 1) { print "You are an admin. The credentials for the next level are:<br>"; print "<pre>Username: natas19\n"; print "Password: <censored></pre>"; } else { print "You are logged in as a regular user. Login as an admin to retrieve credentials for natas19."; } } /* }}} */ $showform = true; if(my_session_start()) { print_credentials(); $showform = false; } else { if(array_key_exists("username", $_REQUEST) && array_key_exists("password", $_REQUEST)) { session_id(createID($_REQUEST["username"])); session_start(); $_SESSION["admin"] = isValidAdminLogin(); debug("New session started"); $showform = false; print_credentials(); } } if($showform) { ?> <p> Please login with your admin account to retrieve credentials for natas19. </p> <form action="index.php" method="POST"> Username: <input name="username"><br> Password: <input name="password"><br> <input type="submit" value="Login" /> </form> <? } ?> <div id="viewsource"><a href="index-source.html">View sourcecode</a></div> </div> </body> </html>
소스를 보면 admin 세션의 값이 1이 되어야만 패스워드를 뱉어낸다는 것을 알 수 있습니다.
하지만 일반적인 로그인으로는 return 값이 없기 때문에 1이 될 수 없겠죠.
여기서 admin이 로그인 되어 있어 세션 값이 1인 세션이 존재할 경우, 그 세션만 탈취하여 적용시킨다면 패스워드를 알아낼 수 있습니다.
간단하게 스크립트를 짜서 돌려줍시다. Key 부분은 파싱을 잘못 해서 출력이 안됐네요.
| [Natas] Level19 (0) | 2016.10.24 |
|---|---|
| [Natas] Level17 (0) | 2016.10.23 |
| [Natas] Level16 (0) | 2016.10.23 |
| [Natas] Level15 (0) | 2016.10.23 |
| [Natas] Level14 (0) | 2016.10.23 |
<html> <head> <!-- This stuff in the header has nothing to do with the level --> <link rel="stylesheet" type="text/css" href="http://natas.labs.overthewire.org/css/level.css"> <link rel="stylesheet" href="http://natas.labs.overthewire.org/css/jquery-ui.css" /> <link rel="stylesheet" href="http://natas.labs.overthewire.org/css/wechall.css" /> <script src="http://natas.labs.overthewire.org/js/jquery-1.9.1.js"></script> <script src="http://natas.labs.overthewire.org/js/jquery-ui.js"></script> <script src=http://natas.labs.overthewire.org/js/wechall-data.js></script><script src="http://natas.labs.overthewire.org/js/wechall.js"></script> <script>var wechallinfo = { "level": "natas17", "pass": "<censored>" };</script></head> <body> <h1>natas17</h1> <div id="content"> <? /* CREATE TABLE `users` ( `username` varchar(64) DEFAULT NULL, `password` varchar(64) DEFAULT NULL ); */ if(array_key_exists("username", $_REQUEST)) { $link = mysql_connect('localhost', 'natas17', '<censored>'); mysql_select_db('natas17', $link); $query = "SELECT * from users where username=\"".$_REQUEST["username"]."\""; if(array_key_exists("debug", $_GET)) { echo "Executing query: $query<br>"; } $res = mysql_query($query, $link); if($res) { if(mysql_num_rows($res) > 0) { //echo "This user exists.<br>"; } else { //echo "This user doesn't exist.<br>"; } } else { //echo "Error in query.<br>"; } mysql_close($link); } else { ?> <form action="index.php" method="POST"> Username: <input name="username"><br> <input type="submit" value="Check existence" /> </form> <? } ?> <div id="viewsource"><a href="index-source.html">View sourcecode</a></div> </div> </body> </html>
이번 소스를 보니 이전에 풀었던 Blind SQLi네요.
그런데 다른 점이 하나 있다면 참/거짓을 판별해주는 echo문이 주석 처리 됬다는 점입니다.
따라서 response 값의 차이로는 판별하기 힘들 것 같으니 time based blind SQLi로 풀면 될 것 같습니다.
중간에 타임 꼬여서 한번 더돌림..
| [Natas] Level19 (0) | 2016.10.24 |
|---|---|
| [Natas] Level18 (0) | 2016.10.24 |
| [Natas] Level16 (0) | 2016.10.23 |
| [Natas] Level15 (0) | 2016.10.23 |
| [Natas] Level14 (0) | 2016.10.23 |
<html> <head> <!-- This stuff in the header has nothing to do with the level --> <link rel="stylesheet" type="text/css" href="http://natas.labs.overthewire.org/css/level.css"> <link rel="stylesheet" href="http://natas.labs.overthewire.org/css/jquery-ui.css" /> <link rel="stylesheet" href="http://natas.labs.overthewire.org/css/wechall.css" /> <script src="http://natas.labs.overthewire.org/js/jquery-1.9.1.js"></script> <script src="http://natas.labs.overthewire.org/js/jquery-ui.js"></script> <script src=http://natas.labs.overthewire.org/js/wechall-data.js></script><script src="http://natas.labs.overthewire.org/js/wechall.js"></script> <script>var wechallinfo = { "level": "natas16", "pass": "<censored>" };</script></head> <body> <h1>natas16</h1> <div id="content"> For security reasons, we now filter even more on certain characters<br/><br/> <form> Find words containing: <input name=needle><input type=submit name=submit value=Search><br><br> </form> Output: <pre> <? $key = ""; if(array_key_exists("needle", $_REQUEST)) { $key = $_REQUEST["needle"]; } if($key != "") { if(preg_match('/[;|&`\'"]/',$key)) { print "Input contains an illegal character!"; } else { passthru("grep -i \"$key\" dictionary.txt"); } } ?> </pre> <div id="viewsource"><a href="index-source.html">View sourcecode</a></div> </div> </body> </html>
소스를 보니 이전에 했던 정규표현식 문제와 비슷합니다.
그러나 이번에는 key 부분에 double quotation으로 묶여있다는 점과 필터링이 강화되었다는 차이가 있네요.
여기서 생각 할 수 있는 것은 dictionary.txt를 무조건 참조할수밖에 없다는 것인데, 정규표현식에서는 if와 같이 조건을 걸어 줄 수 있습니다.
따라서 이를 이용하여 blind SQLi와 비스무리한 기법으로 패스워드를 찾아낼 수 있습니다.
| [Natas] Level18 (0) | 2016.10.24 |
|---|---|
| [Natas] Level17 (0) | 2016.10.23 |
| [Natas] Level15 (0) | 2016.10.23 |
| [Natas] Level14 (0) | 2016.10.23 |
| [Natas] Level13 (0) | 2016.10.23 |
<html> <head> <!-- This stuff in the header has nothing to do with the level --> <link rel="stylesheet" type="text/css" href="http://natas.labs.overthewire.org/css/level.css"> <link rel="stylesheet" href="http://natas.labs.overthewire.org/css/jquery-ui.css" /> <link rel="stylesheet" href="http://natas.labs.overthewire.org/css/wechall.css" /> <script src="http://natas.labs.overthewire.org/js/jquery-1.9.1.js"></script> <script src="http://natas.labs.overthewire.org/js/jquery-ui.js"></script> <script src=http://natas.labs.overthewire.org/js/wechall-data.js></script><script src="http://natas.labs.overthewire.org/js/wechall.js"></script> <script>var wechallinfo = { "level": "natas15", "pass": "<censored>" };</script></head> <body> <h1>natas15</h1> <div id="content"> <? /* CREATE TABLE `users` ( `username` varchar(64) DEFAULT NULL, `password` varchar(64) DEFAULT NULL ); */ if(array_key_exists("username", $_REQUEST)) { $link = mysql_connect('localhost', 'natas15', '<censored>'); mysql_select_db('natas15', $link); $query = "SELECT * from users where username=\"".$_REQUEST["username"]."\""; if(array_key_exists("debug", $_GET)) { echo "Executing query: $query<br>"; } $res = mysql_query($query, $link); if($res) { if(mysql_num_rows($res) > 0) { echo "This user exists.<br>"; } else { echo "This user doesn't exist.<br>"; } } else { echo "Error in query.<br>"; } mysql_close($link); } else { ?> <form action="index.php" method="POST"> Username: <input name="username"><br> <input type="submit" value="Check existence" /> </form> <? } ?> <div id="viewsource"><a href="index-source.html">View sourcecode</a></div> </div> </body> </html>
Blind SQLi인것 같습니다.
그래서 돌렸습니다.
| [Natas] Level17 (0) | 2016.10.23 |
|---|---|
| [Natas] Level16 (0) | 2016.10.23 |
| [Natas] Level14 (0) | 2016.10.23 |
| [Natas] Level13 (0) | 2016.10.23 |
| [Natas] Level12 (0) | 2016.10.23 |
로그인 폼이 있는 것을 보니 SQLi네요.
<html> <head> <!-- This stuff in the header has nothing to do with the level --> <link rel="stylesheet" type="text/css" href="http://natas.labs.overthewire.org/css/level.css"> <link rel="stylesheet" href="http://natas.labs.overthewire.org/css/jquery-ui.css" /> <link rel="stylesheet" href="http://natas.labs.overthewire.org/css/wechall.css" /> <script src="http://natas.labs.overthewire.org/js/jquery-1.9.1.js"></script> <script src="http://natas.labs.overthewire.org/js/jquery-ui.js"></script> <script src=http://natas.labs.overthewire.org/js/wechall-data.js></script><script src="http://natas.labs.overthewire.org/js/wechall.js"></script> <script>var wechallinfo = { "level": "natas14", "pass": "<censored>" };</script></head> <body> <h1>natas14</h1> <div id="content"> <? if(array_key_exists("username", $_REQUEST)) { $link = mysql_connect('localhost', 'natas14', '<censored>'); mysql_select_db('natas14', $link); $query = "SELECT * from users where username=\"".$_REQUEST["username"]."\" and password=\"".$_REQUEST["password"]."\""; if(array_key_exists("debug", $_GET)) { echo "Executing query: $query<br>"; } if(mysql_num_rows(mysql_query($query, $link)) > 0) { echo "Successful login! The password for natas15 is <censored><br>"; } else { echo "Access denied!<br>"; } mysql_close($link); } else { ?> <form action="index.php" method="POST"> Username: <input name="username"><br> Password: <input name="password"><br> <input type="submit" value="Login" /> </form> <? } ?> <div id="viewsource"><a href="index-source.html">View sourcecode</a></div> </div> </body> </html>
$query 부분이 취약해보입니다.
조져줍시다.
| [Natas] Level16 (0) | 2016.10.23 |
|---|---|
| [Natas] Level15 (0) | 2016.10.23 |
| [Natas] Level13 (0) | 2016.10.23 |
| [Natas] Level12 (0) | 2016.10.23 |
| [Natas] Level11 (0) | 2016.10.22 |
<html> <head> <!-- This stuff in the header has nothing to do with the level --> <link rel="stylesheet" type="text/css" href="http://natas.labs.overthewire.org/css/level.css"> <link rel="stylesheet" href="http://natas.labs.overthewire.org/css/jquery-ui.css" /> <link rel="stylesheet" href="http://natas.labs.overthewire.org/css/wechall.css" /> <script src="http://natas.labs.overthewire.org/js/jquery-1.9.1.js"></script> <script src="http://natas.labs.overthewire.org/js/jquery-ui.js"></script> <script src=http://natas.labs.overthewire.org/js/wechall-data.js></script><script src="http://natas.labs.overthewire.org/js/wechall.js"></script> <script>var wechallinfo = { "level": "natas13", "pass": "<censored>" };</script></head> <body> <h1>natas13</h1> <div id="content"> For security reasons, we now only accept image files!<br/><br/> <? function genRandomString() { $length = 10; $characters = "0123456789abcdefghijklmnopqrstuvwxyz"; $string = ""; for ($p = 0; $p < $length; $p++) { $string .= $characters[mt_rand(0, strlen($characters)-1)]; } return $string; } function makeRandomPath($dir, $ext) { do { $path = $dir."/".genRandomString().".".$ext; } while(file_exists($path)); return $path; } function makeRandomPathFromFilename($dir, $fn) { $ext = pathinfo($fn, PATHINFO_EXTENSION); return makeRandomPath($dir, $ext); } if(array_key_exists("filename", $_POST)) { $target_path = makeRandomPathFromFilename("upload", $_POST["filename"]); if(filesize($_FILES['uploadedfile']['tmp_name']) > 1000) { echo "File is too big"; } else if (! exif_imagetype($_FILES['uploadedfile']['tmp_name'])) { echo "File is not an image"; } else { if(move_uploaded_file($_FILES['uploadedfile']['tmp_name'], $target_path)) { echo "The file <a href=\"$target_path\">$target_path</a> has been uploaded"; } else{ echo "There was an error uploading the file, please try again!"; } } } else { ?> <form enctype="multipart/form-data" action="index.php" method="POST"> <input type="hidden" name="MAX_FILE_SIZE" value="1000" /> <input type="hidden" name="filename" value="<? print genRandomString(); ?>.jpg" /> Choose a JPEG to upload (max 1KB):<br/> <input name="uploadedfile" type="file" /><br /> <input type="submit" value="Upload File" /> </form> <? } ?> <div id="viewsource"><a href="index-source.html">View sourcecode</a></div>
이번에는 exif_imagetype으로 이미지 파일인지 검증하는 함수를 추가해줬네요.
간단하게 헤더 추가해줍시다.
| [Natas] Level15 (0) | 2016.10.23 |
|---|---|
| [Natas] Level14 (0) | 2016.10.23 |
| [Natas] Level12 (0) | 2016.10.23 |
| [Natas] Level11 (0) | 2016.10.22 |
| [Natas] Level10 (0) | 2016.10.22 |
