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Room / Challenge: QnQSec Portal (Web) Metadata Author: jameskaois CTF: QnQSec CTF 2025 Challenge: QnQSec Portal (web) Target / URL: http://161.97.155.116:5001/ Points: 50 Date: 20-10-2025 Goal We have to get the flag by get access as admin. My Solution First we have to examine the app.py. There are some noticable routes: /login route: @app.route('/login', methods=['GET', 'POST']) def login(): if request.method == 'GET': return render_template('login.html') username = (request.form.get('username') or '').strip() password = request.form.get('password') or '' if not username or not password: flash('Missing username or password', 'error') return render_template('login.html') db = get_db() row = db.execute( 'select username, password from users where username = lower(?) and password = ?', (username, md5(password.encode()).hexdigest()) ).fetchone() if row: session['user'] = username.title() role = "admin" if username.lower() == "flag" else "user" token = generate_jwt(session['user'],role,app.config['JWT_EXPIRES_MIN'],app.config['JWT_SECRET']) resp = make_response(redirect(url_for('account'))) resp.set_cookie("admin_jwt", token, httponly=False, samesite="Lax") return resp flash('Invalid username or password', 'error') return render_template('login.html') /account route: ...

Room / Challenge: A Easy Web (Web) Metadata Author: jameskaois CTF: QnQSec CTF 2025 Challenge: A Easy Web (web) Target / URL: http://161.97.155.116:5000/ Points: 50 Date: 20-10-2025 Goal We have to get the flag by guessing the UID to gain access as admin. My Solution This is an easy challenge however we need to do some guessing and hope for luck. The description of the challenge is: This is the web I mad for testing but I don’t know if there anything strange can you help me figure out? We need to find something strange in the website to leverage it and gain access as admin. Let’s visit the page: ...

Description Vulnerability: XSS (Stored) Impact: Leveraging XSS Scripting to get our desired data. LOW Security Level if( isset( $_POST[ 'btnSign' ] ) ) { // Get input $message = trim( $_POST[ 'mtxMessage' ] ); $name = trim( $_POST[ 'txtName' ] ); // Sanitize message input $message = stripslashes( $message ); $message = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $message ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); // Sanitize name input $name = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $name ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); // Update database $query = "INSERT INTO guestbook ( comment, name ) VALUES ( '$message', '$name' );"; $result = mysqli_query($GLOBALS["___mysqli_ston"], $query ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' ); //mysql_close(); } The app just INSERT the records to database with no checks ...

Description Vulnerability: XSS (Reflected) Impact: Leveraging XSS Scripting to get our desired data. LOW Security Level The source code doesn’t have any check: header ("X-XSS-Protection: 0"); // Is there any input? if( array_key_exists( "name", $_GET ) && $_GET[ 'name' ] != NULL ) { // Feedback for end user echo '<pre>Hello ' . $_GET[ 'name' ] . '</pre>'; } So similar to XSS (DOM) we can use simple payload <script>alert(document.cookie)</script> MEDIUM Security Level This source code has new check on <script>: header ("X-XSS-Protection: 0"); // Is there any input? if( array_key_exists( "name", $_GET ) && $_GET[ 'name' ] != NULL ) { // Get input $name = str_replace( '<script>', '', $_GET[ 'name' ] ); // Feedback for end user echo "<pre>Hello {$name}</pre>"; } So we can use the img trick: <img src=x onerror=alert(document.cookie)> ...

Description Vulnerability: XSS (DOM) Impact: Leveraging XSS Scripting to get our desired data. LOW Security Level This source code doesn’t have any checks: <?php # No protections, anything goes ?> And the choosing language functionality take the value and add them to the query param default on the URL: /vulnerabilities/xss_d/?default=<value>, the web app with take the <value> render them to the first option element: You can try type a Javascript code to get cookie of the browser: ?default=<script>alert(document.cookie)</script> ...

Description Vulnerability: Weak Session IDs Impact: Session IDs may be guessed to gain access as other accounts. LOW Security Level This level has really simple code: <?php $html = ""; if ($_SERVER['REQUEST_METHOD'] == "POST") { if (!isset ($_SESSION['last_session_id'])) { $_SESSION['last_session_id'] = 0; } $_SESSION['last_session_id']++; $cookie_value = $_SESSION['last_session_id']; setcookie("dvwaSession", $cookie_value); } ?> The dvwaSession cookie will simply increases 1 when we click the Generate button. MEDIUM Security Level This MEDIUM Security Level is also simple it take time() value which is the current Unix timestamp and set that to dvwaSession cookie value: ...

Description Vulnerability: SQL Injection Impact: Using vulnerability in SQL queries to get access to restricted data. LOW Security Level The source code doesn’t have any check on the input id it just pass the value to the query. We can easily use this payload to get tables list: ' UNION SELECT user, password FROM users # Source code doesn’t check anything: $query = "SELECT first_name, last_name FROM users WHERE user_id = '$id';"; Result: ...

Description Vulnerability: SQL Blind Injection Impact: Levaraging SQL Blind Injection to get the data that we aren’t supposed to know. LOW Security Level The SQL Blind Injection is basically harder for us to retreive our desired data when comparing to normal SQL Injection. You can see this code from the source: $exists = false; if ($result !== false) { try { $exists = (mysqli_num_rows( $result ) > 0); } catch(Exception $e) { $exists = false; } } And whatever we give id param it just have 2 results: ...

Description Vulnerability: Open HTTP Redirect Impact: Taking advantage of redirects to trick users go to other websites. LOW Security Level The source code in vulnerabilities/open_redirect/source/low.php is: if (array_key_exists ("redirect", $_GET) && $_GET['redirect'] != "") { header ("location: " . $_GET['redirect']); exit; } http_response_code (500); ?> <p>Missing redirect target.</p> <?php exit; No checks so we can leverage this if you check the url of Quote 1 and Quote 2 it is: source/low.php?redirect=info.php?id=1, so we can use this redirect query param to redirect users to whatever page we want: ...

Description Vulnerability: Javascript Attacks Impact: Attack to Javascript code to achieve our goals. LOW Security Level This is the source code of the server: $page[ 'body' ] .= <<<EOF <script> /* MD5 code from here https://github.com/blueimp/JavaScript-MD5 */ !function(n){"use strict";function t(n,t){var r=(65535&n)+(65535&t);return(n>>16)+(t>>16)+(r>>16)<<16|65535&r}function r(n,t){return n<<t|n>>>32-t}function e(n,e,o,u,c,f){return t(r(t(t(e,n),t(u,f)),c),o)}function o(n,t,r,o,u,c,f){return e(t&r|~t&o,n,t,u,c,f)}function u(n,t,r,o,u,c,f){return e(t&o|r&~o,n,t,u,c,f)}function c(n,t,r,o,u,c,f){return e(t^r^o,n,t,u,c,f)}function f(n,t,r,o,u,c,f){return e(r^(t|~o),n,t,u,c,f)}function i(n,r){n[r>>5]|=128<<r%32,n[14+(r+64>>>9<<4)]=r;var e,i,a,d,h,l=1732584193,g=-271733879,v=-1732584194,m=271733878;for(e=0;e<n.length;e+=16)i=l,a=g,d=v,h=m,g=f(g=f(g=f(g=f(g=c(g=c(g=c(g=c(g=u(g=u(g=u(g=u(g=o(g=o(g=o(g=o(g,v=o(v,m=o(m,l=o(l,g,v,m,n[e],7,-680876936),g,v,n[e+1],12,-389564586),l,g,n[e+2],17,606105819),m,l,n[e+3],22,-1044525330),v=o(v,m=o(m,l=o(l,g,v,m,n[e+4],7,-176418897),g,v,n[e+5],12,1200080426),l,g,n[e+6],17,-1473231341),m,l,n[e+7],22,-45705983),v=o(v,m=o(m,l=o(l,g,v,m,n[e+8],7,1770035416),g,v,n[e+9],12,-1958414417),l,g,n[e+10],17,-42063),m,l,n[e+11],22,-1990404162),v=o(v,m=o(m,l=o(l,g,v,m,n[e+12],7,1804603682),g,v,n[e+13],12,-40341101),l,g,n[e+14],17,-1502002290),m,l,n[e+15],22,1236535329),v=u(v,m=u(m,l=u(l,g,v,m,n[e+1],5,-165796510),g,v,n[e+6],9,-1069501632),l,g,n[e+11],14,643717713),m,l,n[e],20,-373897302),v=u(v,m=u(m,l=u(l,g,v,m,n[e+5],5,-701558691),g,v,n[e+10],9,38016083),l,g,n[e+15],14,-660478335),m,l,n[e+4],20,-405537848),v=u(v,m=u(m,l=u(l,g,v,m,n[e+9],5,568446438),g,v,n[e+14],9,-1019803690),l,g,n[e+3],14,-187363961),m,l,n[e+8],20,1163531501),v=u(v,m=u(m,l=u(l,g,v,m,n[e+13],5,-1444681467),g,v,n[e+2],9,-51403784),l,g,n[e+7],14,1735328473),m,l,n[e+12],20,-1926607734),v=c(v,m=c(m,l=c(l,g,v,m,n[e+5],4,-378558),g,v,n[e+8],11,-2022574463),l,g,n[e+11],16,1839030562),m,l,n[e+14],23,-35309556),v=c(v,m=c(m,l=c(l,g,v,m,n[e+1],4,-1530992060),g,v,n[e+4],11,1272893353),l,g,n[e+7],16,-155497632),m,l,n[e+10],23,-1094730640),v=c(v,m=c(m,l=c(l,g,v,m,n[e+13],4,681279174),g,v,n[e],11,-358537222),l,g,n[e+3],16,-722521979),m,l,n[e+6],23,76029189),v=c(v,m=c(m,l=c(l,g,v,m,n[e+9],4,-640364487),g,v,n[e+12],11,-421815835),l,g,n[e+15],16,530742520),m,l,n[e+2],23,-995338651),v=f(v,m=f(m,l=f(l,g,v,m,n[e],6,-198630844),g,v,n[e+7],10,1126891415),l,g,n[e+14],15,-1416354905),m,l,n[e+5],21,-57434055),v=f(v,m=f(m,l=f(l,g,v,m,n[e+12],6,1700485571),g,v,n[e+3],10,-1894986606),l,g,n[e+10],15,-1051523),m,l,n[e+1],21,-2054922799),v=f(v,m=f(m,l=f(l,g,v,m,n[e+8],6,1873313359),g,v,n[e+15],10,-30611744),l,g,n[e+6],15,-1560198380),m,l,n[e+13],21,1309151649),v=f(v,m=f(m,l=f(l,g,v,m,n[e+4],6,-145523070),g,v,n[e+11],10,-1120210379),l,g,n[e+2],15,718787259),m,l,n[e+9],21,-343485551),l=t(l,i),g=t(g,a),v=t(v,d),m=t(m,h);return[l,g,v,m]}function a(n){var t,r="",e=32*n.length;for(t=0;t<e;t+=8)r+=String.fromCharCode(n[t>>5]>>>t%32&255);return r}function d(n){var t,r=[];for(r[(n.length>>2)-1]=void 0,t=0;t<r.length;t+=1)r[t]=0;var e=8*n.length;for(t=0;t<e;t+=8)r[t>>5]|=(255&n.charCodeAt(t/8))<<t%32;return r}function h(n){return a(i(d(n),8*n.length))}function l(n,t){var r,e,o=d(n),u=[],c=[];for(u[15]=c[15]=void 0,o.length>16&&(o=i(o,8*n.length)),r=0;r<16;r+=1)u[r]=909522486^o[r],c[r]=1549556828^o[r];return e=i(u.concat(d(t)),512+8*t.length),a(i(c.concat(e),640))}function g(n){var t,r,e="";for(r=0;r<n.length;r+=1)t=n.charCodeAt(r),e+="0123456789abcdef".charAt(t>>>4&15)+"0123456789abcdef".charAt(15&t);return e}function v(n){return unescape(encodeURIComponent(n))}function m(n){return h(v(n))}function p(n){return g(m(n))}function s(n,t){return l(v(n),v(t))}function C(n,t){return g(s(n,t))}function A(n,t,r){return t?r?s(t,n):C(t,n):r?m(n):p(n)}"function"==typeof define&&define.amd?define(function(){return A}):"object"==typeof module&&module.exports?module.exports=A:n.md5=A}(this); function rot13(inp) { return inp.replace(/[a-zA-Z]/g,function(c){return String.fromCharCode((c<="Z"?90:122)>=(c=c.charCodeAt(0)+13)?c:c-26);}); } function generate_token() { var phrase = document.getElementById("phrase").value; document.getElementById("token").value = md5(rot13(phrase)); } generate_token(); </script> EOF; This code uses MD5 Encrypt and ROT13 to generate a token through generate_token function and it takes the value of element with phrase id, which is the phrase input in the UI. ...