Non-alphanumeric Backdoors

@$_[]=@!+_ apache_child_terminate assert base64_decode bzopen chgrp chmod chown copy create_function curl_exec curl_multi_exec edoced_46esab eval exec exif_imagetype exif_read_data exif_thumbnail extract fclose file file_exists file_get_contents file_put_contents fileatime filectime filegroup fileinode filemtime fileowner fileperms filesize filetype fopen fsockopen ftp_get ftp_nb_get ftp_nb_put ftp_put get_meta_tags getimagesize glob gzfile gzopen hash_file hash_hmac_file hash_update_file highlight_file image2wbmp imagecreatefromgif imagecreatefromjpeg imagecreatefrompng imagecreatefromwbmp imagecreatefromxbm imagecreatefromxpm imagegd imagegd2 imagegif imagejpeg imagepng imagewbmp imagexbm ini_set iptcembed is_dir is_executable is_file is_link is_readable is_uploaded_file is_writable is_writeable lchgrp lchown link linkinfo lstat mail md5_file mkdir move_uploaded_file parse_ini_file parse_str passthru pathinfo pcntl_exec pfsockopen php_strip_whitespace phpinfo popen posix_kill posix_mkfifo posix_setpgid posix_setsid posix_setuid preg_replace proc_close proc_nice proc_open proc_terminate putenv python_eval read_exif_data readfile readgzfile readlink realpath rename rmdir sha1_file shell_exec show_source stat str_replace symlink system tcpflood tempnam tmpfile touch udpflood unlink

These characters should trigger an alarm if caught by eye in a source file.