Php multi-base programming practices for detecting image Trojans

I have a tutorial on creating image Trojans, but I have not found any programs for detection. I analyzed this Trojan program from the production principle and wrote the following Upload classes to share with you, for more information about this, I applied to join an open-source organization. They asked me to write a function to check whether there is a Trojan script in the image.
In fact, I didn't know anything at first, but I checked some information on the internet and found all the tutorials for creating image Trojans. I didn't find any programs for detection.

After several thoughts, I decided to analyze this Trojan program from the production principle. This kind of Trojan program was written in hexadecimal code. I had the chance to write the following Upload class. Finally, the organization quiz was passed. Haha

Now I will share it with you. please correct me if there is anything bad! Anyon@139.com;
The code is as follows:
/**
+ ------------------------------------------------------------------------------
* Upload file Upload class
+ ------------------------------------------------------------------------------
* @ Package Upload
* @ Author Anyon
* @ Version $ Id: Upload. class. php 2013-3-20 21:47:23 Anyon $
+ ------------------------------------------------------------------------------
*/
Class Upload {
Private static $ image = null;
Private static $ status = 0;
Private static $ suffix = null;
Private static $ imageType = array('.jpg ', '.bmp', '.gif ', '.png ');
Private static $ message = array (
'0' => 'no error occurred. the file is uploaded successfully. ',
'1' => 'the uploaded file exceeds the limit of the upload_max_filesize option in php. ini. ',
'2' => 'the size of the uploaded file exceeds the value specified by the MAX_FILE_SIZE option in the HTML form. ',
'3' => 'only part of the file is uploaded. ',
'4' => 'no file is uploaded. ',
'5' => 'indicates the file that failed the security check. ',
'6' => 'cannot find the temporary folder. ',
'7' => 'file writing failed. ',
'8' => 'File type not supported ',
'9' => 'the temporary file to be uploaded is lost. ',
);
// @ Start file Upload
Public static function start ($ feild = 'file '){
If (! Empty ($ _ FILES )){
Self: $ status = $ _ FILES [$ feild] ['error'];
If (self: $ status> 0)
Return array ('status' => self: $ status, 'MSG '=> self: $ message [self: $ status]);
Self: $ image = $ _ FILES [$ feild] ['tmp _ name'];
Self: $ suffix = strtolower (strrchr ($ _ FILES [$ feild] ['name'], '.');
Return array ('status' => self: _ upload (), 'path' => self: $ image, 'MSG '=> self: $ message [self:: $ status]);
} Else {
Return array ('status' => self: $ status, 'MSG '=> self: $ message [self: $ status]);
}
}
// @ Start private Upload
Private static function _ upload ($ path = './upload /'){
Date_default_timezone_set ('prc ');
$ NewFile = $ path. date ('Y/m/d/His '). rand (100,999). self: $ suffix;
Self: umkdir (dirname ($ newFile ));
If (is_uploaded_file (self ::$ image) & move_uploaded_file (self ::$ image, $ newFile )){
Self: $ image = $ newFile;
If (in_array (self: $ suffix, self: $ imageType ))
Return self: checkHex ();
Else
Return self: $ status = 0;
} Else {
Return self: $ status = 9;
}
}
// @ Private hexadecimal check
Private static function checkHex (){
If (file_exists (self: $ image )){
$ Resource = fopen (self: $ image, 'RB ');
$ FileSize = filesize (self: $ image );
Fseek ($ resource, 0 );
If ($ fileSize> 512) {// Get the header and tail
$ HexCode = bin2hex (fread ($ resource, 512 ));
Fseek ($ resource, $ fileSize-512 );
$ HexCode. = bin2hex (fread ($ resource, 512 ));
} Else {// retrieve all
$ HexCode = bin2hex (fread ($ resource, $ fileSize ));
}
Fclose ($ resource );
/* Match <% () %> */
/* Match in hexadecimal notation */
/* Match in hexadecimal notation