source: https://www.securityfocus.com/bid/56109/info

BSW Gallery is prone to a vulnerability that lets attackers upload arbitrary files. The issue occurs because the application fails to adequately sanitize user-supplied input.

An attacker can exploit this vulnerability to upload arbitrary code and run it in the context of the web server process. This may facilitate unauthorized access or privilege escalation; other attacks are also possible. 

Code in uploadpic.php

print "<form method=\"POST\" action=\"dopic.php\"enctype=\"multipart/form-data\" style=\"width: 227px\">";
print "<table align=\"center\" style=\"width: 600px\"dir=\"ltr\"><tr><th align=\"right\"width=\"120\" class=\"topic\"><b>File Upload:</b></th>";
print "<th align=\"left\"><input type=\"file\" name=\"fileupload\"></th></tr>";
print "<tr><th><input type=\"hidden\" name=\"MAX_FILE_SIZE\" value=\"10240000\"></th></tr></table>";
print"<table align=\"center\"width=\"600\"dir=\"ltr\">";
print"<th class=\"topic\"width=\"120\"align=\"right\">Image Title</th><th align=\"left\"><input style=\"width:400\"type=\"text\" name=\"picture\" /></th></table>";
print"<table align=\"center\"dir=\"ltr\" width=\"600\"><th class=\"topic\" width=\"120\"align=\"right\">Image Description</th>";
print"<th align=\"left\"><textarea name=\"descrip\"cols=\"48\"rows=\"5\">&lt;/textarea&gt;</th></table>";

   Code in dopic.php

$fname=$_POST['picture'];
$descrip=$_POST['descrip'];
$file_dir ="gallery/";


foreach($_FILES as $file_name => $file_array) {
  echo "path: ".$file_array["tmp_name"]."<br/>\n";
  echo "name: ".$file_array["name"]."<br/>\n";
  echo "type: ".$file_array["type"]."<br/>\n";
  
  echo "size: ".$file_array["size"]."<br/>\n";

  if (is_uploaded_file($file_array["tmp_name"])) {
    move_uploaded_file($file_array["tmp_name"], "$file_dir/".$file_array["name"]) or die ("Couldn't copy");
    echo "Done!<br/>";
  }
   
}
$image=$file_dir.$file_array["name"];
$ip = getenv("REMOTE_ADDR");
$sql = "insert into gallery (picture,files,descrip,updated)values('$fname','$image','$descrip',now());";
mysql_query($sql,$mysql);
mysql_close($mysql);

------------------------------------------------------------------------------------
 Proof of Concept  :                                                                                                                              
 http://www.example.com/path_gallery/uploadpic.php                                                                                                         
 Shell :                                                                            
                                                                                    
 http://www.example.com/path_gallery/gallery/shell.php                                          
                                                                                    
 See for the demo :                                                                 
                                                                                    
 http://www.example.com/demo/demo1.png                                                    
 http://www.example.com/demo/demo2.png                                                    
 http://www.example.com/demo/demo3.png