How can i check upload file for virus before store it?
I previously read this topic,but how can i do it programmatic and return result for user?
The best way to avoid problems with user uploaded files of any kind is to have a command line virus scanner on the server, which you use to scan the files after upload. If the scanner result is positive, delete the file and so on
Take a look at Sophos API https://secure.sophos.com/partners/oem/integration/savdi.html
"SAV Dynamic Interface (SAVDI) provides an easy-to-integrate, general-purpose interface to the Sophos detection engine. It enables programs written in any language to scan files and data for malware and is particularly popular with ISPs/ASPs running in a .NET environment."
Another alternative is to use Process class to start an anti-virus scanner on the server (http://www.dotnetperls.com/process-start) and parse its results. For example, here's the list of command-line parameters for AVG: http://www.avg.com/ww-en/faq.num-3604.
By the way, as you develop your solution, you will need to test if you're able to identify an infected file. But it's not recommended to use a real infected file. However, you can create a text file with the string below. This string is commonly identified by anti-virus scanners as a infected file for testing purposes (for more information, search for EICAR Standard Anti-Virus Test File).
*X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H**