Possible Duplicate:
My server's been hacked EMERGENCY
I have been design an asp.net site with .net framework 3.5 all thing is good until my site hacked suddenly it says a chines group and some other text by picture jpg they put files into the ftp server I delete them and they put them again I change all password and they do it again I think they are some script programmer and I can do nothing by deleting method, please help me.
I think it's pretty clear that you don't have the technical skills to be able to complete this job -- it's a difficult problem, with many potential areas of exploration and avenues of attack that need to be secured. I would recommend engaging the services of an experienced systems administrator to investigate these options, cleanup the infection, and deploy the appropriate safeguards to prevent it happening again.
They replaced default.aspx instead of my default.aspx I have upload or script uploading I don't know exactly whay they are doing some complex operation.
As a developer, you should know if your app is secure or not. In the other hand, even if you have the most perfect and protected app, if there is a huge hole at system level, your programming skills won't worth too much and you'll be cracked anyway. Just hire a sysadmin so your system can be properly secured.
Yes womble I know I am developer not system administrator but I don't know where is the hole they attack again and again I think it is more complicated that you can explain but I want to know about how to prevent I know how to pay for system administrator and how to find him I want to know how they attack I had upload by some script on the ftp server by Injection or not some else method ?
