My blog i.e. blog.site.com is affected with virus but my original site i.e www.site.com have no such problem. But I got the reminder from the Google in my website webmaster account that some of your website part is affected with virus. Please explain why..and how i resolve this issue.
pls scan your blogs code with good anti virus and for solving this problem you should use google webmaster tools.
Check with your hosting provider. Bigger hosting companies will have some tools to help you scan. Small hosting companies will fix it for you! Sometimes, when you are dealing with malware on a site, it is necessary to load from back-ups I hope you have those. Look closely to see which domains are being called when your site is loaded, check the Google Cache, and monitor IP's logging into your site.
Yes web hosting will affect your web sites with malware attacks to resolve this problem contact to your web hosting provider,to avoid re-happening it try to avoid editing your web site with untrusted ftp accounts and try to use Cpanal for this,before uploading any kind of file on web site scan that,try to host your web site at dedicated server.
scan all of your blogs code with antivirus and check out the adds as well because it can come from anywhere in your blog
Apart from the advice that others are giving to resolve the issue, I believe you ask why the blog is infected and your website isn't, and why you get the warning from Google on your main site. First: the blog is on blog.site.com - that is a DIFFERENT site from www.site.com, and it is irrelevant that the subdomain may be located in a subdirectory of www.site.com. That's why one may be infected but not the other. (assuming there is no code injection in the blog). Second: You get the warning in your website webmaster account because you do not have two accounts (one for the blog and another from the main website). You either have both the main domain and subdomain registered in your webmaster account or you have marked the blog as part of the sitemap or have multiple direct links from your main site. Google detects the infection and reports it to the only account it knows that is related to your site. Apart from the advice given above about how to resolve the issue, check out the comments for "funny" stuff - somebody might have embedded code inside his comment...
It's mostly affected the index pages of your blog, in past some malicious codes hit the sites.. mostly coming from .ru sites.. so you should be checking index, default kind of pages.. or if you have ssh.. check iframe, .ru possibilities on each page.. once you think it's clean you can go to webmaster and proceed to reconsider request
Glad to know you got the solution, we wasted so many man hours cleaning sites for such virus attacks...