Why Unmask Parasites sometimes can't detect malicious content on sites that Google consider suspicious?
This can happen due to the following reasons:
- Unmask Parasites can't detect this sort of malware.
- Website doesn't contain malware at the moment but Google isn't aware of it yet.
- Website doesn't contain malware, Google knows about it but it takes time to unblock your site.
1. Unmask Parasites can't detect this sort of malware
Unmask Parasites is not a magic tool that can detect every possible hack. As an external scanner, it can only analyze HTML code of web pages and headers of HTTP responses. This is usually enough to detect the following security problems:
- hidden spammy links
- invisible iframes
- suspicious scripts
- unauthorized redirects
You should also realize that Unmask Parasites only checks one page at a time. If you can't see malicious content on one page, you might want to check some other pages.
Moreover, Unmask Parasites doesn't check external files like referenced by a web page: .js, frames and iframes, binary objects (.zip, .exe, .swf, .pdf, .doc, .xsl, etc.) Sometime malicious code can be found there. You should check such files yourself.
2. Website doesn't contain malware at the moment but Google is not aware of it yet
Google's warnings are not real time. They tell about a problem that Google detected some time ago. You can see this date on Safe Browsing diagnostic pages.
Moreover, Google doesn't scan your sites for malware every day. The next visit may only happen several weeks later (the web is big!). If you have cleaned up your site, you should explicitly request a malware review via Google's Webmaster Tools (Diagnostics->Malware). This way you can expect that Google will scan your site within 24 hours and remove the warning if your site is found clean.
Note, If you don't request the review, Google may leave a clean site blacklisted for a few more weeks - without your explicit request the issue is not considered resolved.
Read more about interpreting Google's malware warnings.
3. Website doesn't contain malware, Google knows about it but it takes time to unblock your site.
Google has a distributed system with many independent modules. It takes time to propagate changes. Sometimes all you should do is wait (usually a few hours).
Still not sure why your site is blacklisted and need someone to help you out?
You might want to request a consultation of the Unmask Parasites developer.