Unfortunately recently a customer's website has been reported as Suspicious by Google and blacklisted, Google webmaster tools does not show any information on the infection or when it was detected, it just say that there is an unknown malware leading to a huge loss in income.
I've no idea on how to check if there is actually something malicious in the website, the code seems clean and there are no changes in the creation or modification times of the PHP source code files.
I've also done several anti-virus checks with many services included VirusTotal and ESET end point.
Any of you had a similar problem and can point me into the right direction?
Thank you all in advance.
The website has no CMS, is mostly custom PHP with content written in the template files, it had a link to Ammyy software since a lot and has been removed as it may be reported as Trojan from some antivirus softwares, still nothing changed from Google perspective.
Google lifted off the ban without explaining nothing actually. The only information we got is that for Google a site that was linked to it had a link, again, to Ammy but it was removed as per 2015-12-18, even if the linked website was not marked as suspicious it required to be linked on Webmaster Tools for "Fetch as Google".
Hope that helps.