Web browsers such as Google Chrome or Mozilla Firefox use Google Safe Browsing to protect users before potentially malicious websites are loaded.
This works by checking sites against Safe Browsing's database to find out whether malware was hosted or distributed on the website in a 90 day period.
When you visit a flagged site in a browser supporting Safe Browsing, a warning page is displayed to you instead of the website itself.
Downloads on the other hand are blocked in Chrome when they are flagged, and the only option to complete a download is to open the download manager of Chrome to bypass the protection there.
The warning message
The warning depends on the nature of the attack. Phishing sites are for instance displayed in the following way:
Phishing attack ahead
Attackers on [domain-name] might try to trick you to steal your information (for example, passwords, messages, or credit cards).
It displays two options underneath: details and back to safety. Details adds more information and an option to visit the site regardless of the warning, while back to safety moves the user away from it without loading it.
Google Safe Browsing recently detected phishing on [domain-name]. Phishing sites pretend to be other websites to trick you.
If you understand the risks to your security, you may visit this infected site.
Manually checking links using Safe Browsing
Before we take a look at how you can check any link against Google's Safe Browsing database, we should answer the question why you may want to do so.
There are several answers to that. As a webmaster, you may want to check your domains against the database regularly to make sure that nothing slips by you. While you may receive the information in Google Webmaster Tools, you may not always have access to the administrative interface, especially if you are not the owner of the domain.
The diagnostic page can also be used to check a link without visiting it. If you have disabled Safe Browsing, for privacy purposes, or use a browser that does not support it, you may use the manual method to check a link for malicious contents.
To check any link, add it to the end of this url: https://www.google.com/safebrowsing/diagnostic?site= and load the resulting address in the web browser of choice.
The page answers the following questions:
- What is the current listing status for it?
- What happened when Google visited this site?
- Has this site acted as an intermediary resulting in further distribution of malware?
- Has this site hosted malware?
Google's Safe Browsing Diagnostic page is not the only option that you have to verify a url but it is straightforward and quickly done provided you know the core url of it.
I prefer to use Virustotal -- also a Google product now -- instead as it scans urls using more than 50 different engines and not just one increasing the chance that you are informed about malware or other malicious activities on it when you check it against the database.
Now Read: 5 Tips to stay safe on the Internet