Acunetix Vulnerability Scanner v10 (On premise) and (Online) includes a malware detection service that detects URLs linking to external sites known to host malware or that are known to be used for phishing attacks. Such links may indicate that the site being scanned has either been compromised, or that somehow an attacker has managed to inject URLs to the malicious site. It may also indicate that a legitimate site that your site links to has been compromised and is hosting malware.
In order to provide the detection of malicious or phishing URLs, the Acunetix malware detection service makes use of the Google Safe Browsing database and the Yandex Safe Browsing databases.
When Acunetix detects a malicious URL, you should stop linking to the affected URL as this will affect your users who might trust the malicious site since your site is linking to it. Your website’s Search Engine Optimization (SEO) ranking might also be affected when linking to malicious sites. If you happen to know the owner of the site, you might want to suggest running a virus scan on the site. If the site is making use of Google Webmaster Tools (or a similar service), this might provide more insight on the infection.