A lack of visibility into SSL traffic is creating security risks around encrypted HTTPS web connections, according to the security company Blue Coat Systems.

The firm warned that the cover provided by the security layer of "always on" HTTPS connections, used by the likes of Google, Amazon and Facebook, means that hackers can enact simple malware attacks without fear of getting caught in what is said to be a growing problem for business

Hugh Thompson, chief security strategist for Blue Coat, said: "The tug of war between personal privacy and corporate security is leaving the door open for novel malware attacks involving SSL over corporate networks that put everyone’s data at risk.

"For corporations to secure customer data and meet regulatory and compliance requirements, they need the visibility to see the threats hiding in encrypted traffic and the granular control to make sure employee privacy is also maintained."

Blue Coat added that the trojan Dyre, recently thought to have targeted users of the software vendor Salesforce, was making use of the encryption blind spot with the capacity to steal banking information, health data, and intellectual property.

At the end of last year SSL web traffic accounted for 15-25% of the total, according to the research firm Gartner. By 2017 half of network attacks against businesses are expected to bypass controls through traffic encryption.