I understand SSL Web browsers can serve as vectors for malware. Can you explain how that works and how we can prevent malware from infiltrating a network via SSL traffic?
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Web browsers have included support for the Secure Sockets Layer (SSL) protocol, which is a method for encrypting data, since Netscape introduced SSL v2.0 in 1996. Other protocols typically use it to encrypt the contents of the traffic, such as malware content being served over a HTTPS connection to a Web browser. This encryption protects the privacy and security for users, but in the case of malware, it prevents network inspection tools from analyzing the contents of the network for malware. Smart attackers encrypt their communications, using HTTPS to hide their traffic from detection. That malware is transmitted over HTTPS to a Web browser on an endpoint that does not indicate any issues with HTTPS, identify SSL malware per se, or any other SSL security issues, but only identifies an issue with the security of the endpoint and network security controls in place.
I have discussed Web browser security controls for endpoints in previous questions, but there are some network security controls that prevent malware from infiltrating via SSL-encrypted traffic. Most signature-based network security tools cannot identify malware in a HTTPS connection, but a Web proxy with SSL inspection functionality could be used to analyze the content for malware. Behavioral-based network security tools do not have this same limitation. You could also use IP or DNS-based blacklists to prohibit websites that host malware, but this might block legitimate Web traffic.
This was first published in May 2012