Encryption protocols like SSL and HTTPs are designed to protect us when surfing the web, but increasingly these tools are being used by cyber-criminals to obfuscate their attacks, hide in networks and ultimately carry out more successful, prolonged attacks that evade detection.
Criminals are increasingly using encrypted channels to hide attacks or make them harder to disrupt.
One report from Ponemon Institute and A10 Networks in 2016 suggested as many as half of the cyber-attacks aimed at businesses in the previous 12 months had used malware hidden in encrypted traffic, echoing another study from Gartner in which the analyst group predicted that half of network attacks targeting enterprises would use encrypted traffic to bypass controls in 2017(a huge rise compared to just 5% in 2016).
From encrypted databases to images (Steganography) to conversations between nefarious actors on the network, encryption is as much a tool for bad as for good. Here, we look at how cyber-criminals are using different encryption protocols to scale-up their attacks:
How SSL Is Used in Attacks
Attackers have long been using SSL channels as part of a full attack cycle, from delivering exploits/payloads to pointing victims to phishing pages/compromised sites in a bid to fake authenticity.
In addition, many malware families are using SSL-based command and control (C&C) to reduce the likelihood of defense interference, while attackers commonly look to encrypt and leak confidential data and files using SSL connections when in the exfiltration stage, again in a bid to reduce defense visibility and the likelihood of disruption.
And to date, criminals have been relatively successful of using SSL to hide big attacks, such as the Zeus botnet.
So, why is SSL proving so successful for cyber crime? Well, simply put, organizations usually don’t often inspect SSL traffic because they assume that it comes from trusted sources. In short, they think it is secure and this, coupled with the increasing ease at which you can obtain legitimate SSL certificates, means that SSL is a common blind spot for CISOs and their teams.
Attackers are increasingly looking at how they can leverage SSL for the full delivery, from the start to the end. Take digital certificates as one example; recent research from Fidelis Security researcher Jason Reaves of Fidelis Security showed how it’s possible for SSL certificates to be used in such a way that they bypass traditional detection methods that don’t inspect certificate values.
It’s little surprise then that encrypted attacks are rising; An independent study by NSS Labs estimates that 25 to 35 percent of enterprise traffic is SSL encrypted and growing, with this peaking in certain verticals.
In addition, a recent SSL Threat Report from Zscaler found that the number of SSL-encrypted transactions concealing advanced threats had increased by 30 percent in the second half of 2017.
In its February 2018 SSL Threat Report, Zscaler tracked an average of 800,000 SSL-protected communications harboring malicious elements every day in H2 2017, marking a significant rise from 600,000 a day recorded over the previous six months.
How HTTPS Is Used in Attacks
HTTPS is fast becoming the standard of choice for safe web browsing. As noted by the recent Google Transparency Report, almost 80 percent of all pages loaded in Chrome over the past two months used HTTPS, with the search giant also increasingly penalizing publishers and website creators who don’t make the switch over from HTTP.
The problem, though, is that criminals are now creating attacks that rely on SSL to bypass corporate protections and infiltrate networks undetected.
Hackers now use HTTPS encryption to cover their tracks and get past firewalls, sandboxing technologies and behavior analytics tools. And, ultimately, it is a great and easy way to get malware onto the network without ringing any alarm bells.
There have been some notable attacks leveraging such techniques, including CryptoWall ransomware, and this is because defensive measures once thought effective are no longer properly doing their job. Firewalls, anti-malware solutions and IDS tools will often let HTTPS-traffic straight through, with even modern sandboxing technologies and behavioral analytics not configured to detect and neutralize HTTPS attacks.
So, what does this mean for businesses today? Ultimately, whilst encryption is essential, you must maintain a tight control over the digital keys and cryptographic certificates that enable encryption. You should also inspect and decrypt traffic on a regular basis, so you can detect and stop attackers before they take advantage of encrypted systems.