Old malware, new tricks

Taking the path of least resistance is natural – it’s why rivers flow around mountains, and electricity finds the easiest route to earth. It also explains why there has been such an explosion in new malware in the past couple of years. While there remains a select handful of coders who will painstakingly develop sophisticated, advanced and complex new threats the vast majority of would-be hackers are taking a much easier route to achieve their goals.

They’ve seen the rewards that are possible from a malware attack, and they’re also aware of the easily-available tools that automate the assembly of new malware, or enable small modifications to existing malware types, rendering them undetectable by conventional antivirus products. The result is that malicious code is now being mass-produced and unleashed on an industrial scale, by people with little or no coding skills.

In fact, Check Point’s latest annual Security Report shows that more unknown malware has been found in the past two years than in the previous 10 years combined. While new malware introductions were relatively static in 2010 and 2011, at 18 million per year, this nearly doubled to 34 million in 2012, rose to 83 million in 2013, and reached 142 million in 2014. What’s worse is the speed at which this is occurring. On average, organisations were downloading 106 unknown malware types every hour – that’s 48 times more than in 2013.

In a majority of cases, these were existing, known types of malicious files that had simply been modified with minor alterations to a couple of lines of their code – literally, old malware with a new trick, that enabled it to bypass even the most up-to-date antivirus detection.

Building a better trap

To avoid being fooled by these new tricks, an additional method of detection known as threat emulation, or sandboxing, is recommended. Early versions of this technology worked by intercepting suspicious files as they arrived at the organisation’s gateway, and inspected their contents in a virtualised, quarantined area (the sandbox) for any unusual behaviour, in real time. If the file’s behavior was found to be malicious, for example attempting to make abnormal registry changes or network connections, it would be quarantined, preventing the infection from reaching the network.

While this approach considerably boosts malware detection rates, criminals have already recognised that the technology is deployed on a percentage of networks, and have responded by implementing further evasion techniques. As such, a next-generation approach is being introduced: CPU-level sandboxing. This enables a deeper, more insightful look at a suspicious file’s activity.

It takes advantage of the fact that there are only a handful of exploitation methods that can be used to download malware and execute it on a host PC. As it operates at the chip level, below the application or operating system layers, CPU-level sandboxing detects the use of malware exploitation methods by examining activity on the CPU, and the execution flow at the assembly code level while the exploit occurs. As a result, it strips away any disguises applied to the malware, and pre-empts the possibility of hackers evading detection.

While the speed and accuracy of detection make CPU-level sandboxing a powerful method for detecting unknown attacks, especially existing malware that has been altered using obfuscation tools, it also enables detection of the far more sophisticated (and much rarer) zero-day exploits. Zero-day malware is effectively hand-built to exploit software vulnerabilities that vendors aren’t even aware of yet. The ability to block both common and rare, targeted attacks adds a strong, extra defensive layer to organisations’ networks.

Taking the sting from malware

Taking this approach a step further, another emerging threat prevention technique can combine with OS- and CPU-level sandboxing, to virtually eliminate the risk of threats. This technique is called threat extraction.

It involves a direct approach to threat removal: as the majority of malware is distributed in infected documents (our Security Report shows that 55% of all infected files were PDFs or Office files), then all documents arriving at an organisation by email should be intercepted, and content that is identified as malware, such as macros, embedded objects and files, and external links, removed. The threat-free document can then be reconstructed with known safe elements, and forwarded to the intended user, either in the original format or as a locked-down PDF, according to the organisation’s policies.

With the pace of malware attacks showing no signs of slowing down and the evasion techniques and tricks used by malware authors always evolving, the technology deployed to keep businesses secure also needs to evolve, to keep them ahead of new threats. What was cutting edge in 2014 will simply be the standard for 2015.