Conventional network endpoint defense used to rely largely on the basic fact that computers primarily used files to communicate. Files were not only transmitted to and from other systems, but also to a system’s local storage devices, such as a laptop’s hard drive.

Endpoint defense could thus concentrate on checking incoming file traffic for telltale signs of a malicious file. This is how both ordinary antivirus software and sophisticated signature-based tools operated.

Fileless Malware Slips Past the File Sentries

A new generation of so-called fileless malware has emerged, taking advantage of dynamic environments in which external data streams may go directly into memory without ever being stored or handled as a file. Web-based scripts, containers and microservices are all examples of environments in which fileless malware can be propagated.

According to Infosec Island, fileless malware not only can slip into a system without being detected by file-based endpoint security, but it can also make itself persistent by exploiting Windows registry entries. Even rebooting the computer, which will wipe out any purely memory-based malicious code, will merely reload malicious registry entries.

Extending the Principle of Layered Protection

In response to this threat, a new generation of endpoint protection is emerging that combines traditional, file-based layered security with machine learning and threat detection sandboxing.

Machine learning technology in isolation is not enough, because the emergence of new threat vectors, such as scripts, does not mean that file-based malware is going to disappear. Infosec Island warned that “relying on an endpoint protection platform that uses only machine learning will not harden the overall security posture of an organization.”

Malicious actors will continue to use both modes of attack, since they are equally well-suited to social engineering delivery techniques including spear phishing emails and webpages with malicious scripts.

The emergence of the fileless malware threat and the protective measures taken in response to it are the most recent iterations of two ongoing themes in network security. One is that networks and the overall computing ecosystem are becoming more richly connected. Endpoint security then becomes more complex.

Meanwhile, the principle of layered security remains valid. The more opportunities taken to interpose protective measures, the greater the likelihood that attacks will be detected and blocked. There are no magic shields, but over the long run, vigilance and active defense pay off against fileless malware as well as more traditional modes of attack.

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