Fileless Attacks: How do you protect your organisation from a threat you can’t see?

Fileless Attacks: The Threat You Can’t See

Fileless attacks are on the rise. A study by the Ponemon Institute found that 29% of the attacks faced by organisations during 2017 were fileless. This number has been increasing year on year and is expected to reach 35% in 2018.

The reason for this increase is simple. Hackers know they stand a greater chance of succeeding with a fileless attack because they are more difficult to detect. Traditional anti-malware and anti-virus tools search for malicious software by scanning a computer’s hard drive. This has led cybercriminals to pursue attacks that avoid the hard drive altogether.

How do file-less attacks work?

To avoid the hard drive, hackers hide malicious code in memory instead, using authorised native programs and tools within the operating system to attack by stealth.

This is how an attack against your organisation could occur:

  1. An employee receives a spam email with a link to a malicious website.
  2. The employee clicks on the link.
  3. The malicious website loads an authorised program, such as Flash, on the employee’s computer and exploits its known vulnerabilities.
  4. The program then opens Windows PowerShell, a native Windows tool, which is able to execute instructions through the command line while operating in memory.
  5. PowerShell downloads and runs a malicious script.
  6. The PowerShell script locates data on the employee’s computer and sends it to the attacker.

Using authorised applications already installed on the target’s computer is more discrete than placing a file on the user’s computer. The hacker can undertake the same types of attack as they otherwise could, such as ransomware attacks for example, but is far less likely to be noticed. This is why it is essential to swiftly patch and update your operating systems and software applications.

Although not truly a ‘fileless’ attack, the same attack could occur if an employee opens a Word or PDF document sent from a malicious source. With a Word document for instance, the attack will use a Microsoft Office macro to launch PowerShell and run the hacker’s script. Programmes such as Adobe PDF Reader and Javascript all have known vulnerabilities which hackers seek to use to their advantage.

Fileless attacks will continue to rise until organisations become effective at identifying and defending themselves from this type of attack. Cybersecurity tools that learn and analyse patterns of behaviour are better placed to spot unusual activity on your networks, which could afford some protection against fileless attacks.

However, relying on cybersecurity tools alone is not enough. Training staff to recognise fraudulent and spam emails also needs to be a crucial element of your cybersecurity strategy. Spam emails are becoming less obvious to spot, often looking near identical to emails from a legitimate source. The few seconds it takes an employee to check the sender’s email address is accurate could be the difference between a successful and unsuccessful attack against your company.

As new modes of threat emerge, organisations must rethink the ways they protect themselves, and analyse the cybersecurity tools they use.