Fileless Cyberattacks: They're Getting More Widespread and They're Working

Fileless Cyberattacks: They're Getting More Widespread and They're Working

Reports from Ponemon Institute and McAfee Labs have shown that fileless cyberattacks are getting more widespread and they're working.

What Are Fileless Cyberattacks?

Fileless cyberattacks, also known as zero-footprint attacks, refer to cyberattacks that are meant to evade detection by avoiding to install at one stage or another malicious software (malware) on the victims’ computers.

McAfee Labsreported that there’s a significant shift by some cyberattackers toward exploiting trusted Microsoft’s proprietary programs, rather than installing external malware, to attack computers or office computer networks.

In the Ponemon Institute’s study “The 2017 State of Endpoint Security Risk”, researchers found that 77% of successful cyberattacks in 2017 used fileless techniques. The study found that fileless attacks are almost 10 times more likely to succeed than file-based attacks.

The terms “fileless” and “zero-footprint” are misnomers. Fileless cyberattacks don’t mean that they’re exclusively fileless at every stage. For instance, the attack may start with the opening of a malicious file to a spam email and once the infection starts though, the attackers may shift to fileless techniques.

Attackers can also gain access to victims' computers by compromising the victims' computers filelessly at the beginning of the attacks, for instance, by exploiting a security vulnerability that's unpatched and then once access is achieved, external malware is then installed.

Fileless cyberattacks aren’t also necessarily “zero-footprint” because fileless cyberattacks do leave traces on the victims’ computers if one knows where to look.

There’s, however, justification to the name “fileless cyberattacks” as these attacks don’t exhibit the usual symptoms normally associated with malware infection on the computer disk. As they’re asymptomatic, they’re hard to detect and as such, traditional anti-virus solutions can’t detect them.

Instead of installing the malware into the computer disk, what a fileless attack does is embed the malware in scripts or install the malware into the computer memory and never gets copied to the disk, thereby bypassing endpoint security measures such as anti-virus, which typically rely on file input/output to detect threats.

Examples of Fileless Cyberattacks

Below are examples by which attackers infect victims’ computers filelessly:

1. Fileless Cyberattacks via Microsoft’s Windows PowerShell

One of the ways by which attackers infect victims’ computers filelessly is via Microsoft’s Windows PowerShell.

Microsoft’s Windows PowerShell is Microsoft’s task automation and configuration management framework. Available on Windows 7 onward, Microsoft PowerShell allows full access to Microsoft COM (Component Object Model) and Microsoft Windows Management Instrumentation (WMI). Attackers can access Windows features using Microsoft PowerShell.

One preventive measure in protecting Microsoft PowerShell from fileless cyberattacks is by setting it to "Restricted". According to McAfee Labs, attackers can easily get around this restriction by performing “remote execution of a script by directly executing it in memory to bypass endpoint security.”

System administrators bypass the Microsoft’s Windows PowerShell restriction, in the same manner, to execute commands on office computer networks from a remote location via the internet.

2. Fileless Cyberattacks via Microsoft’s Remote Desktop Protocol (RDP)

Another way by which attackers infect victims’ computers filelessly is via Microsoft’s Remote Desktop Protocol.

Microsoft’s Remote Desktop Protocol, just like Microsoft’s Windows PowerShell, is a proprietary software developed by Microsoft. And just like PowerShell which is primarily used by system administrators, Remote Desktop Protocol is also used by systems administrators to access other computers or office computer networks from a remote location via the internet.

Attackers gain access to victims' computers via Microsoft’s Remote Desktop Protocol by simply guessing their way past weak passwords or by using popular password cracking tools. McAfee Labsreported that thousands of these Remote Desktop Protocol login details (specifically for Windows XP through Windows 10 and Windows 2008 and 2012 Server) are sold online between $3 to $19.

Once attackers gain access to your organization’s computer network via Remote Desktop Protocol, they can do anything with it such as install any malware of their choice.

In both fileless cyberattacks via Microsoft Windows PowerShell and Microsoft Remote Desktop Protocol, once attackers gain access into victims’ computers, they’re viewed as system administrators, masking the identity of the attackers, allowing them to hide in plain sight.

3. PowerGhost

PowerGhost is a cryptocurrency mining malware – a malicious software that hijacks the processing power of victims’ computers. Kaspersky Lab first identified this malware.

This malware spreads across large corporate networks infecting both workstations and servers by using a number of fileless techniques, including Mimikatz, a hacking tool designed to siphon a Windows user's password out of the computer's memory.

PowerGhost propagates itself across the local network by launching a copy of itself via Microsoft’s Windows PowerShell and via the now-notorious EternalBlue exploit – a spy tool believed to be developed by the US National Security Agency (NSA) and leaked by the hacking group Shadow Brokers in April 2017. On March 14, 2017, a month before Shadow Brokers leaked the EternalBlue code, Microsoftreleased a security update or patch fixing the security vulnerability exploited by EternalBlue.

Prevention against Fileless Cyberattacks

As shown in the above-mentioned examples, attackers use a number of techniques for fileless attacks. Here are some of the preventive measures against fileless attacks:

• Keep all your software up-to-date.

By keeping your software up-to-date, your organization’s computer network won’t be vulnerable against EternalBlue exploit.

• Use complex passwords and two-factor authentication to prevent attackers’ entry.

• Eliminate unlimited login attempts by timing out IPs or blocking or locking out users that have too many failed login attempts.

• To prevent attackers’ entry via Microsoft’s Windows PowerShell, consider using Constrained Language Modeto limit PowerShell to basic functionality. This makes many fileless attacks via Microsoft’s Windows PowerShell unusable.

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