USB Hack Spreads Cryptomining Malware

A sophisticated new cyber threat is turning unsuspecting computers into cryptocurrency mining slaves, and it all starts with a simple USB drive. Security researchers have uncovered a multi-stage attack where an infected USB device uses a clever Windows trick to install a hidden cryptominer, siphoning processing power and energy from victims.

The attack, analyzed by cybersecurity firm CyberProof, leverages a technique known as DLL search order hijacking. This method allows malicious actors to bypass standard security defenses, creating a stealthy backdoor for cryptojacking operations. The campaign has been observed targeting a range of critical sectors, making it a significant concern for organizational security.

How the USB Cryptomining Attack Unfolds

The infection chain begins when an employee plugs a malicious USB drive into their workstation. The attack is triggered not by hardware but by a disguised script file on the drive. Upon insertion, a VBScript file executes automatically or is manually run by a curious user.

This script activates a series of automated commands designed to trick the Windows operating system. A batch file is launched, which then uses a Windows system tool to copy a legitimate Windows file, printui.exe, into a newly created, slightly misspelled system folder. Crucially, a malicious file is also placed in this fake directory and renamed to mimic a critical system DLL.

When the copied program runs, Windows is tricked into loading the malicious DLL instead of the genuine one. This hijacked DLL contains code that silently downloads and executes a cryptocurrency miner, such as XMRig, consuming the computer’s resources to generate profit for the attackers without the user’s knowledge.

Key Industries in the Crosshairs

This USB-based threat campaign is not indiscriminate. Analysis of the attack’s indicators shows a focused effort on organizations where operational disruption is most costly. The primary targets include financial institutions, healthcare providers, educational establishments, and telecommunications companies. These sectors are attractive due to their large networks of powerful computers and the critical nature of their services, where downtime directly translates to financial loss.

Protecting Your Systems from USB-Borne Threats

Defending against this and similar threats requires a multi-layered security approach. Relying solely on employee vigilance is insufficient. Organizations must implement robust technical controls and enforce strict policies.

Endpoint Detection and Response (EDR) solutions have proven highly effective, as they can identify and block the obfuscated scripts and anomalous behaviors associated with this attack chain. Disabling the Windows AutoPlay feature for all removable drives is a critical first step to prevent automatic execution. Furthermore, organizations should enforce strict USB usage policies, potentially limiting port access physically or through software and mandating the use of company-approved, scanned devices.

Regular cybersecurity awareness training remains a cornerstone of defense, empowering employees to recognize the danger of unknown USB drives and report them instead of plugging them in.

Must Know

What is a USB cryptomining attack?
A USB cryptomining attack is a cyber threat where a malicious USB drive is used to install software that hijacks a computer’s processing power. This software, called a cryptominer, secretly uses the device’s resources to generate cryptocurrency for an attacker, slowing down the system and increasing energy costs.

How can I tell if my computer is infected with a cryptominer?
Common signs of a cryptominer infection include a significant slowdown in computer performance, overheating, unusually high fan activity, and a spike in electricity usage. The system may become sluggish and unresponsive even during simple tasks.

What should I do if I find a suspicious USB drive?
Do not plug a found USB drive into any computer. Immediately report it to your organization’s IT or security team. If at home, dispose of it safely. Plugging it in could compromise your personal device and network.

How can companies prevent these attacks?
Companies can prevent these attacks by combining technical and administrative controls. This includes deploying EDR tools, disabling AutoPlay, implementing strict USB device control policies, physically securing ports, and conducting continuous employee security awareness training.

Can antivirus software stop this threat?
A reputable, updated antivirus or anti-malware solution can detect and block many known cryptominers and the malicious scripts used to install them. However, advanced attacks may use evasion techniques, so antivirus should be part of a broader defense strategy that includes EDR.

Is this a new type of attack?
The specific DLL hijacking technique is not new and has been used by other cryptominer campaigns in the past. However, its delivery via a physical USB drive highlights the persistent risk of removable media and the need for continued vigilance.