There is a new advanced persistent threat (APT) campaign funneling through the supply chain that could be affecting over one million users, researchers said.
Attackers behind Operation ShadowHammer targeted users of the ASUS Live Update Utility, by injecting a backdoor into it, at least between June and November 2018, said researchers at Kaspersky Lab, who estimate the attack may have affected more than a million users on a global basis.
A supply chain attack is one of the most dangerous and effective infection vectors, increasingly exploited in advanced operations over the last few years. It targets specific weaknesses in the interconnected systems of human, organizational, material, and intellectual resources involved in the product life cycle: from initial development stage through to the end user. While a vendor’s infrastructure can be secure, there could be vulnerabilities in its providers’ facilities that would sabotage the supply chain, leading to a devastating and unexpected data breach.
Attackers behind ShadowHammer targeted the ASUS Live Update Utility as the initial source of infection.
This is a pre-installed utility in most new ASUS computers, for automatic BIOS, UEFI, drivers and applications updates. Using stolen digital certificates used by ASUS to sign legitimate binaries, attackers tampered with older versions of ASUS software, injecting their own malicious code. Trojanized versions of the utility were signed with legitimate certificates and were hosted on and distributed from official ASUS update servers – which made them mostly invisible to the vast majority of protection solutions.
While this means potentially every user of the affected software could have become a victim, attackers behind ShadowHammer focused on gaining access to several hundreds of users, which they had prior knowledge about. Each backdoor code contained a table of hardcoded MAC addresses – the unique identifier of network adapters used to connect a computer to a network, Kaspersky Lab’s researchers said.
Once running on a victim’s device, the backdoor verified its MAC address against this table. If the MAC address matched one of the entries, the malware downloaded the next stage of malicious code. Otherwise, the infiltrated updater did not show any network activity, which is why it remained undiscovered for such a long time. In total, researchers were able to identify more than 600 MAC addresses. These were targeted by over 230 unique backdoored samples with different shellcodes.
The modular approach and extra precautions taken when executing code, to prevent accidental code or data leakage, indicates it was very important for the attackers to remain undetected, while hitting some very specific targets with surgical precision, researchers said. Deep technical analysis shows the arsenal of the attackers is very advanced and reflects a very high level of development within the group.
The search for similar malware has revealed software from three other vendors in Asia, all backdoored with very similar methods and techniques. Kaspersky Lab has reported the issue to Asus and other vendors.
“The selected vendors are extremely attractive targets for APT groups that might want to take advantage of their vast customer base,” said Vitaly Kamluk, director of global research and analysis team, APAC, at Kaspersky Lab. “It is not yet very clear what the ultimate goal of the attackers was and we are still researching who was behind the attack. However, techniques used to achieve unauthorized code execution, as well as other discovered artefacts suggest that ShadowHammer is probably related to the BARIUM APT, which was previously linked to the ShadowPad and CCleaner incidents, among others. This new campaign is yet another example of how sophisticated and dangerous a smart supply chain attack can be nowadays.”