Security researchers believe a supply chain attack known as Operation ShadowHammer may have distributed a backdoor to more than 1 million users.

Kaspersky Lab first discovered Operation ShadowHammer back in January 2019. The attackers behind the campaign directed their supply chain attack against the ASUS Live Update software, a utility that comes preinstalled on most computers built by ASUS. The software automatically receives updates for certain components, such as the Basic Input/Output System (BIOS), Unified Extensible Firmware Interface (UEFI) and other applications.

Kaspersky Lab observed 57,000 users of its security products who had installed the backdoor on their machines. The security firm can’t calculate the total number of users affected by the attack from just its own data, but it estimated that the campaign could have affected at least 1 million users. Even so, Kaspersky Lab found in its analysis that the likely goal of Operation ShadowHammer was to target an unknown pool of users via their network adapters’ media access control (MAC) addresses.

The Dangers of a Supply Chain Attack

Operation ShadowHammer isn’t the only sophisticated supply chain attack that’s emerged in the past few years. In September 2017, researchers at Morphisec reported that threat actors had succeeded in covertly modifying the Avast-owned security application CCleaner with a backdoor. This attack subsequently linked as many as 2.27 million users to a server under the attackers’ control.

A few months prior, wiper malware known as Nyetya/NotPetya affected many organizations and multinational corporations operating in Ukraine. Researchers at Cisco Talos launched an investigation into some of the key aspects of this outbreak and discovered that malefactors had conducted a supply chain attack against MeDoc, the makers of a Ukranian accounting software package, to produce a malicious update disguised as ransomware and serve this payload to the software’s users.

Blocking Attacks Like Operation ShadowHammer

Security professionals can help defend against campaigns similar to Operation ShadowHammer by continuously monitoring their third-party connections. In doing so, security personnel should use firewall rules and other common methods to stay on the lookout for inbound connections.

Organizations should also invest in an artificial intelligence-based detection solution that can analyze networks for suspicious behaviors that a human eye might miss and protect the organization against sneaky digital threats like zero-day malware.