https://motherboard.vice.com/en_us/...o-install-backdoors-on-thousands-of-computers
Researchers at cybersecurity firm Kaspersky Lab say that ASUS, one of the world's largest computer makers, was used to unwittingly to install a malicious backdoor on thousands of its customers' computers last year after attackers compromised a server for the company's live software update tool. The malicious file was signed with legitimate ASUS digital certificates to make it appear to be an authentic software update from the company, Kaspersky Lab says.
The researchers estimate half a million Windows machines received the malicious backdoor through the ASUS update server, although the attackers appear to have been targeting only about 600 of those systems. The malware searched for targeted systems through their unique MAC addresses. Once on a system, if it found one of these targeted addresses, the malware reached out to a command-and-control server the attackers operated, which then installed additional malware on those machines.
"This attack shows that the trust model we are using based on known vendor names and validation of digital signatures cannot guarantee that you are safe from malware," said Vitaly Kamluk, Asia-Pacific director of Kaspersky Lab's Global Research and Analysis Team who led the research.
"We saw the updates come down from the Live Update ASUS server. They were trojanized, or malicious updates, and they were signed by ASUS," said Liam O'Murchu, director of development for the Security Technology and Response group at Symantec.
Kamluk said ASUS continued to use one of the compromised certificates to sign its own files for at least a month after Kaspersky notified the company of the problem, though it has since stopped. But Kamluk said ASUS has still not invalidated the two compromised certificates, which means the attackers or anyone else with access to the un-expired certificate could still sign malicious files with it, and machines would view those files as legitimate ASUS files.
Kamluk and Raiu said this may not be the first time the ShadowHammer attackers have struck. They said they found similarities between the ASUS attack and ones previously conducted by a group dubbed ShadowPad by Kaspersky. ShadowPad targeted a Korean company that makes enterprise software for administering servers; the same group was also linked to the CCleaner attack. Although millions of machines were infected with the malicious CCleaner software update, only a subset of these got targeted with a second stage backdoor, similar to the ASUS victims. Notably, ASUS systems themselves were on the targeted CCleaner list.
The Kaspersky researchers believe the ShadowHammer attackers were behind the ShadowPad and CCleaner attacks and obtained access to the ASUS servers through the latter attack.
