Cyberspies Stole Legit Digital Certificates To Mask Their Malware

The nation-state group behind the new Duqu 2.0 attacks used a legitimate digital certificate pilfered from one of the world's largest electronics manufacturers as a way to maintain a silent and persistent foothold in its victims' networks.

Costin Raiu, director of Kaspersky Lab's global research and analysis team, today revealed that his team had discovered a major piece of the puzzle in a wave of targeted cyber espionage attacks that hit international participants at the Iranian nuclear negotiations and other organizations, as well as Kaspersky's own corporate network, in an apparent attempt to gather intelligence on the firm's latest technologies and research.

The malware used in Duqu 2.0 runs only in memory of a victim's machine, but the attackers also employ a unique method of retaining presence in the victim's network once they gets inside and even after an infected machine is rebooted and cleaned up, according to Raiu. The nation-state attackers install malicious drivers signed by Hon Hai Precision Industry Co. Ltd., aka Foxconn Technology Group, the world's largest electronics manufacturer best known for building Apple iPhones and iPads, but which also boasts Microsoft, Acer, Amazon, BlackBerry, Cisco, Dell, Google, HP, Motorola and Sony as its customers.

The drivers are installed on firewalls, gateways, and other Internet-facing servers, to appear as legitimate firmware updates on those devices. The endgame is for the attackers to remain hidden inside their target and to provide a command-and-control operation, according to Raiu.

"We were able to uncover during our investigation … a 64-bit driver they used for persistence" and hiding command and control connections as well as camouflaging log activity, Raiu says. That's the very same strategy employed in the first-generation of Duqu thought to be a precursor to the Stuxnet attack. The attack back then used stolen Jmicron and Realtek digital certificates to sign the malware so it would appear legit.

Raiu says it's unclear whether Foxconn was a victim of the Duqu malware attack, but his firm has alerted the driver manufacturer as well as Verisign of the abused cert. The Foxconn cert is currently in the process of being revoked by Verisign, he says.

The stolen certificate strategy demonstrates a trend in how the Duqu attackers try to operate under the radar in their targets' networks, he notes.

"In essence, the drivers are redirecting network streams to and from the gateway machine that runs it. To forward connections, the attacker has to pass a network-based 'knocking' mechanism by using a secret keyword," Raiu and his team said today in a new blog post with the technical details. "We have seen two different secret keywords in the samples we have collected so far:  'romanian.antihacker' and 'ugly.gorilla.'"

[Nation-state campaign with previous ties to Stuxnet spies on security firm's research and anti-cyber spying technologies -- plus participants in Iranian nuclear negotiations and their telecommunications, mobile providers. Read Duqu 2.0 Attack On Kaspersky Lab Opens Chilling New Chapter In Cyber Espionage.]

Another intriguing -- and alarming -- tidbit:  the Duqu gang doesn't use the same digital certificate twice, which could mean they have a stockpile of stolen digital legitimate certificates it can use in future attacks, Raiu says.

"As long as the attacker has unlimited certificates, that means digital certificates are no longer an effective way of demanding networks to validate … software," he says.

Meanwhile, Kaspersky also has spotted an ICS/SCADA hardware vendor in the Asia Pacific region that has been infected by Duqu 2.0. "They [the attackers] have a special interest of infecting hardware manufacturers in the APAC region," says Raiu, who declined to name the targeted ICS/SCADA vendor.

He says the stolen certs are not likely related to the mysterious Duqu 2.0 module that appears to have an ICS/SCADA connection. The acronym "HMI" appears in the filename, suggesting its purpose has to do with ICS/SCADA systems, but Raiu says he's still investigating it. "That module appears to target some SCADA hardware," he says.

Nor has Kaspersky been able to get to the bottom of exactly what the attackers are after, or whether Duqu 2.0 is a precursor to a cyber-sabotage attack akin to Stuxnet. "This is why this [mysterious] module is so interesting," Raiu says. "When we figure out the exact purpose of these files we might be able to understand what is the purpose of [infecting] the hardware, where it's used, and to be able to understand if it's used for sabotage or information-gathering."

Security experts say the successful attack of Duqu 2.0 on a security company is a red flag for the types of attacks on the horizon.

"It's fascinating how an AV company [Kaspersky Lab] had identified previous variants of the same malware family yet were still challenged to immediately detect and prevent a variant of it months after the campaign," says Ryan Kazanciyan, chief security architect at Tanium, who previously worked for Mandiant. "The takeaway is not how to stop a zero-day better, but how to better prevent and detain intrusions."