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FBI Attribution of 'VPNFilter' Attack Raises Questions

Information shared by the FBI on the massive VPNFilter attack in which more than half a million devices have been compromised raises some interesting questions about the connection between Russia-linked hacker groups.

The existence of VPNFilter was brought to light last week by Cisco Talos and several other cybersecurity firms. The botnet is powered by at least 500,000 hacked routers and network-attached storage (NAS) devices across 54 countries.

The malware can intercept data passing through the compromised device, it can monitor the network for communications over the Modbus SCADA protocol, and also has destructive capabilities that can be leveraged to make an infected device unusable.

Many of the hijacked devices are located in Ukraine and a separate command and control (C&C) infrastructure has been set up for devices in this country. Researchers also spotted code similarities to the BlackEnergy malware and pointed out that there are only a few weeks until Ukraine celebrates its Constitution Day, which last year coincided with the destructive NotPetya attack. All this has led experts to believe that VPNFilter may mean Russia is preparing for a new attack on Ukraine.VPNFilter

Shortly after security firms published technical details on the attack, the U.S. Department of Justice announced that the FBI had seized toknowall.com, one of the C&C domains utilized by VPNFilter.

A press release and court documents name the Russia-linked threat actor Sofacy as being behind the attack. While this is not surprising, one noteworthy piece of information is that U.S. authorities say Sofacy is also known as APT28, Pawn Storm, Fancy Bear, Sednit, X-Agent, and Sandworm.

Sandworm, also tracked by some security companies as TeleBots, is a threat actor known to use the BlackEnergy malware in attacks aimed at industrial systems and it’s believed to be responsible for the 2015 power outage in Ukraine. However, Sandworm was until now seen as a separate group from Sofacy.

SecurityWeek has reached out to the Justice Department and the FBI for clarifications, but the organizations say they “do not have a comment outside what is included in the DOJ press release.”

Industry professionals, however, have offered some possible explanations as to why the FBI may see Sofacy and Sandworm as the same group.

“Sandworm is a similar team whose interests overlap with APT 28. We believe these actors are related and act accordingly,” Craig Williams, director of outreach with Cisco Talos, told SecurityWeek.

Vikram Thakur, principal research manager at Symantec Security Response, noted, “The intelligence community has the best shot at attributing attacks to individuals and organizations. Every security vendor groups attackers based on their own vantage into the attack landscape.

“Keeping in mind that attack groups themselves share knowledge, expertise, and resources, we don’t have any reason to question the grouping of Sofacy, Sandworm, X-Agent, and others that the FBI listed in their affidavit to seize a domain related to VPNFilter.”

Researchers at Kaspersky also found it curious that the FBI suggested Sandworm and Sofacy were one and the same.

“This would suggest that Sandworm, also known as BlackEnergy APT, is regarded as subgroup of Sofacy by the FBI,” Kaspersky researchers said. “Most threat intel companies have held these groups separate before, although their activity is known to have overlapped in several cases.”

Advice from the FBI and targeted device vendors

Rebooting a router is typically enough to remove a piece of malware from the device. However, VPNFilter has some clever persistence mechanisms that help its stage 1 component survive a reboot.

An alert issued on Friday by the FBI advises owners of small office and home office routers to reboot their devices to “temporarily disrupt the malware and aid the potential identification of infected devices.”

“Owners are advised to consider disabling remote management settings on devices and secure with strong passwords and encryption when enabled. Network devices should be upgraded to the latest available versions of firmware,” the FBI said.

The VPNFilter malware has been observed targeting devices from Linksys, MikroTik, Netgear, TP-Link and QNAP. All of these vendors have published advisories to warn their customers about the threat.

There is no evidence that the malware exploits any zero-day vulnerabilities to hack devices. Affected vendors noted that the flaws targeted by VPNFilter have already been patched and advised customers to update the firmware on their devices.

Related: Sofacy Attacks Overlap With Other State-Sponsored Operations

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.