Cyberwarfare / Nation-State Attacks , Endpoint Security , Fraud Management & Cybercrime

State Hackers' New Frontier: Network Edge Devices

Firewalls, VPNs and Email Filter Resist Endpoint Scanning
State Hackers' New Frontier: Network Edge Devices
State hackers have shifted their attention to network edge devices, warns Mandiant. (Image: Shutterstock)

State-sponsored hackers have responded to improved network scanning by shifting their focus to edge devices characterized by patchy endpoint detection and proprietary software that hinders forensic analysis, warns Mandiant.

Russian intelligence hackers as well as Russian-speaking cybercriminals have targeted devices including firewalls, virtual private networks and email filters. Chinese hackers with Beijing's backing have particularly demonstrated in-depth knowledge of edge devices, the company says in an annual report laying out trends from its 2023 engagements.

Many devices such as VPNs often run for months without being rebooted, allowing hackers to gain persistence and remain in the target network without detection for a long time.

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"Attackers are focusing more on evasion," the report reads. They aim to avoid detection technologies such as endpoint detection and response and "maintain persistence on networks for as long as possible, either by targeting edge devices, leveraging 'living off the land' and other techniques, or through the use of zero-day vulnerabilities."

One side effect of the edge device focus: Phishing, although still exceedingly common, went down in 2023, according to Mandiant data. "For nation-state attackers, the focus has shifted to targeting commonly used low-visibility tools for stealth campaigns intended at data theft," said Stuart McKenzie, consulting managerial director for Mandiant Europe, Asia, and Africa.

Among threat actors favoring edge devices is a suspected Beijing espionage group tracked UNC3886. The group is behind a backdoor Mandiant calls calls Thincrust, malware that targets FortiManager and FortiAnalyzer devices by disguising the malware command and control as an API. The group also exploited a zero-day in VMware ESXi servers to access guest hypervisors using a customer malware called VirtualPita.

The group is behind a network redirection utility called TableFlip that contains a XOR encoded IP address that the group deploys alongside publicly available rootkits to act as a reverse shell on FortiManager devices.

Another suspected Chinese group tracked as UNC4841 has exploited a command injection zero day in Barracuda email security gateways to deploy a backdoor dubbed Depthcharge that survived a complete device replacement by infecting the backup configuration (see: FBI Urges Immediate Removal of Hacked Barracuda ESG Devices).

"Several aspects of DepthCharge demonstrated an intimate knowledge of the Barracuda ESG device and its software components," the report says. "Most notable was that the attacker had identified a method for malware persistence inside the configuration database for the appliance, which would result in it being present in the exported configuration."

Russian military intelligence threat group popularly known as Sandworm also uses compromised network edge infrastructure, in its case for wartime operations against Ukraine (see: The Global Menace of the Russian Sandworm Hacking Team).

Nation-state hacking easily grabs attention, but cyber defenders shouldn't overlook financially-motivated attacks, Mandiant says. Financially motivated groups such as FIN11 prioritize scale over stealth. The group was a key player in exploiting the zero day in the MOVEit file transfer service (see: Known MOVEit Attack Victim Count Reaches 2,618 Organizations).

Although ransomware hackers are among the most active financially-motivated threat groups, the report says there has been a significant slump in overall ransomware activities, including in the number of new variants detected.

Mandiant attributed this dip to a successful crackdown by law enforcement on groups such as Alphv last year.

Jamie Collier, senior threat intelligence advisor at Mandiant, said governments aiming to disrupt the ransomware ecosystem should pay attention to its many levels. "Sanctions are good," he said, "but it really takes a long time for them to be effective, so instead of targeting ransomware operators alone, law enforcement should equally pay attention to the role of access brokers in a cybercrime ecosystem and disrupt their activities for immediate results."

About the Author

Akshaya Asokan

Akshaya Asokan

Senior Correspondent, ISMG

Asokan is a U.K.-based senior correspondent for Information Security Media Group's global news desk. She previously worked with IDG and other publications, reporting on developments in technology, minority rights and education.

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