Inside the North Korean Hacking Operation Behind SWIFT Bank Attacks

FIREEYE CYBER DEFENSE SUMMIT – Washington, DC – Researchers at FireEye here today shared details about how a North Korean hacking team they have christened APT 38 has attempted to pilfer $1.1 billion from financial institutions worldwide.

FireEye previously had attributed the game-changer cyberattacks on the SWIFT international interbank messaging system in various banks to a North Korean hacking group it calls TEMP.Hermit, which mostly had conducted cyber espionage attacks against energy and the defense sectors in South Korea and the US.

APT 38's main objectives, however, are financially motivated on behalf of the North Korean government: Since 2015, the hacking team has stolen hundreds of millions of dollars from at least five banks (including Bangladesh Bank and Banco de Chile) and has hacked into 16 organizations in 11 countries in Latin America and Europe, plus the US, for example, according to FireEye.

"This is the first time we've seen a cybercrime group essentially funding a regime," said Nalani Fraser, manager of threat intelligence at FireEye, of the North Korean group.

North Korean nation-state hacking teams typically get lumped together under the name Lazarus Group, the group behind the epic breach, doxing, and data-wiping attacks on Sony Pictures Entertainment in 2014 and WannaCry in 2017. It was after the Sony breach that North Korea's hacking machine began to split into different groups, according to FireEye's analysis, and APT 38 began to emerge as an entity. APT 38's rise coincided with financial pressures due to international economic sanctions against North Korea.

But CrowdStrike says it has been tracking this same group since 2016 – under the moniker Stardust Chollima. Adam Meyers, vice president of intelligence at CrowdStrike, says his firm attributed the hacks against the SWIFT system to the North Korean group.

"Stardust Chollima has been associated with numerous financially motivated attacks meant to generate revenue for the North Korean regime. Attacks have included targeting of the international financial system, regional banks in developing economies, and cryptocurrency exchanges and businesses," Meyers says. "These attacks are expected to continue due to the economic impact on the DPRK due to international sanctions."

No Smash-and-Grab
There's still plenty of overlap among all three of the main North Korean hacking groups, but FireEye researchers say APT 38 stands apart with its specialized custom tools and focus on financial organization operations. APT 38 employs at least 39 toolsets and is known for its deep study of its targets, often remaining inside a target's network for long periods of time before making a move on its data. It's no smash-and-grab operation, said Jacqueline O'Leary, senior threat intelligence analyst at FireEye.

On average, APT 38 spends 155 days in a compromised network. In one case, it sat quietly on a victim's network for two years before making its move for money. "They can balance multiple motivations, they're financially motivated, and they operate like a traditional espionage operation," O'Leary said. "Sometimes they wait two years before attempting transactions" from a bank, for example.

APT 38 spends that time gathering credentials, mapping the network, and scanning systems for information and vulnerabilities.

"Once we saw them leverage a legitimate file program that was already inherent on a compromised host, and they actually used it to transfer and delete the malware," O'Leary said. "And another time we saw them incorporate a hard-coded proxy IP into their malware that was actually specific to the victim's environment."

When APT 38 began to pivot to the SWIFT servers in bank targets, for example, it used a mix of homegrown and legitimate tools: In one case, they used sysmon to gather users and processes that have access to the SWIFT servers, Fraser said. "We've also seen them use both passive and active backdoors ... to tunnel and get access to internal systems," she said.

To transfer stolen funds, APT 38 uses its so-called DYEPACK malware for the fraudulent transactions, which mostly were performed in less conspicuous increments and sent to nations with lax money-laundering laws.

"Then they proceed to burn down the house," Fraser said, including deleting log histories and launching distractions such as ransomware attacks. In one case, it was a phony ransomware attack that wasn't even set up to collect ransom, she said. "That distracted the investigators and then they proceeded to wipe disks," Fraser said.

At one bank, some 10,000 workstations and servers were taken offline by APT 38's destructive cleanup operation to cover its tracks. "Employees walked in to blue screens ... it was just chaos," Fraser said.

APT 38 also has shown some savvy: "In certain cases, we've observed that they initiate an AV scan on a compromised host to see if their own malware would be detected," O'Leary said.

And in keeping with its stealthy approach, APT 38's malware often is difficult to detect. Take its SWIFT-attack malware, which runs in memory so it's not easily detected. "SWIFT malware is never on disk," said Chris DiGiamo, technical director of FireEye's Mandiant team.

FireEye today also published a blog and report on APT 38. 

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