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North Korean Hackers Prep Attacks Against Cryptocurrency Exchanges: Report

Researchers Say a North Korea-Linked Hacking Campaign is Ready to Go Against South Korean Cryptocurrency Exchanges

North Korean hackers, loosely categorized as the Lazarus Group, have continued their attacks against South Korean interests, with particular emphasis on cryptocurrency exchanges. 

Recorded Future has published details of a campaign it discovered in late 2017, which does not yet appear to be active. This may be in recognition of, or because of, the current discussions between North and South over North Korea's potential involvement in South Korea's Winter Olympics being held in Pyeongchang in February -- or it could simply be that the campaign development has not yet been put in action.

Recorded Future said they discovered a spear-phishing campaign that uses the CVE-2017-8291 Ghostscript vulnerability triggered from within a Hangul Word Processor (popular in South Korea) document.

For now, the bilateral discussions between North and South seem to be fruitful. It is reported that North Korea will send a 140-member orchestra to the Games, and there are ongoing discussions over the two countries fielding a joint women's hockey team. Nevertheless, Recorded Future researcher Priscilla Moriuchi told SecurityWeek that the campaign is in place and could be easily invoked.

Earlier this month, McAfee described a separate attack against North Korean defectors from a group -- almost certainly North Korean -- that does not appear to be related to any known cybercrime group.

Recorded Future notes that the techniques used in that attack "are unusual for the Lazarus Group. These include leveraging PowerShell, HTA, JavaScript, and Python, none of which are common in Lazarus operations over the last eight years." This new campaign, however, "showcases a clear use of Lazarus TTPs to target cryptocurrency exchanges and social institutions in South Korea."

The Lazarus targets are users of the Coinlink cryptocurrency exchange, other exchanges, and a group known as 'Friends of MOFA (Ministry of Foreign Affairs)'. 

The cryptocurrency target is typical Lazarus. "Beginning in 2016," notes Recorded Future, "researchers discovered a shift in North Korean operations toward attacks against financial institutions designed to steal money and generate funds for the Kim regime." Lazarus is believed to be behind the 2016 attacks on the SWIFT global banking network, including the theft of $81 million from the Bangladesh central bank in February 2016.

In December 2017, the South Korean Youbit cryptocurrency exchange went bankrupt following its second hack of the year. In the first attack it lost 4000 bitcoin or around 40% of its reserves (around $5 million at the time), and a further 17% of its assets in the December breach. Some reports suggest that the attacks were undertaken by BlueNoroff, a sub-group of Lazarus.

South Korean exchanges have been strengthening their network defenses, while the government has been considering regulations to tighten control over cryptocurrencies. One mooted option has been the shutdown of all virtual cryptocurrency exchanges, although a statement from the Office for Government Policy Coordination on Monday downplayed a comment from Justice Minister Park Sang-ki last week. The Justice Minister's statement suggested the government is already working on legislation to ban virtual exchanges in the country. The current view is that a ban is not imminent, although stricter regulation is likely.

Whatever happens, hacking South Korean cryptocurrency exchanges will become more difficult in the future. "The majority of North Korean cryptocurrency operations have targeted South Korean users and exchanges, but we expect this trend to change in 2018. We assess that as South Korea responds to these attempted thefts by increasing security, they will become harder targets, forcing North Korean actors to look to exchanges and users in other countries as well."

Noticeably, Recorded Future warns that although this campaign and toolset are specific to the Hangul Word Processor, the actul vulnerability it exploits is not. "This vulnerability is for the Ghostscript suite and affects a wide range of products, and while this particular version is triggered from within an embedded PostScript in an HWP document, it could easily be adapted to other software."

"The main targets and victims of North Korean cryptocurrency operations in 2017 were South Korean," Moriuchi told SecurityWeek. "As a result of that targeting, the South Korean regulators are attempting to impose stricter financial controls on exchanges, and the exchanges are also implementing stricter security measures both for their users and within their networks. We believe that these factors will lead North Korea -- which is clearly invested in cryptocurrency operations -- to pursue other targets in other countries because the South Korean targets are becoming harder to get at." 

This campaign is delivered by spear-phishing emails. Four separate lures have been identified: one aimed at users of Coinlink; two that appear to be resumes stolen from two genuine South Korean computer scientists who work at cryptocurrency exchanges; and one lifted from a blog run by the Friends of MOFA. All of the lure documents were created between mid-October and late November.

"This campaign relies on multiple payloads fashioned out of the Destover infostealer code to collect information about the victim system and exfiltrate files," reports Recorded Future. Destover further implicates Lazarus in the campaign. It was used in the Sony Pictures Entertainment attack in 2014, the Polish banking attacks in January 2017, and in the first WannaCry victim discovered by Symantec.

Recorded Future does not believe that any improving relations between North and South Korea will stop Lazarus targeting South Korea. The campaign could kick off at any time. But the suggestion is that as attacking South Korean exchanges becomes more difficult and less fruitful, the same attack could relatively easily be re-engineered for different exchanges in different countries.

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Kevin Townsend is a Senior Contributor at SecurityWeek. He has been writing about high tech issues since before the birth of Microsoft. For the last 15 years he has specialized in information security; and has had many thousands of articles published in dozens of different magazines – from The Times and the Financial Times to current and long-gone computer magazines.