Security Experts:

North Korean Hackers Exploit HWP Docs in Recent Cyber Heists

A series of malicious Hangul Word Processor (HWP) documents used in recent attacks on cryptocurrency exchanges have been attributed to the North Korea-linked Lazarus group, AlienVault reports.

The attacks appear to include the recent assault on Bithumb, the largest virtual currency exchange in South Korea, with more than 1 million customers. As part of the incident, hackers managed to steal over $30 million worth of cryptocurrencies.

Lazarus, or BlueNoroff, is a state-sponsored hacking group believed to have launched the $81 million cyber heist from the Bangladesh Bank in 2016 and considered the most serious threat against banks. Earlier this year, the group was observed hitting an online casino in Central America and switching interest to crypto-currency.

Earlier this month, AlienVault revealed that Lazarus has been leveraging a new ActiveX vulnerability in attacks on South Korean targets. Now, the security firm says that the hackers have also been using a series of malicious documents to target members of a recent G20 Financial Meeting.

AlienVault's security researchers analyzed three similar malicious documents that have been already associated with Lazarus. One of these mentions the G20 International Financial Architecture Working Group meeting, seeking coordination of the economic policies between the wealthiest countries.

The HWP files include malicious code that fetches next stage malware (either a 32 or 64 bit version of Manuscrypt, which has been already detailed by other security researchers), a threat communicated by impersonating South Korean forum software. Decoy documents of resumes were also included.

A series of reports within South Korea have already suggested that malicious HWP files were used earlier in May and June to set up the Bithumb heist, and that these documents appear linked to previous attacks by Lazarus.

The investigation of a South Korean security company into the thefts also revealed that fake resumes strikingly similar to those delivering the Lazarus-linked Manuscrypt were sent to cryptocurrency organizations.

“Whilst we can’t be certain this malware is responsible for the thefts from Bithumb, it seems a likely suspect,” AlienVault notes.

Related malicious HWP documents from Lazarus have been reportedly targeting crypto-currency users in South Korea earlier this month.

Furthermore, the researchers noticed cryptocurrency phishing domains registered to the same phone number as a domain (itaddnet[.]com) and delivering some of the malware. This would suggest the attackers are also phishing for credentials, in addition to delivering malware.

“It is unusual to see Lazarus registering domains - normally they prefer to compromise legitimate websites. So this would be an unusual attack if it is indeed run by members of Lazarus,” AlienVault says.

Apparently, it would be entirely possible for Lazarus to have hacked Bithumb earlier this month, considering that the group raided the exchange last year as well, which likely provided them with the necessary knowledge to do it again. Over the past year, the group targeted other crypto-currency exchanges as well.

“It’s clear that the thefts from Lazarus won’t stop anytime soon given the gains available - the (partially successful) attempt to steal $1 billion dollars from the Bank of Bangladesh represents 3% of North Korea’s reported GDP. Thefts from South Korean organizations have the double impact of weakening their closest competitor,” AlienVault said.

Related: North Korean Hackers Abuse ActiveX in Recent Attacks

Related: North Korea-Linked Group Stops Targeting U.S.

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