Hackers behind Dark Seoul are back

Pierluigi Paganini November 20, 2015

The hacking group that behind the Dark Seoul Operation that hit entities in South Korea in 2013 may be back with new targets.

According to the experts at Palo Alto Networks, the hacking group behind the attacks that targeted banks, financial institutions, government websites and news agencies in South Korea is still active. The attacks occurred in 2013, the hacking campaign was labeled by security firms as Dark Seoul and Operation Troy. The experts noticed that the variant used in the recent attack doesn’t include the wiper component present in the version that targeted entities in the South Korea. The wiper deletes the Master Boot Record (MBR) making impossible the bootstrap of the machine.

The experts found many similarities between malware used in a recent attack in Europe and that malicious code spread in the attacks against entities in South Korea.

Dark Seoul campaign new attack 2

The attack vector was the email with malicious attachments or containing harmful links, the European organization was recently targeted by a spear-phishing attack.

The malware had been wrapped into legitimate video player software that was hosted by an industrial control systems company,

Security experts Bryan Lee and Josh Grunzweig from Palo Alto explained that threat actors have trojanized a legitimate video player software that was hosted by an industrial control systems company.

“The initial attack was likely a spear-phishing email, which leveraged a trojanized version of a legitimate software installation executable hosted by a company in the industrial control systems sector. The modified executable still installs the legitimate video player software it claims to contain, but also infects the system.” reads the blog post published by Palo Alto Networks. “Based on deep analysis of the Trojan’s behavior, binary code, and previous reports of similar attacks, we have concluded that these samples were the same as the original tools used in the Dark Seoul/Operation Troy attacks” “It is likely the same adversary group is involved, although there is currently insufficient data to confirm this conclusion,” 

In the analysis conducted by McAfee in 2013, the experts identified two parallel operations conducted by initially by two crews that appeared separated, the Whois Hacking Team and the NewRomanic Cyber Army Team. The evidence collected by McAfee lead the firm to concluded it was likely a single group behind both campaigns.

The malware used in the recent attack was controlled through compromised websites in South Korea and Europe. The attackers compromised these websites because they were running out-of-date software.

“The similarities in tactics however, do seem to outweigh the differences, and it is highly likely this is the same group or groups responsible for the original Dark Seoul/Operation Troy attacks, but with a new target and a new campaign,” Palo Alto wrote.

It is quite common to see three actors suspend their activities for a period, especially after the investigation of security firms. Usually, when these dormant threats reappear don’t adopt change completely their hacking arsenal and in many cases they reuse part of the uncovered control infrastructure.

The experts consider insufficient collected data at this time to clearly state why Dark Seoul/Operation Troy would resurface at this time, but they will continue to investigate on it.

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Pierluigi Paganini

(Security Affairs – Dark Seoul, cyber espionage)

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