A newly discovered attack tool used by multiple groups of Chinese-speaking attackers has infected more than 1,000 machines in South Korea -- mainly universities and other academic institutions.

The so-called PinkStats malware family has been in use over the past four years, targeting various nation-states and organizations around the globe, according to Aviv Raff, CTO at Seculert, which studied the malware and posted its findings today.

"This is the first proof that there are Chinese-speaking attackers targeting [South Korea] entities," says Raff, who stopped short at confirming the attackers were from China. Even so, he says it's likely that they are Chinese: "These type of custom-made tools are usually created by the people speaking the language used in the tool, [such as where] Mahdi used Farsi strings," he says.

There's no evidence, either, to confirm that PinkStats was also used in the attacks earlier this year on South Korean banks, media networks, and an ISP that wiped hard drives and attached drives of infected machines. They also crippled targeted organizations for hours, and the machines weren't able to reboot. There was speculation of a North Korea or China connection to the attacks.

[Researchers confirm data-destroying malware that hit South Korean media and banks doesn't completely erase data. See Data Can Be Recovered From South Korea Data-Wiping Attacks. ]

PinkStats is a Trojan downloader that can install additional malware components. It camouflages itself by posing as a Web statistics or counter service in its communications to the command-and-control server and in the attacker's administrative panel login window.

In the South Korean attack, PinkStats also downloaded a typical Chinese hacking tool called zxarps that acts as a worm to spread in the victim's local network, via address resolution protocol (ARP) poisoning. The malicious iFrame it injects includes an ActiveX file digitally signed by Thwate. Seculert says the signature was valid as of May 8 and uses "Microsoft Corporation" as the product name and "Liaocheng YuanEr Technology CO., ltd.," as the publisher name -- a phony South Korean company.

PinkStats also installs a DDoS malware tool that goes by "Win8.exe" and poses as South Korean antivirus company AhnLab's V3 Light Framework software. "Up until now, the adversary did not seem to send any specific instructions to the installed DDoS malware. However, with the recent incidents of DDoS attacks against South Korean infrastructure, it is reasonable to assume that this state could change anytime soon," Seculert said in its blog post.

Seculert's Raff says the attackers were trying to amass as much computing power as possible from the South Korean universities. They deployed an additional worm tool that spreads the PinkStats malware within the local university network," he says, probably in order to use the machines for DDoS attacks.

Raff says his firm discovered the PinkStats malware while analyzing one of its customer's logs. That analysis led to Seculert finding evidence of the South Korean attacks. What makes PinkStats unique is that it's a downloader posing as a legitimate Web statistics service. "So even if someone will try to investigate the URL of the malware communication and [get] to the login page, he will see a page saying that is a login for 'statistics administration,'" he says.

Other attacks using PinkStats have downloaded information-stealing Trojans as well, he says.

"It really depends on the group using this tool, and the intent of their current operation and phase," Raff says.

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