U.S. Defense, Critical Infrastructure Companies Targeted in New Threat Campaign

A cyberthreat group using malware tied to the Sony Pictures hack of late 2014 is attacking nuclear, defense, energy, and financial companies in what appears to be a campaign to gather information for future exploitation.

In October and November alone, the malware has appeared on systems belonging to at least 87 organizations, most of them in the US, McAfee said in a report this week.

The actors behind "Operation Sharpshooter," as McAfee is calling the campaign, are distributing the malware via malicious Word documents purporting to be job recruitment-related. All of the malicious documents have English-language descriptions for jobs at unknown companies and have been sent from a US-based IP address and via the Dropbox service, the security vendor said.

"From what we were able to gather, the malicious documents were sent to target persons at organizations involved with key programs the actor was looking to gather data on," says Ryan Sherstobitoff, senior researcher at McAfee.

McAfee has not been able to determine with certainty how the attackers are delivering the rogue Word document to target individuals, Sherstobitoff says. "But we suspect it was delivered via spear-phishing with a link to the site that hosted the maldoc," he says.

The malicious document contains a weaponized macro that uses embedded shellcode to inject the Sharpshooter downloader into Word's memory, McAfee said.

Sharpshooter initiates a four-step process to download "Rising Sun," a second-stage implant that also runs in memory and collects intelligence about the machine. The second-stage binary is downloaded to the infected endpoint's startup folder to ensure persistence on the system. Sharpshooter also downloads a second — benign — Word document from the control server, most likely as a decoy to hide the malware, McAfee said.

Rising Sun's capabilities include collecting network adapter information, computer name, user name, IP address information, OS information, drive and process information, and other native system data. The malware is designed to then encrypt the harvested data using the RC4 algorithm and encoding the encrypted data with Base64 before sending it off to the control server. The control servers being used in the campaign are located in the US, Singapore, and France.

The Rising Sun implant supports 14 different backdoor capabilities in total, including the abilities to terminate processes, clear process memory and write files to disk McAfee said in its report.

Shared Code and TTPs
What makes Rising Sun noteworthy is that it uses source code from Trojan Duuzer, a backdoor that North Korea's infamous Lazarus Group used in its attack on Sony in late 2014 and early 2015.

There are several other similarities as well, McAfee said. The documents that are being used to distribute Rising Sun contain metadata indicating they were created using a Korean-language version of Word. Both malware tools use the same techniques for constructing and decoding library names and API names, and both have a nearly identical set of capabilities. Other tactics, techniques, and procedures used in the Sharpshooter campaign are also similar to those employed by the Lazarus Group in its Sony campaign, McAfee said.

However, the connections between the two campaigns are so obvious that it is quite possible the threat actors behind Operation Sharpshooter are planting false flags to make attribution more difficult, McAfee noted.

Rising Sun's communication mechanism and encoding schemes are two areas where it differs from Duuzer. "[Rising Sun] is more sophisticated in terms of the implementation of the command code structure as well as the decoding scheme," Sherstobitoff says. The encryption method it uses is more advanced than Duuzer, too. "There is clear indication this implant is not just an upgraded version of Duuzer," he says.

But for all the sophistication of the malware itself, Operation Sharpshooter is yet another reminder of the threat companies face from employees opening attachments or clicking on links that they should have avoided.

"Phishing is one of the oldest techniques in the book," said Leigh-Anne Galloway, cybersecurity resilience lead at Positive Technologies. In most cases, phishing emails lack sophistication or are moved automatically to the spam folder. But with sophisticated campaigns such as Sharpshooter, even large companies are vulnerable, she said.

"Phishing emails play on a person's emotions, providing a level of incentive for opening a file or clicking on a link," Galloway said. The risk associated with phishing can be reduced through proper user awareness training, she said.

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