Security Experts:

North Korea-Linked Hackers Target U.S. Defense Contractors

The North Korea-linked cyber espionage group known as Lazarus is believed to be behind attacks targeting individuals involved with United States defense contractors, Palo Alto Networks reported on Monday.

The threat actor, which has been active since at least 2009, is said to be responsible for several high-profile attacks, including the 2014 attack targeting Sony Pictures. Links have also been found to the recent WannaCry ransomware attacks.

The Lazarus group, tracked by the U.S. government as Hidden Cobra and known by security firms for its Operation Blockbuster, Dark Seoul and Operation Troy campaigns, continues to be active. Recent attacks observed by Palo Alto Networks against U.S. defense contractors appear to have been launched either by this group directly or in cooperation with other cyberspies.

According to researchers, the hackers have sent out spear phishing emails containing weaponized Microsoft Office documents written in English that use macros to deliver a piece of malware.

Specifically, Palo Alto has seen decoy documents describing job openings at some U.S. defense contractors. The text in these documents appears to be an exact copy, including typos, of job descriptions available on the legitimate company’s website.

There are several links between these attacks and other recent campaigns, including very similar macros, decoy document details, command and control (C&C) servers, and payloads.

“This reuse of macro source code, XOR keys used within the macro to decode implant payloads, and the functional overlap in the payloads the macros write to disk demonstrates the continued use of this tool set by this threat group. The use of an automated tool to build the weaponized documents would explain the common but not consistent reuse of metadata, payloads, and XOR keys within the documents,” researchers explained.

Palo Alto Networks pointed out that the tools and tactics used by the group have changed only little compared to previous campaigns, despite the numerous reports describing its activities. This has led experts to believe that the Lazarus group will continue to launch targeted attacks.

While the gang has been tied to several espionage and destruction campaigns, many of its recent attacks appear to have focused on financial institutions, including Bangladesh’s central bank and banks in Poland.

Related: Russian Words Used as Decoy in Lazarus-Linked Bank Attacks

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Eduard Kovacs is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.