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ESET researchers have discovered an operation, with a possible link to the infamous Lazarus group, that used unconventional spearphishing and custom, multistage malware against aerospace and military companies.

BRATISLAVA – ESET researchers have discovered highly targeted cyberattacks that are notable for using LinkedIn-based spearphishing, employing effective tricks to stay under the radar and apparently having financial gain, in addition to espionage, as a goal.  The attacks, which ESET researchers dubbed Operation In(ter)ception based on a related malware sample named “Inception.dll,” took place from September to December 2019.

The attacks that ESET researchers investigated started with a LinkedIn message. “The message was a quite believable job offer, seemingly from a well-known company in a relevant sector. Of course, the LinkedIn profile was fake, and the files sent within the communication were malicious,” comments Dominik Breitenbacher, the ESET malware researcher who analyzed the malware and led the investigation.

The files were sent directly via LinkedIn messaging, or via email containing a OneDrive link. For the latter option, the attackers created email accounts corresponding with their fake LinkedIn personas.

Once the recipient opened the file, a seemingly innocent PDF document with salary information related to the fake job offer was displayed. Meanwhile, malware was silently deployed on the victim’s computer. In this way, the attackers established an initial foothold and reached a solid persistence on the system.

Next, the attackers performed a series of steps that ESET researchers describe in their white paper “Operation In(ter)ception: Targeted attacks against European aerospace and military companies.” Among the tools the attackers utilized was custom multistage malware that often came disguised as legitimate software, and modified versions of open-source tools. In addition, they leveraged so-called “living off the land” tactics: abusing preinstalled Windows utilities to perform various malicious operations.

“The attacks we investigated showed all the signs of espionage, with several hints suggesting a possible link to the infamous Lazarus group. However, neither the malware analysis nor the investigation allowed us to gain insight into what files the attackers were aiming for,” comments Breitenbacher.

Besides espionage, ESET researchers found evidence that the attackers attempted to use the compromised accounts to extract money from other companies.

Among the victim’s emails, the attackers found communication between the victim and a customer regarding an unresolved invoice. They followed up the conversation and urged the customer to pay the invoice – of course, to a bank account of their own. Fortunately, the victim company’s customer became suspicious and reached out to the victim for assistance, thwarting the attackers’ attempt to conduct a so-called business email compromise attack.“

This attempt to monetize the access to the victim’s network should serve as yet another reason for both establishing strong defenses against intrusions and providing cybersecurity training for employees. Such education could help employees recognize even lesser-known social engineering techniques, like the ones used in Operation In(ter)ception,” concludes Breitenbacher.

For more technical details about Operation In(ter)ception, read the full blogpost and white paper “Operation In(ter)ception: Targeted attacks against European aerospace and military companies” on WeLiveSecurity. Make sure to follow ESET Research on Twitter for the latest news from ESET Research.