New ‘MosaicRegressor’ UEFI Bootkit Malware Found Active in the Wild

Cybersecurity scientists have noticed a unusual kind of possibly harmful malware that targets a machine’s booting method to fall persistent malware.

The campaign included the use of a compromised UEFI (or Unified Extensible Firmware Interface) containing a malicious implant, producing it the next acknowledged community situation in which a UEFI rootkit has been utilised in the wild.

According to Kaspersky, the rogue UEFI firmware visuals were modified to incorporate quite a few malicious modules, which were then utilized to drop malware on target devices in a sequence of targeted cyberattacks directed against diplomats and users of an NGO from Africa, Asia, and Europe.

Calling the malware framework “MosaicRegressor,” Kaspersky researchers Mark Lechtik, Igor Kuznetsov, and Yury Parshin said a telemetry investigation disclosed a number of dozen victims in between 2017 and 2019, all of whom had some ties to North Korea.

UEFI is a firmware interface and a alternative for BIOS that increases stability, ensuring that no malware has tampered with the boot method. Simply because UEFI facilitates the loading of the running system by itself, this sort of infections are resistant to OS reinstallation or substitution of the difficult generate.

“UEFI firmware will make for a best system of persistent malware storage,” Kaspersky mentioned. “A advanced attacker can modify the firmware in order to have it deploy destructive code that will be run just after the functioning process is loaded.”

That’s specifically what this menace actor appears to have performed. Whilst the correct an infection vector used to overwrite the original firmware continues to be not known at this phase, a leaked handbook indicates the malware may have been deployed via physical accessibility to the victim’s device.

UEFI Bootkit Malware

The new UEFI malware is a custom version of the Hacking Team’s VectorEDK bootkit, which was leaked in 2015 and has because been offered on-line. It really is utilized to plant a next payload, known as the MosaicRegressor — “a multi-phase and modular framework aimed at espionage and knowledge gathering” that is made up of extra downloaders to fetch and execute secondary parts.

The downloaders, in flip, contact the command-and-handle (C2) server to seize upcoming-phase DLLs in buy to execute precise commands, the effects of which are exported back to the C2 server or forwarded to a “comments” mail handle from the place the attackers can obtain the amassed info.

The payloads are transferred in a wide variety of means, which include by way of e-mail messages from mailboxes (“mail.ru”) difficult-coded in the malware’s binary.

In some cases, nonetheless, the malware was shipped to some of the victims by way of spear-phishing e-mails with embedded decoy paperwork (“0612.doc”) composed in Russian that purported to examine situations linked to North Korea.

With regards to the identity of the threat actor guiding MosaicRegressor, Kaspersky explained it uncovered a number of code-level hints that point out they had been composed in Chinese or Korean and mentioned the use of Royal Highway (8.t) RTF weaponizer, which has been tied to various Chinese threat groups in the previous.

UEFI Bootkit Malware

And lastly, Kaspersky uncovered a C2 tackle in 1 of MosaicRegressor’s variants that have been observed in relationship with Chinese hacker groups broadly acknowledged as Winnti (aka APT41).

“The assaults […] exhibit the duration an actor can go in order to gain the best amount of persistence on a victim equipment,” Kaspersky concluded.

“It is remarkably unheard of to see compromised UEFI firmware in the wild, ordinarily because of to the low visibility into assaults on firmware, the state-of-the-art actions expected to deploy it on a target’s SPI flash chip, and the large stakes of burning sensitive toolset or assets when undertaking so.”

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