Security Experts:

New KillDisk Variant Spotted in Latin America

A new variant of the disk-wiper malware known as KillDisk has been spotted by Trend Micro researchers in attacks aimed at financial organizations in Latin America.

The security firm is in the process of examining the new variant and the attacks, but an initial analysis showed that the Trojan appears to be delivered by a different piece of malware or it may be part of a bigger attack.

Early versions of KillDisk were designed to wipe hard drives in an effort to make systems inoperable. The malware was used by the Russia-linked threat actor BlackEnergy in the 2015 attack aimed at Ukraine’s energy sector.

Roughly one year after the Ukraine attack, researchers reported that its developers had turned KillDisk into file-encrypting ransomware. However, the samples analyzed at the time used the same encryption key for all instances, making it possible for victims to recover files.

Experts later reported seeing a KillDisk ransomware designed to target Linux machines, but the malware did not save encryption keys anywhere, making it impossible to recover files.

Some links have also been found between KillDisk and the NotPetya malware, which initially appeared to be a piece of ransomware but later turned out to be a disk wiper. NotPetya hit machines in more than 65 countries and major companies reported losing hundreds of millions of dollars as a result of the attack.

The latest variant, which Trend Micro tracks as TROJ_KILLDISK.IUB, goes back to its roots and focuses on deleting files and wiping the disk. The malware, designed to target Windows systems, goes through all drives in order to delete files, except for system files and folders.

It then proceeds to wipe the disk, which includes reading the master boot record (MBR) and overwriting the extended boot record (EBR). The file removal and disk wiping procedures involve overwriting files and disk sectors in order to make recovery more difficult.

Once files and partitions have been deleted and overwritten, the malware attempts to terminate several processes in an effort to reboot the infected machine. By targeting processes associated with the client/server runtime subsystem (csrss.exe), Windows start-up (wininit.exe), Windows logon (winlogon.exe), and the Local Security Authority Subsystem Service (lsass.exe), the malware can force a blue screen of death (BSOD), a logout, or a restart.

Trend Micro has promised to share more information on the new KillDisk variant as its investigation continues.

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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.