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Linux Trojan Takes Screenshots Every 30 Seconds

Russian antivirus company Doctor Web reported finding a new Linux Trojan that appears to be designed to help cybercriminals spy on users.

Detected by Dr. Web products as Linux.Ekoms.1, the malware takes screenshots every 30 seconds and saves them to a temporary folder in the JPEG format using the extension .sst. If the screenshot cannot be saved as a JPEG, Ekoms attempts to save it in the BMP image format.

An analysis of the Trojan revealed that its developers are also working on a feature designed to record audio and save the recording in WAV format in a file with the .aat extension in the same temporary folder. While the sound recording feature exists, it’s not active in the Ekoms variant analyzed by Dr. Web.

The malware is designed to periodically search its temporary folder for files with certain names and extensions. It looks for .aat and .sst files, which are supposed to store screenshots and audio recordings, and also for .ddt and .kkt files, which suggests the malware authors might be targeting other type of content as well.

The files that match the search criteria are uploaded to a remote server whose address is hardcoded in the malware. All data sent by Linux.Ekoms.1 to the server is encrypted.

Attackers can use the command and control (C&C) server to send various commands to the threat, including to download other files, and enable or disable specified services. There are some instructions that have not been implemented, which also suggests the Trojan is still under development.

Linux systems are increasingly targeted by various types of malware, and many of the threats are designed to help malicious actors launch distributed denial-of-service (DDoS) attacks.

Linux ransomware has also started making rounds over the past period. The file-encrypting ransomware Linux.Encoder targets web servers, websites, backups and source code stored on infected machines.

Linux.Encoder infected thousands of devices, but researchers found a flaw that can be leveraged to recover encrypted files without paying the ransom. Linux.Encoder is reportedly based on Hidden Tear, an open source ransomware whose author intentionally weakened encryption to prevent abuse.

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Eduard Kovacs (@EduardKovacs) 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.