Windows and Linux in Crosshairs of Botnet

A botnet referred to as “Sysrv-K” is targeting computers that run on both Windows and Linux operating systems. According to researchers with Microsoft, the botnet uses bugs within a Spring Framework and WordPress plugins. The Spring Framework with unaddressed susceptibilities and vulnerable plugins for WordPress is at risk of exploitation by cyber miscreants. In particular, the criminals responsible for the Sysrv botnet that targets Windows and Linux operating systems seek to infect target systems with lware that performs cryptocurrency mining.

What is the Botnet Variant Sysrv-K all About?

The botnet variant was developed by hackers who created a full bot army to search for weaknesses within WordPress plugins. The botnet army also seeks out RCE flaws within Spring Cloud Gateways. RCE is short for remote code execution. The weaknesses in question have been addressed through security patches. However, if Sysrv-K begins operating on a device, it will implement its miner for cryptocurrency, essentially stealing the target machine’s computing power to mine cryptocurrency that is sold for profit. Part of what also makes Sysrv-K a unique botnet is its ability to obtain control over web servers.  

What is the Spring Cloud Gateway’s Role?

The Spring Cloud is significant because it serves as an open-source library that facilitates the development of applications for the cloud. The Gateway also serves as a helpful library for creating API Gateways for both Java and Spring. However, when the Spring Cloud Gateway code injection vulnerability is used, cybercriminals are empowered to conduct remote code execution to target hosts that lack the necessary patching. The flaw in question pertains to products made by both Oracle and VMware.

Why is Sysrv-K Such a Major Issue in Cybersecurity?

Microsoft’s security intelligence crew has gone out of its way to warn the general computing public that Sysrv-K is a dangerous botnet that can obtain control over the web servers through a scan of the internet for potential weaknesses that set the stage for an installation and infection. Arbitrary file downloads, RCE, path traversal for the disclosure of remote files, and additional vulnerabilities can be easily exploited. The malware is transmitted across networks by scanning the web for vulnerabilities and installing the cryptocurrency mentioned above miner to mine monero.  

The latest version of Sysrv-K is advanced because it searches for WordPress config files and backups to steal login credentials and ultimately uses the webserver. Sysvr-K has updated its communication capabilities along with its use of a Telegram bot. However, the new Sysrv-K also performs scans for hostnames, IPs, and SSH keys, as occurred with previous incarnations. The botnet then tries to link with other systems through the network through the SSH to transmit copies of itself. The result is a threat to the entire network as it has the potential to be consumed by the overarching Sysrv-K botnet.

What can Organizations do to Guard Against the Botnet?

Microsoft recommends organizations implement fully secure operating systems that are internet-facing, implement the latest digital security updates and safeguard credentials as best possible. The company’s representatives also noted that Microsoft Defender identifies Sysrv-K and older versions of the botnet and related payloads and other signature characteristics.